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Post Info TOPIC: Exhaust Header Glowing Red


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Hi all Been for two runs out on the bike today to get some fresh fuel through the bike and five it a decent run out to see if it helps with its starting problems. I have just got back and the front pipe was glowing red hot in the dark, is this normal or due to the mixture been out?? Or possible air leak??

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I can't advise on the TTR glowing pipe but way back in the early 70s my Tiger Cub pipe glowed red due to ignition timing being way out. furious

I would guess it's your carburettor settings that need attention since there's not a lot to adjust in the ignition department. confuse

I'm sure Jarra wil have a response - so hang on in there. biggrin

Martyn



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My Raid does this when it's warming up on choke but is fine when running off choke. However my 05 TTR also does it on choke but I did notice last weekend after a run up the road in the dark that the pipe was glowing.

With it doing it on choke is a bit odd as a richer mixture should make it run cooler. But my Raid runs ok and now has 53,000 miles on it with just the one re-bore.

In my last job working on CHP units that ran on natural gas, each exhaust port had a thermocouple fitted to it and was monitored by an on board computer. if the temp on one cylinder dropped below a set temp it would trip the machine on a mis-fire.

However a high exhaust temp' on one cylinder would indicate a tight or burned valve which was allowing the burning gases in to the manifold.

But you have checked the valves.

Sorry that this may not help much!! But to Summerize, mine does it and it's been ok for many years!

 

Peter



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I've got a smooth spot in a finger when I wanted to see how hot it gets recently, they get really hot !!

that's the extent of my scientific method  no

 



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The header pipe should not glow red unless you own a YZ450F & then it is normal smile

Peter is on the right track as with all.

I think that either the timing has jumped a tooth or two... (not much response,hard to start,overheating,cam chain noise ect.)

The valves need re-shimming (would be a making a tapping sound)

Air leak (test by spraying wd40 or similar around carby & boot)

Faulty spark plug (can happen..easy fix)

Clogged fins (does'nt explain not starting properly)

Clogged carby (explains overheating & not starting)

Clogged intake

Dirty air filter

................

Of course there are more possible causes but they are the main ones i can think of for now.

...................

Jarrah.

 



-- Edited by barra8 on Thursday 6th of December 2012 12:59:10 AM

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The only time that i have seen the pipe glowing red was on my mates bike
and the cause of it was the carburettor rubber that connects to the head
was drawing air and even though the bike would run and drive, it wasn't
running as it should and the pipe would start to glow after it had been running
a while. The pipes do get hot but not to the extent that the would be glowing
i would have thought, but as i said above that's what was causing it in our case
anyway. Hope this is of some help.

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Ok I have got two threads going here possibly on the same problem, I have had the carb stripped and cleaned, hopefully all back together ok! The bike does seem to be running quite lean judging by the spark plug so I have screwed the mixture screw at the front of the carb approx three turns out. There is no snorkel in the airbox so that maybe causing the week mixture. Another little thing is when I turn off the engine when hot it gives a little back fire noise through the exhaust??

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domski1 wrote:

Ok I have got two threads going here possibly on the same problem, I have had the carb stripped and cleaned, hopefully all back together ok! The bike does seem to be running quite lean judging by the spark plug so I have screwed the mixture screw at the front of the carb approx three turns out. There is no snorkel in the airbox so that maybe causing the week mixture. Another little thing is when I turn off the engine when hot it gives a little back fire noise through the exhaust??


 If the compression is down 50psi then that is your ''cold starting'' problem. The compression needs to be tested cold/hot/no oil though to know for sure if this is causing the problem. If the rings need replacing i would suggest the valves need re-shimming & timing chain replaced. The snorkel at the top could be causing the ''lean'' carby & pop when turned off.

................

Jarrah.



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Ok, I stripped the carb down again and checked the jet sizes, the main jet was a 130 so I bought a 137 from Brian and that seems to have helped with the from pipe glowing so I am also assuming its running a little less lean. Not checked plug yet though. There is a slight glow at the very start of the front pipe in the dark but a lot less than there was. It still isn't great to start, if you give it three or for twists of the throttle before starting that seems to help!



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LRJ


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Exhaust Header Glowing Red
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I happened to use the TTR to commute to work early one morning (about 5 am--dark) last week and I noticed that the header pipe got a pretty bright red while warming up with the choke on.  After easing off the choke and riding the bike with normal throttle, I leaned over and saw that the exhaust header continued to glow.   I saw that it was glowing as I rode home late that evening.   If I stopped the bike and idled, the pipe would cool and the glowing disappeared within a minute or so.  Everyone to whom I subsequently spoke agreed that the exhaust header should not be glowing red. disbelief 

My motorbike mechanic had just checked the spark plug while checking valve clearance  a week earlier and hadn't seen the normal evidence of running too lean.  I brought the bike back to him today, and he cleaned out the carb, checked that the jets were stock (#50 and #137 for yr 2000 North American models) and clean, adjusted the needle to the richest setting, and adjusted the mixture screw to 2.5 turns out.  It now still glows red after I have been riding it, pushing it a bit.  It doesn't glow while idling, and if I stop the bike, the glowing disappears.  The bike runs really well (and ran well before the enrichment).  I have the stock exhaust system and an unmodified air box--the engine is all stock. Granted, it is pretty dark at night where I live (in the woods, no street lights), and the glowing is not that noticeable in well-lit areas.  

confuseDoes anyone have any other suggestions.  Could this glowing possibly be normal and most people don't notice it, because they don't ride their bikes at night, or its not that dark where they live?  After all, it does take some awkward movement to lean over and check the header while riding.  Any thoughts or suggestions would be well appreciated.

Thanks,

Larry



-- Edited by LRJ on Sunday 17th of February 2013 06:20:00 AM

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If the valves are in spec then it suggests that your main jet is too small. I'd try going up in sizes until it runs bad,then go down a size. Australian standard size is #147 main jet so maybe closer to this would be better.



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Hi Larry, i ride my bike a bit in the dark and have never noticed this "glowing header pipe" that yours has, i aggree with TT-R250M and would try a larger jet

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I had a problem with my header glowing, poor starting and idling, it turned out that I had the incorrect main jet fitted and the idle mixture was slightly lean, I think that most ttr's will glow very slightly when they are on the choke in the dark though.

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Can a photo be taken of the pipe glowing red hot? confuse

I guess a flash would mask the glow so it would have to be a long exposure, maybe.

sxnanggwpf9.jpg

Yuraku



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The choke is an enrichener so i don't see why it would glow red from using it at any time. If your valves are out of spec it will make you run lean & backfire etc although you said these have been checked so it's definitely main jet.



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"The choke is an enricher"...and yet, paradoxically, it seems to be a common experience of many people with whom I have spoken that the header glows with the choke engaged on a number of different types of bikes.

You are probably correct, TT-R250M, that a larger main jet would remedy the situation, but it is frustrating that the jet that I have is stock and so is the rest of the engine system. (At least I believe that it is.) It is true that on bikes exported to areas other than North America the main jet is larger than what I have, but those bikes also have a different exhaust system than the North American bikes. A quick glance at the mufflers/silencers will tell one that the two are not the same.

When I purchased the bike it had a Big Gun exhaust system, a Mikuni pumper carb, and a desnorkeled air box. Because it wasn't running well at low elevations with that set up (coughing, backfires), and because it was too loud, I replaced the exhaust, carb, and air box with stock parts. With the stock parts, all seems well (runs well, no backfire, starts right up), but the header glows in the dark.

I am sure there is a missing piece of information causing this conundrum, but a larger main jet may have to suffice. I just don't want my mileage to drop any lower. I've only been getting around 50 mpg (US), and I would have hoped for better. Again, it doesn't seem like a symptom of running too lean.

Larry

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LRJ wrote:

I've only been getting around 50 mpg (US), and I would have hoped for better. Again, it doesn't seem like a symptom of running too lean.

Larry


 Hey Larry

50 mpg seems like it's right on the money, if that's US gallons, that's equel to 3.78 ltr (rounded off) so I get 20 klm per litre

so that = 75.6 klm = 46.9 mpgf

So that's pretty close depending on hjow heavy handed you are on the gas

smile

 



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LRJ wrote:

"The choke is an enricher"...and yet, paradoxically, it seems to be a common experience of many people with whom I have spoken that the header glows with the choke engaged on a number of different types of bikes.

You are probably correct, TT-R250M, that a larger main jet would remedy the situation, but it is frustrating that the jet that I have is stock and so is the rest of the engine system. (At least I believe that it is.) It is true that on bikes exported to areas other than North America the main jet is larger than what I have, but those bikes also have a different exhaust system than the North American bikes. A quick glance at the mufflers/silencers will tell one that the two are not the same.

When I purchased the bike it had a Big Gun exhaust system, a Mikuni pumper carb, and a desnorkeled air box. Because it wasn't running well at low elevations with that set up (coughing, backfires), and because it was too loud, I replaced the exhaust, carb, and air box with stock parts. With the stock parts, all seems well (runs well, no backfire, starts right up), but the header glows in the dark.

I am sure there is a missing piece of information causing this conundrum, but a larger main jet may have to suffice. I just don't want my mileage to drop any lower. I've only been getting around 50 mpg (US), and I would have hoped for better. Again, it doesn't seem like a symptom of running too lean.

Larry


 Maybe someone has done head porting to it. If so you would need a larger main jet.

The stock #137 main seems really lean to me but i guess there are many factors to consider. Elevation,climate,fuel quality,manufacturer tolerances for the particular bike,mods etc the list goes on & on.

Funny thing is that you seem to be getting similar mpg as us Australian's with a standard #147 main jet. Lucky you smile



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I sincerely appreciate everyone's support in helping me to get to the bottom of this issue.

In response to Yuraku, the header pipe is the original one, and it is stainless.

BM Steve, that mileage comparison is good information to know. I was comparing my TTR mileage with the mileage I get with my XT225 (low to mid 80's mpg). I am not very heavy handed with the throttle, but I have full knobbies, front and back, and (from experience) they can bring down mileage a fair bit.

Most others agree with you, TT-R250M, that it isn't good to have the engine that hot. I am afraid that I don't know what "head porting" is, but it is possible that other modifications have been made to the bike of which I am unaware. A cousin raised the possibility that the timing chain was modified when the carb and exhaust were changed. Would that have made sense? That sounds like an expensive thing to have to have checked....I am no mechanic. (I can only marvel at the rebuilding efforts that Brian and others have posted.) If the timing chain has been altered, do the valves have to be adjusted differently? Is it safe to just use a larger main jet and leave the chain alone?

Brian, I also wish that I understood the paradoxes involved with mixture richness. I checked everything again last night after switching back to an older, original, air filter on the off chance that the newer one was more porous to air. Header starting glowing after a minute or so with the choke on, stopped doing so when I shut the choke off and just let it idle, then started glowing again as I rode around a little. It definitely glowed brighter at higher revs than at lower revs.

I always put the highest octane fuel (91, I think it is) that we have available in California in the bike, but our fuel has ethanol and other additives that probably aren't good for the engine. I would be interested to hear what the observations and experience of other NA bike owners (and, especially, California bike owners) is on this subject.

Thanks, all, again.

Larry



-- Edited by LRJ on Monday 18th of February 2013 05:07:48 PM

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The air/fuel ratio has too much air and not enough fuel. The fuel is what cools the cylinder down. The result of too much fuel is a wet/saturated spark plug, aka fouled plug.

 



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Maybe the header is thinner walled than the original stainless pipe. confuse

Maybe it's not even stainless, possibly mild steel?

Yuraku



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I am probably a lone voice here but I think a bit of header pipe "glowing" isn't a problem and, if you are getting normal fuel consumption and your plug colour is OK, I wouldn't worry!

Brian



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If your cylinder gets hot from running lean it then makes the header pipe hot. SIMPLE!

I had the same problem that you describe & all i did to solve the ''mystery'' was put a larger main jet in....Simple!

I fully re-built my engine so i have NO ignition timing problems or valve timing. Usually when someone advances the timing it is by moving the chain one tooth on the intake cam to make the valve timing advance.

The other way is to advance the ignition timing.Which can be done with a TT-R250 by moving the pick-up. This will only move a small amount though & would need a groove filed out from the mounting bracket to see any real change. For example i have uploaded a pic of an adjustable pick-up.

Posted Image

If your chain is stretched it would be retarded NOT advanced.

I honestly can't see anyone messing with the timing in these engines & the problem is THE MAIN JET IS TOO SMALL. I'm sure if you tried this your problem would be solved.



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LRJ wrote:

Thanks, again, TT-R250M, for your patience. I am a teacher, so I am well familiar with the sense of frustration that one has when people don't seem to want to try what you know will help or believe what you know to be true.

Larry


 That's okay. Guess you know what it's like being a teacher & all so no need to explain further.

A main jet costs just about nothing. In fact i have a standard #147 Australian main jet that I can't use or ''MY HEADER PIPE GLOWS RED''. You can have it if you like for the price of postage because I will never use it for this reason.



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LRJ wrote:

Header starting glowing after a minute or so with the choke on, stopped doing so when I shut the choke off and just let it idle, then started glowing again as I rode around a little. It definitely glowed brighter at higher revs than at lower revs.


If the header glows with the choke on then that tends to indicate that it isn't caused, at that point in time at least, by a lean mixture. What am I missing confuse 

Brian



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 Most carb equipped bikes built in the last 20-30 years use enrichers rather than a true choke plate. When the "choke" is on, it opens up an additional circuit that feeds extra fuel into the ventura. They only work under high vacuum conditions like idle and contribute very little additional fuel when the engine is reved up and on the road.

So in other words it's like leaving your bike idle high.



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Thank you.  I have ordered a #140 and a #146 (#145?), so I would think that I should be OK, but that is kind of you.  I don't know if it would help to change the pilot jet to a higher size, but I haven't been able to locate a Yamaha #52 pilot jet, anyway.  The discussion on this forum about the jet sizes (both orifice size and length) of different manufacturers (like Mikuni) has left me uncertain about the wisdom of trying jets from other manufacturers.

Larry



-- Edited by LRJ on Monday 18th of February 2013 09:54:53 PM

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I have been thinking about this. 

Why would a lean mixture cause the exhaust gases to be any hotter than a correct or rich mixture?

I would have thought the the more efficient the burn in the combustion chamber the hotter the exhaust gases would be?

I am happy to be corrected - just interested that's all wink

Brian



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This topic is getting quite technical, so ..................

As far as red headers are concerned, it is usually caused by the continued combustion of fuel burning in the header.

The exhaust coming out of the cylinder into the header does NOT find fresh air there to increase burning as some believe, but is a continuation of the combustion process because the cam has blown the slow-burning mixture out of the exhaust valve.

Insufficient ignition timing causes the combustion process to begin too late and not be complete when the exhaust valve opens, which causes excessively high exhaust gas temperature readings and red pipes.

Lean mixtures generally cause a "cooler" pipe because the mixture has less fuel to burn. i.e. lean/cold exhaust gas temperature.

A weakly fuelled cylinder will be cooler than a richly fuelled cylinder.

If the timing is correct, the headers will not be as hot as with late timing.

Martyn



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The size #50 pilot that you have now will be fine. Your not running hot at lower speeds so there is no need to change this. If you want more power you can but it's not necessary.

The Mikuni small round jets fit but the Mikuni large round will not be the right size. Sigma jets work with no drama's.

 You have to keep in mind that a Mikuni #140 jet in theory is the same as a Teikei #150 jet so be mindful of this. This is yet to be proven but this is a good rule of thumb.



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TTRfan wrote:

I have been thinking about this. 

Why would a lean mixture cause the exhaust gases to be any hotter than a correct or rich mixture?

I would have thought the the more efficient the burn in the combustion chamber the hotter the exhaust gases would be?

I am happy to be corrected - just interested that's all wink

Brian


 Running lean makes the engine run hot. This tends to lead to 'pinging'/'knocking'. This causes greatly increased cylinder pressures and heat, and can hammer bearings, crack piston rings/ring lands, burn pistons and valves, bend/break conrods (not fitted to a ttr), the list goes on...Believe me when i say this because my header pipe glowed red when i tried putting the standard jet back in! Same problem as this.

 

On the cam chain subject i do not think that anyone would try to advance the timing. I have heard of many people doing this to other engines but unlikely that your has been messed with.

Porting is where you remove all imperfections from the head chambers or make them a higher volume. This increases flow & engine cc therefore you have to increase the main jet.

You can increase your main jet size & what you need to do. Simple.



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Larry, you seem to have the right attitude and patience for getting to the bottom of this, and I look forward to more of your observations.

I have to admit, my first thought was "so what" - most bikes get hot headers and when it is dark enough and you happen to look, you notice it. Depending on the header material you can see the resultant discoloration in the header (some bikes have double walled headers just so you don't see this blemish). So I reckon that unless it is extreme, and the bike is also not performing well, it is not worth worrying about.

Regarding fuel mixture effects, the funny thing is that the exhaust gas temperature (EGT), when operating in the normal range, under load, with nothing wrong with the engine, actually reaches maximum EGT (and hence hottest header) at a mixture of approximately 14.6:1 which is near the "stoichiometric" air: fuel ratio for theoretically perfect combustion.

A tiny bit leaner than this and you get a lower EGT and the most economical cruise performance. A bit richer than this and you also get a lower EGT and maximum power. A little bit richer again and you get a further decrease in EGT, slightly reduced power but safe power for continuous wide open throttle running under full load. My dad was a farmer who also ran a small light plane aerial agriculture business, and this is not news to light plane pilots who actually have both a temperature indicator and a mixture control which they manually adjust for take-off, altitude, cruising etc. [btw, these old light planes were air-cooled and carburettored, just like our TTR250s].

OK that is all fine, but I for one, am unable to observe my apparent header temperature while running at near full power on a TTR250.

However, when you are running at light loads, possibly not in a perfect state of tune, it may not be so simple, and in some cases going a fair bit richer might relatively increase EGT due to continued combustion (or might not). Yes, retarded timing can increase EGT. Also (paradoxically) detonation and increased compression ratio can actually decrease EGT (but this would not be relevant when running at a fast idle).

Regarding jetting, surely the main jet number would have very little effect if this glowing header thing happens at low speeds and fast idling with the "choke" [aka low speed enrichment device] on?

However, if you manage to reduce the glowing header effect by changing jets, or mixture setting, that will be interesting. Glad to know that you are keeping with Yamaha jets so we can know for sure that a bigger number is richer.

By the way, a lot of people seem to think that screwing out the mixture screw a bit more will lean the mixture (as if the mixture screw was an air screw which it is NOT). I assert that more turns out means richer (but this is only relevant at speeds near idle).



-- Edited by brindabella on Tuesday 19th of February 2013 03:29:28 AM

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Thank you for your response, Martyn. You probably posted while I was composing.

If I understand you correctly, the real issue is a timing issue, and the valves are opening too early, relative to the combustion process. Which means that the exhaust valves are being "burned alive" while the engine is running. It would also mean that the engine is not operating efficiently or at maximum horsepower. Is that all correct?

Is the fix to reset the timing chain, then?

Also, why is a glowing header so common during enriched warm up (choke on)? Too much fuel to complete combustion in the cylinder? In which case, enriching the mixture only exacerbates the problem?

Larry



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Larry, I would prefer to think it was IGNITION timing that may be slightly out, rather than valve timing.

If you could "borrow" another ignition system as a test it would be a good comparison, but rather impractical.

Sadly, the TTR set up is rather unadjustable as far as advance/retard of sparks is concerned.

Not much help, sorry. no

Martyn

 



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Communication timing issues. I just responded to Martyn without seeing your response, TT-R250M.

Your suggestion is probably the simplest to try first, TT-R250M, and your personal experience adds weight to doing so. I must say, though, that I have not noticed any pinging/knocking. Perhaps someone more experienced than I could detect something, but It seems that the engine has run well.

Just to try to understand the different perspectives offered, could running lean lead to a hot engine, as opposed to a hot header?

Thanks, again, to all of you for your willingness to help and your patience in instructing an old dog.

Larry

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Just saw your latest contribution, TT-R250M. I am listening, and I appreciate your help. Thanks for the spark plug photos. I'll check mine, myself, today. As I said before, I'll give the main jet change a try. It really seems the only practical thing to do.

I do wonder, though, how many other North American riders are blithely riding around on their bikes, unaware that their bikes are running like mine.

Larry

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Thanks, again, TT-R250M, for your patience. I am a teacher, so I am well familiar with the sense of frustration that one has when people don't seem to want to try what you know will help or believe what you know to be true.

Larry

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I do see some of what you are saying brindabella but in THE REAL WORLD of TTR's it does NOT work like this. Most of what brindabella is saying is correct though. One thing that MUST be noted is that the TT'R is an AIR COOLED engine with no sensors

.............................................................................................................................................................................................................................
Regarding jetting, surely the main jet number would have no effect if this glowing header thing happens at low speeds and fast idling with the "choke" on?

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I thought that the 'choke' (enrichener) would have a cooling effect  on a ''glowing red header pipe'' but it seems in PRACTICE it doesn't. The 'CHOKE' is NOT the cause of his problem but would not be helping. As described Larry is running hot at higher speeds so a larger main jet will be needed. Also the fact that he needs to enrichen the mix should tell you something.

Using the choke on any motorcycle changes the fuel and air mixture. No 'choke' means that you have the "correct" ratio of fuel to air, which will give you the highest fuel efficiency and the least amount of wear and tear on the engine, as well as correct lubrication from the engine oil. Using a full choke means more fuel and less air are getting to the engine, which causes an engine to wear faster. Oil runs thinner and will not lubricate as well. As a result, the motorcycle is less fuel efficient and runs hotter. Leaving a full choke on for three minutes or less is fine to get the engine warm, but once the engine is warm, there should be no need for the choke. If your carburetor is dirty, and you are not using the choke, the engine may die. But, this is not a good excuse to keep the choke on. You are hurting your engine, and not helping to solve any carburetor problems. In this case, you should have the carburetor cleaned, jetted, and synced. This should solve your "choke" problem. Also, fuel injection motorcycles do not have a choke.


If your bike has fuel injection, then it's not a choke at all but rather a fast idle lever. The manufacturers just call it a "choke" because most people don't have the slightest idea of what a choke is or does, so they call it what everyone expects it to be called. If you have FI, then absolutely nothing happens other than having a fast idle.

In the Yamaha Manual it says, "Do not use the choke for more then 3 minutes as the exhaust pipe may discolour from excessive heat. Also, longer use of the choke will cause after-burning".

That said you would have to be way out of spec & the bike would run like crap (if it even runs) to be running hot from too much fuel (''after-burning-excessive carbon build-up'').

It is my experience that manual's are not clear whether or not it is a fuel screw or air screw because for example the ttr125 is called an air screw when in FACT it is a fuel screw.

In any case you need a larger main jet. SIMPLE!

You can also try to change the air/fuel ratio by lowering or raising the jet needle. The picture below will help with this.

044.jpg

 

 

 

 


 



-- Edited by TT-R250M on Tuesday 19th of February 2013 10:04:11 AM

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Rather than plagiarising articles from other forums, two posts by TTR-250M are consolidated here to save space.

This was taken from an article as it would take me way too long to describe this.

All the sections, to be found here, http://scootrs.com/tech.cfm?tip=tunecarb#a
and cover the same ideas in different ways; they all help.

 

Also, this article describes Troubleshooting and what to look for in carburettor settings,
http://www.4strokes.com/tech/4sjetting.asp

 

 



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Cubber wrote:

 

 

This topic is getting quite technical, so ..................

As far as red headers are concerned, it is usually caused by the continued combustion of fuel burning in the header.

The exhaust coming out of the cylinder into the header does NOT find fresh air there to increase burning as some believe, but is a continuation of the combustion process because the cam has blown the slow-burning mixture out of the exhaust valve.

Insufficient ignition timing causes the combustion process to begin too late and not be complete when the exhaust valve opens, which causes excessively high exhaust gas temperature readings and red pipes.

Lean mixtures generally cause a "cooler" pipe because the mixture has less fuel to burn. i.e. lean/cold exhaust gas temperature.

A weakly fuelled cylinder will be cooler than a richly fuelled cylinder.

If the timing is correct, the headers will not be as hot as with late timing.

Martyn


 I am sure Martyn is right. On all the big piston engines I operate (375HP/280KW and above) they all have EGT gauges and when I run them Lean of Peak they ALL run cooler.



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brindabella wrote:



What interests me is that TT-R250M appears to be saying that his well tuned TTR which happens to be fitted with a #150 jet from a SIGMA kit shows no evidence of glowing header pipe, BUT, with all conditions the same (??) except fitting a standard Yamaha #147 main jet, there is a very obvious red hot header pipe. I would be interested to know when this happens (eg after a full power run, when idling, during warm up, at night?). Now I would not know which is the richer out of those 2 jets, given they appear to be from different manufacturers, but perhaps the #147 is closer to giving the 14.6:1 air fuel ratio (leading to highest EGT) even though for practical purposes it does not appear to be the best jet for that particular bike setup. If this difference happens when idling though, I am completely baffled, as the effect of the main jet on idle mixture should be virtually undetectable.




 

I'm using Sigma #150 main jet with a Sigma #52.5 . More details below....

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Ported & polished head. (not the one on my shoulders)


I am from Australia, temp is usually 17-40 degrees
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Engine: 74mm bore/Wizeco high performance piston & rings
Exhuast: FMF 4Q muffler/standard unrestricted header pipe

Air filter: GYT-R

Altitude:930 metres (3,050 ft)

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Jets fitted.

#150 main jet on the last setting (top clip postition) Leanest setting (can't go down further with the standard airbox)

#52.5 pilot jet Love it awwawwaww

Air screw position: 2 & a half turns out

..............................................................

I know I'll be listening to FmF & all the major exhuast companies before anyone here!

 



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LRJ wrote:

I happened to use the TTR to commute to work early one morning (about 5 am--dark) last week and I noticed that the header pipe got a pretty bright red while warming up with the choke on. After easing off the choke and riding the bike with normal throttle, I leaned over and saw that the exhaust header continued to glow. I saw that it was glowing as I rode home late that evening. If I stopped the bike and idled, the pipe would cool and the glowing disappeared within a minute or so. Everyone to whom I subsequently spoke agreed that the exhaust header should not be glowing red. disbelief

My motorbike mechanic had just checked the spark plug while checking valve clearance a week earlier and hadn't seen the normal evidence of running too lean. I brought the bike back to him today, and he cleaned out the carb, checked that the jets were stock (#50 and #137 for yr 2000 North American models) and clean, adjusted the needle to the richest setting, and adjusted the mixture screw to 2.5 turns out. It now still glows red after I have been riding it, pushing it a bit. It doesn't glow while idling, and if I stop the bike, the glowing disappears. The bike runs really well (and ran well before the enrichment). I have the stock exhaust system and an unmodified air box--the engine is all stock. Granted, it is pretty dark at night where I live (in the woods, no street lights), and the glowing is not that noticeable in well-lit areas.

confuseDoes anyone have any other suggestions. Could this glowing possibly be normal and most people don't notice it, because they don't ride their bikes at night, or its not that dark where they live? After all, it does take some awkward movement to lean over and check the header while riding. Any thoughts or suggestions would be well appreciated.

Thanks,

Larry



-- Edited by LRJ on Sunday 17th of February 2013 06:20:00 AM


 

Please tell me how he is running rich using a Standard Yamaha (Teikei) #137 main jet (for the US) with the usual Standard (Teikei) #50 pilot jet?

Also why does he have to use the ''choke'' (en-richener) to en-richen his air/fuel mix? .... (maybe not relevant if it's not a necessity for Larry to use choke)

Why does it only glow red at high speeds?

Larry did not mention his bike running bad so why doesn't it run like cr@p if it is too rich?

Also as i have already mentioned i have had this problem using a Standard (Australian) Yamaha (Teikei) #147 main jet & solved the ''mystery'' by using a Sigma #150 main jet. The reason i tried using the Standard (Australian) Yamaha (Teikei) #147 main jet was to see the difference in jet sizes between Sigma & Standard Yamaha (Teikei) jets. Result: The Sigma #150 main jet is MUCH larger than the Standard Yamaha (Teikei) jet because i can NOT use the Standard Yamaha #147 main jet or the ''header pipe glows red'' TOO LEAN! . Also i have to have my jet needle at the leanest setting or it is too rich.

On top of that....

domski1 wrote:

I had a problem with my header glowing, poor starting and idling, it turned out that I had the incorrect main jet fitted and the idle mixture was slightly lean, I think that most ttr's will glow very slightly when they are on the choke in the dark though.


 



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 Brindabella - do you know what size jets you have fitted. You are in Australia right? If so i already know (assumed from older posts since you failed to fill out your profile)

OK here is the answer....

Standard 2011 bike, yamaha #50 pilot, yamaha #147 main, needle clip 1 step leaner, 2 to 3 turns out on fuel mixture screw (I think), runs well at 700M altitude, but who knows, maybe it could be jetted better.

It's no wonder that you aren't seeing your header pipe glow because a #147 main jet is slightly rich. Do you think that Yamaha would sell you a bike that is too rich if it causes as much trouble as you say? That doesn't make sense.



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ok, as one of the people who say, all other things being good, "running with hot exhaust gas is running with a complete burn, is running with a pretty good air-fuel mixture - so running slightly richer OR leaner will be running cooler", I will attempt to answer TT-R250M..

first, we are not talking about whether anyone's choice of jets is good or bad or really whether Larry's bike is running rich or lean.
one thing seems clear, his bike is running quite well, so surely the jetting can't be too far off.

what we are talking about is this phenomenon of a glowing header pipe.
we want to know when it happens, why it happens and if it matters.

sure we have people like me chucking around theories or mentioning maximum EGT at stoichiometric mixtures, and we have opinions on the net and experiences with cars which seem to agree, but then we also have some practical experiences with actual TTR250s to be considered...

Larry does not say that his bike needs the choke on to run properly, or that the header only glows when the choke is on - he says (but, LRJ please correct me if I misinterpret you) that when normally starting the bike, the choke is on from the cold start and after a while it glows, but when the choke is then taken off (at idle, when warmed up) the glow diminishes. Well actually, the choke is only compensatiog for poor fuel vaporisation before the engine warms up - the effect is really that the air fuel ratio is corrected to normal for the short period of cold running, plus the choke makes it idle FASTER (which is probably the main reason for the glow).

Larry also says that it ALSO glows under normal commute style riding, which is interesting. Personally I have not noticed this but I usually ride in day time, so it would not be visible. I am sure most of us have seen an exhaust header glow in the dark, so it is not that unusual.

What interests me is that TT-R250M appears to be saying that his well tuned TTR which happens to be fitted with a #150 jet from a SIGMA kit shows no evidence of glowing header pipe, BUT, with all conditions the same (??) except fitting a standard Yamaha #147 main jet, there is a very obvious red hot header pipe. I would be interested to know when this happens (eg after a full power run, when idling, during warm up, at night?). Now I would not know which is the richer out of those 2 jets, given they appear to be from different manufacturers, but perhaps the #147 is closer to giving the 14.6:1 air fuel ratio (leading to highest EGT) even though for practical purposes it does not appear to be the best jet for that particular bike setup. If this difference happens when idling though, I am completely baffled, as the effect of the main jet on idle mixture should be virtually undetectable.





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Brindabella ...I think your missing a vital point in this.

 

 

LRJ wrote:



 I checked everything again last night after switching back to an older, original, air filter on the off chance that the newer one was more porous to air. Header starting glowing after a minute or so with the choke on, stopped doing so when I shut the choke off and just let it idle, then started glowing again as I rode around a little. It definitely glowed brighter at higher revs than at lower revs.


Thanks, all, again.

Larry

 


 



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Also no company brings out a trail bike that glows at the header pipe!

Maybe you should have read the choke warning too...

In the Yamaha Manual it says, "Do not use the choke for more then 3 minutes as the exhaust pipe may discolour from excessive heat. Also, longer use of the choke will cause after-burning".

Obviously they don't want the pipe to discolour!

If you have a YZF450F that has a titanium exhuast & valves with a Nikasil cylinder coating then this would be fine!



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OK guys - I have cleaned up the thread a bit so let's stick to the debate and not get personal or SHOUT in responses please. 

There is some really useful stuff in here but I still can't get my head around parts of it so let the debate continue and maybe it will all sink in.

All opinions welcomed!

Brian



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Wow! I didn't want to start a fire fight. Again, I am most appreciative of everyone's contributions, perspectives and opinions. However, I want to clear up what appear to be some misunderstandings of my bike's condition. I hope that I didn't give the wrong impression, but the following are the facts:

1. I don't need to use the choke while I am riding the bike. I only need to use it to start the bike when it is cold. I don't leave the choke on full for more than a minute or two (during which time the header starts to glow), then push it in to the minimum level needed to keep the bike running until it is fully warmed up. When I am riding the bike, the choke is not on.

2. Although the header glows brighter at higher revs, it does glow at lower speeds (like around 1/8 throttle), but it has to be pretty dark to see this.

3. Right now, the jet needle is set at the richest setting, and all of the above still apply.

TTR-250M, given that I do have a hot header at low speeds, would you recommend a bigger pilot jet, as well? If so, given that my system is completely stock, what would you guess would be an appropriate size (and manufacturer) of pilot jet to try?

I am with you, Brian, besides getting my bike to run the way that it should, I would really like to understand a lot more about this topic than I do. I am going to go back and reread all the posts to see if I can understand better what everyone is saying.

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That is the understanding that i had of your bike.

I cannot say what pilot jet would be perfect for your bike because I have no idea what your current elevation/oil used/average temp/humidity/cylinder size or whether or not the head has been ported. What i can say for sure though is that the standard #50 Yamaha (Teikei) jet should not be causing this unless unseen mods have been done. The older bikes are running fine on a #48 pilot jet so I don't see a problem with the #50 pilot jet.

The ''running hot at lower speeds'' can be put down to the fact that the main jet is too small & causing this because you only have be at 3/4 to full throttle for the main jet to affect it.

Thanks for making things clear for others Larry thumbsup.gif

 



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Since nobody seems to believe me i have rang my local mechanic. He knows more about these bikes than me as he owned one for years & this is the result...

Me: Hello, just thought I'd say thank you for your great service! The head porting you did made HEAPS of difference & the bike runs like a dreamawwawwaww It was the TT-R250 that you did some of the head work to.

Mechanic: Yeah? Awesome! great to hear. If you have any questions or trouble bring it in to us & we'll sort it.

Me: Thanks,I'll keep that in mind.

Now the interesting part....

Me: I know this will be a controversial subject & probably all dumb questions but... If your header pipe is getting hot & glowing red is this normal?

Mechanic: No way! If your header pipe is glowing red at any time you are running WAY TOO LEAN! Water-cooled ATV's can glow red after a long ride thrashing them but at NO time should a TT-R250 glow red at the header pipe!

Mechanic: What jets are you running?

Me: Well actually it's not my bike it's someone else's. It is a standard TT-R250 running the Standard US jets #50 pilot & #137 main jet.

Mechanic: Wow that sounds lean but you have to take into account elevation etc but as I said.... AT NO TIME SHOULD THE HEADER PIPE GET HOT!. This could burn a hole in the piston or worst!

Me: Okay that confirms my theory but if it was running rich would it glow at the header pipe?

Mechanic: If the bike was running rich it would smell like unburnt fuel & run bad. Also the plug would become fouled/black. This would NOT be causing it to get hot at the header pipe though.

Me Okay, thats what I thought.

Me: It's happening at high speeds past 3/4 throttle. So would you suggest a 2-3 size increase in main jet?

Mechanic: First I would be checking that the carby is not blocked. If it still does it then increase the main jet by 3-5 sizes depending on your elevation/etc. but given the fact that it's glowing red at the header pipe I'd say 5 sizes up on main jet. You can try to change the needle position but this won't help by the sounds of it.

Me:Okay roughly what I thought. Thanks heaps!

Mechanic: No problems if you have any more drama's give us a bell.

Me thinking: Okay I've probably pushed this subject far enough & made myself look stupid enough by now. biggrin

Me: Cheers mate,see ya.



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