A forum for owners of Yamaha TTR250 trail and enduro bikes!

Hi Giles

Another coincidence! I have had two TTRs recently with the same symptoms and it turned out to be blocked or partially blocked pilot jets.

I invested a year or so ago in an ultrasonic cleaner and it works brilliantly on carbs cleaning the internal petrol ways as well as externally. The TTRs both started and ran smoothly after their carbs had the treatment.

Regarding the pilot jet, I haven't worked out a way of getting at it without taking the carb off - sorry!

You need to get it out and soak it in carb cleaner and give the carb body a good spray of the stuff as well. That should sort it.

If I get the chance (Mrs TTR has got me on DIY duties today ) I will do a show and tell 

Brian

Pics as promised!

Don't forget the advice on taking out the carb here http://www.ttr250.com/Removing_carb/TTR_carb_removal.htm

These are all the tools you will need for a basic strip:

Start off by removing the two screws and taking out the diaphragm and check it isn't damaged. It makes sense to replace the two little O rings (part number 5Y1-14397-00-00) when re-assembling.

The pic below shows the carb stripped as far as you need to go if just cleaning jets. My advice is NOT to take the float assembly off without very good reason as you risk breaking the support post arrowed in red. The retaining pin is usually very tight 

Pink arrow is airscrew, green arrow is pilot jet, blue arrow is main jet and its support.

Most carb leaks seem to occur because the float bowl gasket (part number 4GY-14384-00-00) gets flattened over time. For the amount of hassle involved in putting everything back together only to find a leak, I advise putting a new one in if it looks "flat!!

 

Make sure you don't lose the little brass thingy arrowed in red below. It has been known for them to fly across the garage (never to be seen again) when blowing out the float bowl with the airline 

 

Not much more to add really other than to pop it all back together and wind the airscrew out 2 to 2.5 turns before putting the carb back on the bike 

 

Thanks all for the advice so far.

Full of confidence now, I'll get stuck into the carb at the weekend. If any idiot can do it, this idiot can!

carb first, then valve check if that fails to cure it.

Giles

Just had this email from John. I absolutely accept that the carb info on the FAQ and elsewhere is confused and contradictory.

John gives a simple solution to the "bogging" on the Australian TTRs - see below. Feedback would be appreciated. I know of a few other blue TTR owners who feel that their bike is over-jetted with the 147 main jet.

Brian

 

I noticed in your site and other forums, a mass of info about ttr250 carby problems (some of it contradictory).  I was looking because my

2011 aust model had a "flat spot" / "stumble" / "hesitation" (the English language doesn't seem to have the right word). So i waited until it was definitely run-in (2000km), documented the problem for myself (1/3 throttle eg 60-65kph 4th gear very slight acceleration or 80-85kph ditto in 5th gear with 13T/44T with absolutely everything standard, exhaust pipe completely untouched, despite the bike shop telling me to hacksaw off the end of the header which has a small bulge/restrictor/whatever, nothing done to the airbox, standard australian #50 and #147 jets and mid needle position, problem not particularly dependent on atmospheric temp/pressure, normal fuel).

then I made just one change - I moved the needle clip up 1 (ie dropped needle to a  LEANer position) from 3rd clip to 4th clip counting from bottom).

This single change pretty much completely fixed the problem for me, here in Canberra at an altitude of 600 metres above sea level.

 

John

Hi, I am the guy who ttrfan quoted.

I would add that, I test rode a 2nd hand ttr and also a new demo ttr (but which had the header restrictor removed) before I bought my own new ttr, and they both had a very similar "bog" to mine.

Ideally, I would have liked to also try richening the needle by one clip to assure myself that it then got worse, but I couldn't be bothered, because as I said, leaning it worked for me at my location (only a shadow of the problem remains).

But I would like to point out that if your riding location is near sea level and your area has days of high atmospheric pressure, you might not want to go lean (though I would be surprised if going rich would improve things, all else standard).

In answer to davecambo, my fuel consumption is variable but 22km/liter is easy enough, so a range of 160km to reserve is easy enough (depending on how brim full the tank was to start). By the way, I measured the fuel remaining after hitting reserve once - there was 1.2 liters easily available, then another 0.7 liter with lots of rocking the tank from side to side etc.

I sure would love to hear from anyone who reckons either there is no "bog" as I described, or that there is some other way to get over it with an otherwise standard bike. I met someone round here a while ago who had two ttr250s - they recognised "the flat spot" but didn't particularly care about it (as full throttle acceleration is fine), whereas I found it annoying in traffic and when making small speed changes when cornering on the road.

Incidentally, if someone does want to fiddle with their needle clip position, it might be useful to know that you can get the needle out without undoing the phillips head screw on the throttle rocker spindle which the manual says to undo (on my bike it was very tight and I was scared of stripping the screw head).

Hi

I'm after the O rings that seal the pumper diaphragm plate (part number 5Y1-14397-00-00).

Can anyone recommend a source for these parts in the U.K.

Cheers

Since I not' have any starter that works, it is necessary for me to lean on the kick!!! She starts up not. I have ignition there has gasoline,s»Ï8¼ The cutting circuit is OK the faucet of gasoline is ONE filters It to Air is nine.
The healing ones of humidity are empty and clean.
someone will be able to give some measures in turn:
I live wealth, lives has air spring (of slowed down) and strap of the cable of accelerator.

Photo pics






Merci d'avance

alain fermer la completley vis, puis tournez à 2,25 tours de la position fermée. Si elle fonctionne encore agitée, dépouiller l'completley carb assurez-vous que tous les jets sont propres et vous pouvez voir à travers chaque trou, puis essayez à nouveau. Ces glucides sont sales, exécutez un filtre à carburant

you can get them as individual parts from cmsnl.com , although they are quite expensive hth

Dave

Hi All, can anyone recomend a uk dealer for carb parts, such as 4GY-14198-01-00 gasket, 4GY-14105-00-00 pilot jet, 4GY-14384-00-00 gasket, 4GY-14940-00-00 diaphragm assembly, or do i have to get them from U.S.A/EURO dealers?? Cheers..

I am not usually surprised by what I find in old TTR parts but this float bowl made me chuckle 

Looks like mud but it must be fine rust particles that have found their way through the filters.

This carb is getting a very thorough clean 

This is a strange one. I have been experiencing some intermittent carb problems the last few times I've had the bike out. ('93 OE)

After about twenty minutes of normal riding the carb doesn't want to give me anything other than idle or full bore. If I tickle the trottle it bogs and dies. I've  had to ride home a few times full throttle, riding the clutch. I've had the carb apart for a clean as I suspected a blocked jet, but there were no noticable blockages.

The float valve doesn't seem to be stuck, bent or incorrectly assembled either, so I'm absolutely stumped.

I've also checked the tank venting and that fuel was actually flowing, all good.

The symptoms are like flooding but I have no idea how it could be flooding.

Anyone came across this issue before? Any suggestions are welcome.

I had to push it 2.5 miles home yesterday, along railway track ballast and every bit of me aches.

I'm very tempted to break it, as I'm a bit skint and an expensive repair is out of the question.

I really hope I've missed something simple as this is a nice bike to ride. Please help an aching man with hurty feet and a knackered bike.

Thanks for the quick response Brian.
I'm going to pull it apart again after dinner.

The breather/drain pipes and their NRVs are shown on the right of the picture.

That's a good point, forgot about the breathers and ventricles etc. It's in bits now, just need to look at everything in detail.

I have the carb in bits on the bench, I just haven't had time to give it a proper inspection. I will post the results when I'm done though.

Well I finally got mine fired up yesterday!

Big delay due to knackered back, maybe from 3 days bent over TTR + pushing FJR about with rather rusty discs.

Back healed, both bikes fired up and TTR sounded smooth. Only run up for an oil warm up, started extremely quickly and idled very smoothly.

SWMBO wanted taken out so no run report yet + weather forecast not brill.

Gordy

More likely the float needle is sticking down. Have you tried tapping (might need to be quite hard!) the float bowl with the end of a screwdriver whilst the petrol is on to see if it stops the flow? 

Brian

Got it. Sticky float valve was causing it to either flood or run dry. Just been testing the valve with the bowl off and it works again. I suppose it also doesn't help that the lad I bought the bike off had the float hinge upside down.

 

:Edit:

Just took it out to get it dirty.  It's running fine apart from a little bogging when just coming off idle, but I suspect that this is due to the air screw being reset in correctly. I'm going to have a fiddle with it later.

-- Edited by BaronGreenback on Thursday 21st of March 2013 04:41:42 PM

Hello all. I recently purchased a 1999 ttr 250. The last time i worked on it, i cleaned out the carb. After i assembled the bike and turned the gas on, it would flow out of the overflow tubes. I got to work on the bike again today. I took off my floats and i noticed that the point of my needle valve broke! I took the little bit out and it is still able to seal with a broken tip. I also bent my floats down about 1/16 of an inch so the floats raise higher to make up for the broken needle valve.

how does fuel level in the carb affect the carb's performance? Also, some gas still comes out of the overflow tubes when the bike is off. I think the vibrations from the motor bumps the valve into place and stops the leaking because it won't leak when it's running. Also, I am trying to adjust my fuel screw. I have it set to 2 turns out. When I hit the throttle and the rpm's go back down, the engine pops and sputters back to idle. is it too rich? also, if i blip the throttle from idle, it will either stall or take a second to catch up. is this normal or does something need to be fixed?

also, i'm kind of afraid to ask but is the tail light suppost to function? all mine does is light up with the headlight. it doens't glow brighter when brake is applied.

 

 

-- Edited by yamaha42 on Thursday 28th of March 2013 12:03:28 AM

Oops

Perhaps that's the reason the gas is leaking. 

More expense.

Yuraku

although these blue TTRs all look much the same to me, your bike is probably a US model
- in particular one without blinkers etc which is not usually road registrable.

I believe these bikes have a taillight yellow wire which goes nowhere.
Also they don't have the switches installed near the brake foot or hand lever.

so have a look - if that is the case, the brake light will never work unless you do an upgrade.

Lowering the float level would make it slightly leaner, all else being equal.

The symptoms you have (leaking while on the stand, ok when riding) are typical of a worn float needle+seat set needing replacement. so why not buy a new one, as it is broken anyway?

But if you really want to do it on the cheap, you MIGHT be able to improve the sealing by carefully polishing the float valve needle to get rid of any little ridges where it contacts the float valve seat.

Bad luck Rodge but at least you kept going!

Both pipes running down from either side the carb (this includes the short on on the LHS that clips onto the engine breather pipe) should have one-way valves fitted. 

The pipes the other side the T pieces run up to the airbox and are open. Over time dust etc can get in these and fall down onto the one-way valves and can stop them working. Worth checking on anyone's TTR.

Brian

In addition to what Brain is saying, there is one pipe that runs back to the oil seperator/emmision unit at the airbox. This should have a one-way breather fitted to it also.