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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> Intake manifold stub troubles!
Post Info TOPIC: Intake manifold stub troubles!
Andy_C


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inlet manifold...
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Hi all

been doing my little upgrades to my old oe and discovered a mystery,look closely at the picture and you will see that the rubber tube which runs from carb to engine inlet port has come apart from the aluminium part that bolts to the engine barrel.

Now I'm making the assumption this is incorrect and the 2 parts should be fixed together as 1.

Not having stripped my bike down this far before I wondered if this was broken or that the 2 pieces are meant to have movement,all my experience tells me this part is broken but thought I 'd ask you knowledgable people if this is correct.

I assume I need a new one... where can I get one,I look towards brian...

Or could I seal this one with high temp silicon and put a jubilee clip round it?

Think I'd prefer a new one but want to get the bike on the road quick.

Thanks for the help.

DSCF9297.JPG 



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TTRfan


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There seem to be quite a few threads about this inlet stub. The rubber should be bonded to the metal stub but, over time, it all goes a bit Pete Tong cry

In terms of repair, this is what it says in the FAQ:

Carburation problems? Check the rubber inlet manifold between the carb and the cylinder head as it may have come apart. The aluminium part that bolts to the head is tapered so gluing the rubber back on isn't easy. When the rubber comes adrift it sucks air into the engine upsetting the fuel/air ratio and causes poor running. It's also a very common fault and I've seen it on 2003 models. To glue the rubber back on you will need to remove the airbox, carb and inlet stub. Then clean it as best you can with a solvent that evaporates - meths, acetone etc. Then use an epoxy adhesive to coat the stub and push the rubber back on. Clamp end-to-end and put a jubilee clip (hose clip) around the glued area but not too tight. When the glue has dried (24 hrs is good) drive a couple of self-tapping screws through the jubilee clip, through the rubber and into the aluminium stub. If you're fussy, Dremel the ends of the screws inside the inlet stub.

 



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barra8


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Looks like Brian's got this one covered....I have two repaired boots & when the vulcronizing breaks down from heat it does what your pic shows. As Brian says you can use epoxy adhesitive to re-bond it back together. It may to do as Brian suggests & or put some high temp silicone over the epoxy. (Makes it look good too :). Never had a problem with a repaired one but bought the new one to be sure.

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

Jarrah.



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Andy_C


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Thank you for that gentlemen, confirms my thoughts and gives me a course of action to rectify the problem.

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barra8


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Andy_C wrote:

Thanks for that generous offer jarrah but I'm pretty confident I can seal the original up, If the fix don't last I may contact you.

That bloody air filter box is a sod to get back in, any sort of knack to it?

 It will be here if you need it.

The airbox can be a real pain in the butt. This is how i do it.

First take off the frame support off. (located left side)

Now it ''crams'' in & not a good fit. In most cases expect to scratch your frame.

Unless....

You trim the airbox like i have done so it fits better.

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

Jarrah.

 



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TTRfan


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Intake manifold stub troubles!
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If it goes wrong (hopefully not!) and you need a new stub quickly Adam, Steve has them in stock - see here

Brian



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Charlie D2


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Inlet manifold mismatch
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Hi All Which way up does the Inlet Manifold fit please? Mines got the 'notch' at the Carb end pointing down which works cause it lines the Carb up with the Airbox. Trouble is when I look inside the Manifold it doesn't line up with the inlet port!!!!. I've tried turning the Manifold through 180 degrees & it lines up fine with the port but then it's way out to the Airbox! Curiously I understand I do not have a genuine Yam Manifold could this be the reason? Cheers & a Merry Xmas /HNY to all



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AndrewM


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Did you order it from china of ebay? I have 2 the same i complained and they gave me a full refund.



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TTRfan


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Carb notch on the inlet manifold should face upwards!

To see what the genuine Yamaha part looks like see here

Buy Chinese buy twice no

Brian

PS Welcome to the forum AndrewM biggrin

 



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Charlie D2


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Ah ha! thanks Andrew & Brian that's very interesting. So when I put it on notch at the top it lines up with the port, does that mean the Manifold Carb end is in the wrong place?

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TTRfan


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Sorry if I am being dense but what exactly is going wrong - is it that the carb doesn't fit in correctly with the notch at the top and, if so, does it point the carb in such a way that it doesn't fit into the airbox rubber?

Any chance of a pic to show what's happening?

Brian



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Charlie D2


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Sorry for the confusion Brian. When the Manifold is fitted notch up & the Carb is fitted it does not line up with the airbox rubber. I will take a picture ASAP
Peter

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TTRfan


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If you have the standard TTR carb and airbox/rubber then surely you must have the wrong inlet stub? Can't see what else it might be confuse

I am curious as to how this has happened. Have you recently bought the bike with the carb loose? If not and the carb was on OK then it should go back on OK. What am I missing?

Brian



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Charlie D2


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Hi Brian I bought the bike with this manifold fitted & noticed the Manifold problem when took the head off. On closer inspection I can see the rubber is badly moulded & the metal insert has split in it. Time for a genuine Yamaha part I think, I'll get my order in asap

Thanks for your help

Peter



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Charlie D2


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Got the Yamaha Manifold today (thanks Brian) and I can confirm that the 'knock off' Manifold that was fitted to my bike has been made incorrectly with the metal flange moulded 180 degrees out of position. Bottom line don't buy cheap c**p it's not worth the risk.

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TTRfan


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Haha - I got caught out as well! Whilst doing the annual Totally TTRs stock take I found that I had bought a Chinese copy of the inlet stub to check it out. It was cheaper than I can buy the genuine article at trade price so was worth a shot. I never actually got around to fitting it so didn't find the problem myself.

The photo below shows the carb notch way out no

Brian

TTR250_carb_inlet_stub1.JPG

 



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Charlie D2


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Yup that's the same as mine, is it badly moulded inside as well?


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TTRfan


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Mine's not too bad on the inside. Not heard back from my eBay seller (begoniasale) though no

Was this the one you bought?

Brian



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AndrewM


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Intake manifold stub troubles!
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 Yes thats who i got mine from. The quality was not bad, just inlet doesnt line up, unless you put it on upside down, then carb does not line up.

 

Image3.bmp



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TTRfan


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RE: Inlet manifold mismatch
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Did you get your money back?



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AndrewM


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Yes i did get my money back. that was in jan 2014, i cannot beleive he still selling them wrong.



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leigh


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Inlet stub?
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Hey all

I need your collective help again :)

Bike has been playing up a little. Had the carb out again, cleaned everything, nothing seemed wrong  the only part that hasn't been replaced is the float needle  I did a full rebuild of it 6mths ago. Always ran perfectly.

 

Lately has had a bit of racing/low idle problem, back off the throttle and sometimes it idles too high then dies down to normal or too low and pop. It stalls. Loud pop from the intake. Runs fine at all other throttle settings. It maybe a little low on power. 

 

Sometimes its fine sometimes it's not. Just replaced the needle clip set. Had standard main with clip set one step richer. 52 pilot jet. Nothing was loose in the carb and it did not seem to have any play in the slide linkage  

Do you think it's drawing air? I did check the stub but didn't take it off. I will tomorrow night and have a proper look

Before this turns into a pull the carb out 50 times for me. Is there anything else I should check while I'm at it?

 

 



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petenz


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If you want to find a inlet air leak....
spray some engine start around the intake boots while it's idleing
if theres a leak it will suck the engine start in and rev up for a second
or to....





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leigh


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Thanks for the tip.

Yep it's the stub. The rubber has split where you do up the hose clamp.

Brian. How long does postage express/airmail take to Australia?



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TTRfan


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Intake manifold stub troubles!
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leigh wrote:

Thanks for the tip.

Yep it's the stub. The rubber has split where you do up the hose clamp.

Brian. How long does postage express/airmail take to Australia?

I am surprised how quickly airmail gets to Australia - it could be as little as 5-6 working days if the star signs are in your favour!

But my guess is that you would be able to buy the stub locally at less than it would cost in total from the UK. 

Brian



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yamaha42


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Well, it's been a while everybody! I just wanted to let all you fellow TTR enthusiasts that all has been well except for a split intake stub. I discovered this one day when I went to adjust the needle in the carb, and the stub separated in two when I tried taking the carb out. No worries, I simply ordered a new intake stub, gasket, and bolts. I got the job done in about half an hour, and now I'm confident that I'm not sucking in any unwanted air! :)

Old vs New

intake1.jpg

One half of the stub still attached to the carb...

intake4.jpeg

 

It looks rough but i did clean off this surface before installing the new boot.

intake2.jpeg

 

The stub with a nice new o-ring.

20150616_142711.jpeg

and here is the nice shiny new intake boot on the bike

intake3.jpeg

 

 



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ttboof


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RE: Intake stub troubles!
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great pics really shows what's a bit of a hard problem to diagnose at times , thanks for posting



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TTRfan


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Intake manifold stub troubles!
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Genuine Yamaha OEM and after-market inlet stubs are available from Totally TTRs - see here



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ttboof


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I've put a cable tie around the stub so far it's still OK 

Looking at them idling the inlet  pulses work at pulling the two pieces apart I'm hoping the cable tie keeps them together by stopping the movement 

 



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