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The TTR250 FAQ web pages -> TTR250 -> Carb stuff -> Carb leaking petrol?
Post Info TOPIC: Carb leaking petrol?
pauls ttr


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Carburetor leaking help!!!
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can any 1 give me any advice on my leaking CARB Please!...



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chrisstdt


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Cant realy see any leaks in the pics but the drawing is of the diaphram ,mine leaked from there and the jet didnt squirt fuel on full throttle even after i cleaned out the jet so i got a new diaphram and two orings from brian and it sorted it

when i pumped the throttle you could almost see fuel being pushed out and brian told me to flat off the surface on the bottom diaphram plate with wet and dry as they can sometimes leak after new o rings are fitted

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yamaha42


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Carb leaking petrol?
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My carburetor was leaking at the diaphragm cap, and a new set of o-rings and a new diaphragm sealed the leak up nicely.



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TTRfan


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RE: Carburetor leaking help!!!
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Seems like it was just a sticking float valve eh Paul?

Nice simple fix - tap on the float bowl with the blunt end of a screwdriver and go ride it biggrinbiggrinbiggrin

Brian



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pedrosan


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Evening chaps/chappettes.

First of all; great idea to have a sub category for carbs.

Secondly; a carb leaking quite a lot of petrol whilst running/idling/after stopping (although this could just be run-off), does that sound like a sticking float valve or something else? my carb is in bits and all the jets look clear, although it's hard to tell, and the inside looks ok. I'm reluctant to reassemble it all until I find out what was causing it...

Cheers,

Pete

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Pete Brown

Keighley, West Yorkshire

'94 Yamaha TTR 250 Raid (with Open Enduro headlight, grrr...)

'54 plate Suzuki GSF 650S (Bandit)

Previously Yamaha YBR125, Yamaha TY125, Yamaha TY250
TTRfan


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Hi Pete

Just brainstorming possible causes:

  • Incorrect float level
  • float bowl gasket needs replacing if it's hard/perished/flattened
  • diaphragm and the 2 small O rings not sealing and may need replacement
  • sticking or worn float needle assembly

Replacement parts are readily available off the shelf wink

Brian



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pedrosan


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Cheers Brian. I've got new gasket and O rings, I've cleaned it all out, the float seems to move freely, I think I'll try it back together now. Fingers crossed...

Pete

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Pete Brown

Keighley, West Yorkshire

'94 Yamaha TTR 250 Raid (with Open Enduro headlight, grrr...)

'54 plate Suzuki GSF 650S (Bandit)

Previously Yamaha YBR125, Yamaha TY125, Yamaha TY250
petenz


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leaking carb..
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Got fuel dripping off the bottom of the fuel bowl....

bike still runs fine...

quess I will have to pull the dam thing apart....



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Yuraku


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Muck in the bowl preventing the needle shutting the supply off? confuse



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TT-R250M


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Yuraku wrote:

Muck in the bowl preventing the needle shutting the supply off? confuse

 If the float bowl gasket is working as it should it would be coming out the overflow, not the bowl.

In addition I would suggest to check the accelerator nozzle is not blocked, the diaphragm is not cracked/perished and the two O-rings are not perished. More info HERE.

Enjoy!

Jarrah



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petenz


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TT-R250M wrote:
Yuraku wrote:

Muck in the bowl preventing the needle shutting the supply off? confuse

 If the float bowl gasket is working as it should it would be coming out the overflow, not the bowl.

In addition I would suggest to check the accelerator nozzle is not blocked, the diaphragm is not cracked/perished and the two O-rings are not perished. More info HERE.

Enjoy!

Jarrah

 That sound like a lot of work.... think I will just buy another bike...... lol

Could well be a perished what not... haven't used it for 9 months...

only turned over about 5 times before it fired up... didn't even have to

charge the batt... got to love those Motorbatt's...

Got to have it going for Dalethorpe in 3 weeks...



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TT-R250M


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petenz wrote:
TT-R250M wrote:
Yuraku wrote:

Muck in the bowl preventing the needle shutting the supply off? confuse

 If the float bowl gasket is working as it should it would be coming out the overflow, not the bowl.

In addition I would suggest to check the accelerator nozzle is not blocked, the diaphragm is not cracked/perished and the two O-rings are not perished. More info HERE.

Enjoy!

Jarrah

 That sound like a lot of work.... think I will just buy another bike...... lol

 Much better than having to rebuild the whole bike n if it's not another TTR250, you will have more work than just fixing the carb. biggrinbiggrinbiggrin

Good luck!

Jarrah



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petenz


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Is there anywhere that sells a carb rebuild kit for the TTR250
or do i have to get the parts from yamaha ?

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TTRfan


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Hi Pete

TTR250 carb service/repair kits are available from Totally TTRs here.

These are the parts most frequently found in need of replacement by owners:

- Carburettor float bowl drain screw set (the original rounds out if left too long)

- Carburettor float bowl gasket - probably essential if the carb still has the original in it

- Carburettor diaphragm and the two small O rings that sit alongside the diaphragm (NB - smooth off the face of the diaphragm "plate" on a bit of wet & dry paper placed on a dead flat surface to get rid of any dirt/corrosion before putting it back on) - easy enough to test the diaphragm BEFORE you strip the carb - see Jarrah's helpful posts on this

- Carburettor float needle valve set - usually only needed if leaking

Hope that helps.

Brian

 



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petenz


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found the leak...
only happens when yer twist the throttle..
forces the fuel out passed the 2 tiny O-rings
in the diapham housing... must be a block somewhere...
The 2 O-rings don't look to great either....


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TTRfan


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Easy fix then Pete wink

Don't forget to flat off the diaphragm cover with some fine wet and dry on a dead flat surface before replacing with new O rings to make sure it has the best possible chance of getting a good seal.

Brian



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WheelMan


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Picked my TTR up on Friday, and discovered that petrol was dripping out onto the van floor when I drove round corners. Not much but every time. Not got around to looking yet, but will have a go later today.

Any clues ?

 

Cheers



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TTRfan


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If it's not leaking between the tap and the carb then it's most likely the float bowl gasket and/or, less likely but possible) the diaphragm and its 2 small O rings.

However, it depends on the angle of lean in the van etc. It may be that it doesn't leak again once back on terra firma?

Brian



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WheelMan


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Thanks Brian.

Yes, on dry land it doesn't leak unless I wiggle it about. In th van it was secured in a front wheel steady thingy which I borrowed from work, so was vertical.

It was almost as though it was dripping out of an overflow. hmm

Hope to wip the tank off later today if I get a chance.



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TTRfan


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If the petrol is coming out the overflow then the float level might be a bit high....



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PlumasDude


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Thanks folks for all the helpful info on this post. I have a question about gas fumes in the garage. As the weather gets hotter I get more gas smell. There may be a very small leak in the carb but if so I can't find it. Is this flatulation a common experience with this carb? Or should I be looking for a leak?

In stripping the carb previously I found the tank shut off valve doesn't quite shut off, need to fix that, but the carb looks good. So the shut off is letting some gas by and I'm guessing that as my garage heats up during the day the gas in the float chamber is expanding and gassing out the overflow or elsewhere. Older bikes (and real old cars) used to get smelly in summer but not my newer YZ or TTR125.

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TTRfan


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Carb leaking petrol?
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Old carb rubbers.JPG

These are the usual culprits! I have just stripped them out of a carb that has been standing unused for a long time.

The float bowl gasket was hard and flattened. The diaphragm had fused to the carb body and had to be prised off plus the two small O rings by the diaphragm had seen better days. The carb wasn't leaking from the bowl but it is worth putting in a new gasket  to save another removal and strip down to replace it later. However, the carb was seeping petrol from the diaphragm cover so I have replaced the diaphragm and O rings. I tried the cheapskate method of just replacing the O rings first but a test fill of petrol showed it to be still seeping so the diaphragm had to be replaced as well.

A closer look at the O rings show why I thought they might have been the only culprit.

Old carb rubbers - small O rings.JPG

Before I removed the carb I test ran the TTR and it would start and run for a few seconds and then stop. It wouldn't react to the choke or throttle. Classic symptoms of a blocked pilot jet and, yes, when I took it out I could see it was partially blocked. I have given it the "copper wire" treatment and hope that I have solved the problem. If not, I will be fitting a new pilot jet! Life is too short for sorting out plugged pilot jets...........

Brian



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petenz


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leaking carb..
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the dam thing is up to it's old tricks again...... leaking fuel from somewhere....
Still runs perfectly...
This is the second time.. not going to give it a 3rd chance .. after all these things
seem to have a histroy of being more trouble than they are worth..

So will put the kosco flat slide on & see how it goes...

 




Pete



-- Edited by petenz on Sunday 21st of February 2016 11:17:40 PM



-- Edited by petenz on Sunday 21st of February 2016 11:25:53 PM



-- Edited by petenz on Sunday 21st of February 2016 11:40:06 PM

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Markvan


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Intermitted carby overflow leak
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Bike runs and starts fine , but lately after sitting for the night on the side stand (which makes the ttr lean heaps) i stand the bike upright to start it. Before i start it i notice a little bit of fuel leaks, but stops leaking,  from (im guessing the overflow) does that tell me the : needle and seat: are working ok but the float level is abit out. Carbys never been off with about 35,000 kms mainly road use. Will look next time to try and see which pipe it comes out off. Thanks. 



-- Edited by Markvan on Wednesday 25th of May 2016 07:35:05 AM

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mossproof


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CCM 644 s (with the Suzuki dr650 engine) were/are prone to this due to the excessive lean angle on the sidestand. I seem to remember it was float height related, but the real problem is the angle of lean - compare with when the bike is lying down - the float only works up/down in the bowl, not side to side, so when "up" is nolonger up but "sideways", if you see what I mean, the float can't work correctly to give the right fuel level.

If it was the needle valve sticking, there would be a constant leak stopped only by turning off the fuel tap. I put a block of wood under the stand in the garage and look for a suitable slope /kerb when out. As long as the breather pipes are clear, it's no problem, but if they're blocked it could lead to flooding the head and combustion chamber leading to watering down (surely fuelling down?) of the oil and hydraulic lock when trying to start, but your quantities sound quite small so I wouldn't worry about it.

Ride safe,
Simon.



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Markvan


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Thanks. pretty sure mine only does it when sitting overnight. But i will try the block of wood and report back in 7days. Got my wife to straighten bike up off stand while i looked at leak. Petrol over her toes was interesting



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mossproof


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If it only happens over night, just turn off the fuel

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MikeBarnacle


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Carb leaking petrol?
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so today i seen to have a petrol/carb leak issue.... I'm not sure why this is doing it but any one know??? 

Anyone know now why this is doing it and secondly what I need to do to stop it before I start taking bits off and making it worse!!!

i haven't been in there to do anything with the carb so bit confused as to why this is happening



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TTRfan


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RE: Carb/petrol leaking????
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Is it only coming out the overflow Mike?

If so then it sounds like the float needle isn't doing its job which means its worn/damaged/stuck cry



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MikeBarnacle


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Yeah only out of that part when it's coming from. Easy fix??? Hate removing the carb!

Will take it off tomorrow night and see if it's just stuck, hope so!

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TTRfan


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If the carb hasn't been apart for a long time then best get a carb float bowl gasket lined up from Steve as it is a safe bet that the old one will be flattened and leak on re-assembly!

After a TTR has been stood up for a while with the petrol switched off, it is not uncommon for the float to stick in the down position. Usually a sharp tap on the carb body with the non-pointy end of a screwdriver frees it off wink

Brian



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Ammity


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leaking carb
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my carb is leaking from the bottom right-hand side (if you're looking at it from the gear shifter side). Do ttr's use a little paper gasket that I should replace?



-- Edited by Ammity on Friday 19th of May 2017 08:44:37 AM

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mossproof


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The float bowl uses a special rubber seal:

totallyttrs.com/epages/699105d9-e4cc-4b32-b236-84e72cd67f84.sf/en_GB/



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ttr steve


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If it is from the bottom, then the likely culprits are these

https://totallyttrs.com/epages/699105d9-e4cc-4b32-b236-84e72cd67f84.sf/en_GB/?ObjectID=1718227

And these

https://totallyttrs.com/epages/699105d9-e4cc-4b32-b236-84e72cd67f84.sf/en_GB/?ObjectPath=/Shops/699105d9-e4cc-4b32-b236-84e72cd67f84/Products/TTR-0043

Steve



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Ammity


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is the diaphragm accessed from the bottom of the carb behind the plate with the two small screws?

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mossproof


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If you type "carb issues" into the search function on here, you will get a wealth of carb info with pics.

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ttr steve


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Yep

Here is a diagram for you

2004 carb.png

 

No 39 and the two No 36, be careful not to lose the spring!



-- Edited by ttr steve on Saturday 20th of May 2017 02:22:34 PM

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kitkat


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Carb Leaking
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Bike runs fine but if leave bike with fuel tap open then petrol starts collecting on bottom of cark and drips down left side (probably due to angle on side stand).  Cant see visually where the leak starts other than not from the tank hose.  Anyone else had this?  Dripping enough for fumes to be noticeable in the garage.  Turn fuel tap off and drips stop (eventually) Thanks Dave



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Cubber


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Carb leaking petrol?
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Kitkat,

Take a look at the earlier posts in this thread. I am sure your answer is in there wink

There are that many oportunities for petrol to leak that you really need to give more information of Where, When, How much, etc. confuse

Martyn



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katana


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Float needle is most likely worn or stuck. Float level is unlikely to change. Try tapping the float bowl with a metal object. If stuck open, it might close. Won't clean itself though.



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kitkat


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Bike runs fine but if leave bike with fuel tap open then petrol starts collecting on bottom of carb and drips down left side (probably due to angle on side stand).  Can't see visually where the leak starts other than not from the tank hose.  Anyone else had this?  Dripping enough for fumes to be noticeable in the garage.  Turn fuel tap off and drips stop (eventually)

Thanks Dave



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ttr steve


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RE: Carb Leaking
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Hi Dave

Carb Diaphragm by the sounds of it.

Steve



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kitkat


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Thanks Steve.  That sounds like a straightforward job?  A bit paranoid about taking a carb to bits and it not working afterwards!

Dave



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TTRfan


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Carb leaking petrol?
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Hi Dave

Lots of information to help you here http://ttr250.com/Carb/TTR250_carburettor_strip_and_rebuild_guide.htm

There are also a couple of video tutorials showing how to remove and replace the carb if you haven't done it before - see http://ttr250.activeboard.com/t63816667/removing-and-replacing-the-ttr250-carb-video-tutorials/

If the carb hasn't been off for a long time then it's worth going over it properly whilst it's off. Steve does a good kit with all the gaskets and O rings here - http://totallyttrs.com/epages/699105d9-e4cc-4b32-b236-84e72cd67f84.sf/en_GB/?ObjectPath=/Shops/699105d9-e4cc-4b32-b236-84e72cd67f84/Products/TTR-0767

Brian

PS You may have noticed that I have merged all the carb leak threads - hope that isn't too confusing but it's best to have all the relevant info in one place.



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kitkat


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Hi Brian,

Many thanks for the links.  Will order up the bits and get it sorted now

Dave



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