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Post Info TOPIC: Carb pipe hole


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Carb pipe hole
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I noticed that I had a little petrol come out of this hole When I turned the fuel on. I had only just cleaned the carb it stopped after a few secs and hasn't done it since. as you sit on the bike this hole is on the right hand side of the carb on the bottom of the float bowl. I think it's for a pipe I didn't see a pipe on it when I pulled the carb.. Anyone know if this is for a pipe and if so does anyone know the diameter or have any I can have pretty please? 

 

 

image.jpg

 

 



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Overflow. Float must of been briefly stuck

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Pete. South Somerset, England.



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Yes i agree with Pete, you need to run a length of pipe down behind the engine from it, could be difficult to route.

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checked the fowlers parts thing but they are out of stock...

Brian do you have one!

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This Yamaha diagram shows that you have pipe 12 missing

Image.jpg

If Fowlers can't supply the Yamaha pipe then just get a suitably bored poly tube and bung it on.

Martyn



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East Budleigh. Devon



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Cheers mate. That's a good diagram you have there actually. better check it ain't missing anything else. I did notice that when I pulled the choke out it didn't really engage that well when pulled right out you kind of have to find a sweet spot..i unscrewed it to check it and noticed that there is a little clip in there same as whats on a carb needle. does that do anything?

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Take your pick - this is the exploded diagram of a carburettor

carb.jpg

and this is the description of the numbered parts

carb desc.jpg

Martyn



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East Budleigh. Devon



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TTRHead wrote:

checked the fowlers parts thing but they are out of stock...

Brian do you have one!


Only just seen your post - will have a look tomorrow. The likelihood is that I have one.

The pipe can be tricky to fit to the carb unless you have tiny hands or are triple jointed!

Just for info, here is a pick of the drain/breather pipes that run up to the airbox.

Over the years, crud falls into the pipes and can affect the operation of the one-way valves (indicated by purple arrows) so best to do the suck/blow test to make sure they are OK. Don't try sticking anything up them if they don't work coz that will damage them. Soak and clean them as best you can without getting physical wink

Carb pipesa.jpg

 



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Is the clip on the choke plunger to stop it retracting?

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Pete. South Somerset, England.



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This is what the choke looks like outside the carb:

Choke_assembly 2.jpg



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Cheers Brian

 

Out of interest what is this bit for?

Choke_assembly 2.jpg

 



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It's a C clip that acts as a stop for the spring that fits inside the sprung end of the choke that goes into the carb body.

Not noticed before but there are two further grooves that it could sit on but not sure they are deep enough for the clip. But why would it be adjustable confuse



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As the spring gets weaker?..

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Pete. South Somerset, England.



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Brian does the check valve serve a purpose? Mine seems to be missing

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peteBLUEttr wrote:

As the spring gets weaker?..


 Don't think so as it takes tension off the spring as you move the circlip towards the knob confuse



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One way valves on the pipes are needed if you go through rivers/fords not to drown the carb

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Pete. South Somerset, England.



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TTRHead wrote:

Brian does the check valve serve a purpose? Mine seems to be missing


 Do you mean the one-way valves in my photo?  If so, they allow petrol or any other fluid that gets into the lines out without letting water back in. Lots of dirt bikes don't have them and trail open pipes down low that can suck up water into the carb or just stop the bike working. The early WR400s suffered particularly with this.



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An not those there is another sticky about cleaning the carb which shows a brass part on the float bowl called the check valve

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I know on my old bike the spring used to go funny at times and the choke knob wouldn't stay out. Had to tension it up



-- Edited by peteBLUEttr on Friday 26th of June 2015 12:47:55 AM

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Pete. South Somerset, England.



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I was talking about this part when I said "check valve" I thought that's what it was called!!!

image.jpg

 

 

 

 

 

 



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It's called a valve check seat. Probably no biggie that mine doesn't have it.. Looks just like some kind of locating pin for the float bowl...

Think I'd rather save me £19

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The check valve is a one-way valve that sits below the accelerator pump pipe that sprays petrol into the carb mouth. Mr Yamaha doesn't put unnecessary parts in his bikes so my guess is that the accelerator pump won't operate properly with out it.

Got an overflow pipe here!

Brian



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