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78 xs400 leaking petcock


socalyamaha
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my petcock was leaking,

so rebuilt i rebuilt it. all new gaskets and vacume

still leaking

on and res settings.

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my petcock was leaking,

so rebuilt i rebuilt it. all new gaskets and vacume

still leaking

on and res settings.

Is it through the lever?

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Is it through the lever?

no, the fuel line.

i set it to on and it leaks.

i set it to res and it leaks.

half way between them both and it leaks.

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no, the fuel line.

i set it to on and it leaks.

i set it to res and it leaks.

half way between them both and it leaks.

I'm assuming that you mean it has free fuel flow rather than an external leak?

is the lever hard to turn?, it should do as i have rebuilt mine and it is stiff, you need to make sure everything is in the right order off a parts or workshop manual (you can see an online version at motogrid) ensuring the rubber is the right way round and covering the right holes etc.

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I'm assuming that you mean it has free fuel flow rather than an external leak?

is the lever hard to turn?, it should do as i have rebuilt mine and it is stiff, you need to make sure everything is in the right order off a parts or workshop manual (you can see an online version at motogrid) ensuring the rubber is the right way round and covering the right holes etc.

yes, free fuel flow.

the bottom gasket can only go in one way. done.

the round four holed gasket behind the lever is the the same both sides. done.

the vacume gasket, little hole in the membrane lined up with the little hole in the plastic plate.

spring is against the back of the cover. o ring facing through "tunnel" to lever side.

done.

????

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yes, free fuel flow.

the bottom gasket can only go in one way. done.

the round four holed gasket behind the lever is the the same both sides. done.

the vacume gasket, little hole in the membrane lined up with the little hole in the plastic plate.

spring is against the back of the cover. o ring facing through "tunnel" to lever side.

done.

????

I am having a similar problem: http://www.yamahaclub.com/forums/index.php...amp;#entry47881

Have you had any luck?

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I am having a similar problem: http://www.yamahaclub.com/forums/index.php...amp;#entry47881

Have you had any luck?

not yet.

the bike only has 5900 miles on it and i rebuilt the petcock, there should not be a problem. :angry:

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not yet.

the bike only has 5900 miles on it and i rebuilt the petcock, there should not be a problem. :angry:

just buy a new one and have done, its not having it!, so bite the bullet. :(

if you were in the uk i would have looked at it for you.

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just buy a new one and have done, its not having it!, so bite the bullet. :(

if you were in the uk i would have looked at it for you.

I talked to my mechanic and he doesn't think its the petcock (i looked at it and it looked ok - not that I know exactly what I am looking for).

He suggested tapping the floatbowls to see if anything is stuck in there - would that cause it to free flow out the air intake?

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I talked to my mechanic and he doesn't think its the petcock (i looked at it and it looked ok - not that I know exactly what I am looking for).

He suggested tapping the floatbowls to see if anything is stuck in there - would that cause it to free flow out the air intake?

When you wrote to say that your petcock was leaking, why did you not write and tell us that fuel was leaking out of the carbs. That is a different story to a petcock leak. Fuel is leaking out of the carbs (how many?) because the float is not sealing off the inlet That is a seperate problem to a leaking petcock

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When you wrote to say that your petcock was leaking, why did you not write and tell us that fuel was leaking out of the carbs. That is a different story to a petcock leak. Fuel is leaking out of the carbs (how many?) because the float is not sealing off the inlet That is a seperate problem to a leaking petcock

my problem is the vacume doesn't work the way it should.

no fuel should be coming down the fuel line to the carbs when the engine isn't running.

you should check your float bowls.

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When you wrote to say that your petcock was leaking, why did you not write and tell us that fuel was leaking out of the carbs. That is a different story to a petcock leak. Fuel is leaking out of the carbs (how many?) because the float is not sealing off the inlet That is a seperate problem to a leaking petcock

I had in the thread I linked too. I assumed it was petcock at first because I am a nub.

I knocked around the floatbowls and it runs now. Should it clear itself or will I have to empty the bowls?

edit: throttle is jerky sometimes / unresponsive - is the debris just floating in and out of the jets / whatever?

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