Jump to content

78 xs400 leaking petcock


socalyamaha
This post is 6189 days old and we'd rather you create a new post instead of adding to this one. You can't reply in this post.

Recommended Posts

my petcock was leaking,

so rebuilt i rebuilt it. all new gaskets and vacume

still leaking

on and res settings.

Link to comment
Share on other sites

Do you want an ad-free experience? Join today and help support the Yamaha Owners Club.
  • Moderator

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?

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

  • Moderator

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.

Link to comment
Share on other sites

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.

????

Link to comment
Share on other sites

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?

Link to comment
Share on other sites

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:

Link to comment
Share on other sites

  • Moderator

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.

Link to comment
Share on other sites

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?

Link to comment
Share on other sites

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

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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?

Link to comment
Share on other sites

  • Who's Online (See full list)

    • There are no registered users currently online
  • Recently Browsing

    • No registered users viewing this page.
×
×
  • Create New...