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Post by flyereddie on Apr 9, 2007 6:53:52 GMT -5
Hi Guys
I have just taken my tank off to check the tappets and the tap keeps letting the fuel flow, I know these are supposed to turn off without any vac but mine keeps flowing. My manual is a bit vague on the subject and doesn't show the valve that shuts the fuel off, Is it repairable can i just put in a new part or do I have to replace the complete tap?
thanks
Mark
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Post by colinjay on Apr 9, 2007 17:38:03 GMT -5
Hi,
The first question is what position do you have the tap in? If the tap is in the "On" or "Reserve" positions, then it should not flow fuel unless a vacuum is present at the vacuum hose. If the tap is in the "Prime" position them the tap will flow fuel continiously. There is no "OFF" position on this type of tap.
If the tap is leaking fuel while in the "On" or " Reserve" positions then you will probably find that the rubber sealing disc inside the tap has gone hard and does not seal anymore. I don't think the disc is listed in the SR parts manual, but you can get the disc for other model Yanahas and you can generally find one that will fit. I have replaced this disc on my SR but I can't remember what model the part came from. If you ask a good Yamaha mechanic or parts guy they will know what part will fit.
CJ
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Post by brokenicarus on Apr 10, 2007 8:58:27 GMT -5
Hey Mark,
I rebuilt my petcock with one of these kits, I got it off ebay for 25 bucks us.
it said it would fit these bikes, if you can track down any of their rubber petcock sealing disks you should be able to pick it up for less than $10.
XS360 C/D/2D 1976 - 1977
XS400 D 1977
SR500 E/F/2F/G/H? 1978 - 1981
XS650 E 1978
XS750 D/2D/E/F 1977 - 1979
XS1100 E/F/G/H 1978 - 1981
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Post by flyereddie on Apr 10, 2007 23:40:03 GMT -5
Thanks Guys
Now all i have to do is find a kit and ride around untill my tank is empty I had just filled it !
Thanks again
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Post by flyereddie on Jul 31, 2007 6:05:41 GMT -5
just thought id update this link. I replaced all the rubber bits in the tap and the diaphragm but it still would not turn off. It started off but as soon as the vacuum turned it on it would stay on. I left it this way for a while but it bugs me to have something beat me so last weekend i took it apart again , I thought it might be jammed on something but when i got it to pieces the vacuum was still holding it open even though i hadn't started the bike for a week. As soon as I broke the seal of the diaphragm the spring popped the valve shut. In the backing plate there is a small one way valve I suspect this is supposed to let air out quickly and slowly let air back in so the tap opens on the first kick and stays open for a short time even without any vacuum. Mine would let air out but not in. I started to remove the one way valve it is swaged in so I was knocking the punched tabs out but before I got it out i tried it again and I could suck air out and blow a little in so it was "leaking air" back in which I think is how it should work. I could not find any other way for air to get back into the chamber . Took it for a spin and all went well so Ill keep my eye on it and hope it keeps working
cheers
Mark
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Post by miker on Jul 31, 2007 14:07:43 GMT -5
Interesting... that valve is probably to bleed off any vacuum that might remain when you shut the engine off. If it won't let air in, that could well be your problem.
Obviously we don't want that valve to let TOO much air in, as that will go down the pipe and into the manifold leaning the mixture.
miker
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Post by flyereddie on Jul 31, 2007 18:59:23 GMT -5
Hi Miker
The valve is "inline" in the vaccume line so once evacuated no further air can bleed in , when the engine stops the air bleeds back in, I think the valve is susposed to be leaky , mine was a good seal !
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Post by miker on Aug 1, 2007 10:46:34 GMT -5
Ah, inline... makes it more clear. Thanks.
miker
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