Petcock and Carb valve seat issues

[bobiii84]

1980GS550L. Had issue of fuel leaking into oil. I can't reproduce a petcock leak with the tank off, but I think my petcock is working intermittenly. There SHOULD be overflows that let excess fuel go out but it's a slow leak. If I'm not mistaken the only reason fuel is still getting into the oil and not out the overflows is a leak in the valve/seats right? The previous owner to this bike had rebuilt the carbs at one point and said when he pulled out one of the old seats, it was pitted so he used emory cloth and put in a slightly more snug seat. I just found this out the other day :/ I would like your opinion on whether or not my conclusion seems reasonable (Well, not just mine) And what I can do about it. For now, I plan to drain the oil, AGAIN! Then put a fuel shut-off valve in the line under the petcock. When I am not running the bike I will shut it off. This will stop the petcock leak, and SHOULD keep any excess gas out of the carbs. I think it's bernoulli's principal or something like that. Let me know what you think, thanks!

 

[mike_of_bbg]

Have you checked the petcock vacuum line for signs of fuel? You can replace it with a clear line also and see if there is any fuel running in the line. That would dump fuel right through cylinder #2. Eliminate that possibility first.

OEM needle valves/seats are still available, though they are $30/carb. Could also be a leak around the o-rings around the seats; those are cheap.

 

[bobiii84]

I ran it today and couldn't see any fuel going through there, just for a couple minutes though. I tossed a cut-off in there that I'm going to use for a while and see if that works as a temporary "fix". I used a timing light on my ignition btw Mike, and now it doesn't appear to be smoking lol!