gas in oil again!

[Guest]

Recently had problem with gas in my oil on 850, so bought a new petcock after testing old one and it leaked when set to "on or "res". Finally got to ride a little yesterday, was planning to today. But checked oil level in window and was above entire window! Carbs. were properly rebuilt couple of years ago but didn't replace needle valves or seats. Looks like I will be now. Can't think of anything else that would cause this. I just did a top end rebuild this winter with new valve seals, lapped valves, lightly honed bores, and of course all new oem gaskets. I have not had a lot of luck with motorcycles lately. Sorry just had to vent. terrylee

[tkent02]

Recently had problem with gas in my oil on 850, so bought a new petcock after testing old one and it leaked when set to "on or "res". Finally got to ride a little yesterday, was planning to today. But checked oil level in window and was above entire window! Carbs. were properly rebuilt couple of years ago but didn't replace needle valves or seats. Looks like I will be now. Can't think of anything else that would cause this. I just did a top end rebuild this winter with new valve seals, lapped valves, lightly honed bores, and of course all new oem gaskets. I have not had a lot of luck with motorcycles lately. Sorry just had to vent. terrylee

Carbs can't do it if the petcock isn't leaking too. You sure you didn't leave it on Prime?

If the petcock were working properly the carburetors would have no gas to leak.

Where did you buy the new petcock? Confirm you bought a vacuum petcock?

[Nessism]

It's easy to over fill the oil, and oil expands when hot so you need to check it cold while the bike is on the centerstand. Just an off hand way of saying it may not be the carbs.

[bonanzadave]

Carbs were properly rebuilt couple of years ago but didn't replace needle valves or seats.

Sort of a contradiction...but even the tightest valves and seats will leak if the petcock is left on PRI.

[eil]

Does your oil smell like gas? Easy to check, just undo the fill cap in the clutch cover and have a whiff. If you have gas in the oil and a functioning olfactory system, you will know it.

Did you know that there is a procedure for checking the oil level in the sight glass beyond glancing at it? Consult your factory service manual, but it is roughly this:

1) put bike on centerstand, on level ground
2) start engine, let it run for a few seconds
3) stop engine
4) wait 60 seconds
5) check oil level in sight glass, should be between L and F.

The upshot of this is that if the oil level is correct, it will always appear to be too full if the engine was last shut off more than 1 minute ago.

[terrylee]

I wish I had left it on prime, no such luck. It is aftermarket petcock, same one I know others on here have bought, have one on 450 for couple of years with no problems. It is vacuum operated. Drained oil after discovering gas in oil last time and then installed new petcock, let oil drain for over an hour, including filter. Measured oil carefully and only put in 3.8 qts. manual calls for. Will take tank off tomorrow and let it set with fuel hose into a small can and check it next day and see if any gas has leaked out with it set to "on" Guess it is possible I could have gotten a bad new one. terrylee

[tkent02]

Bad new petcocks happen. So do mistakes with the oil level. If you just went by the manual number and didn't check it in the window after filling it the oil could have been way too high all along.

[JTGS850GL]

Could be dirt in the tank causing the new petcock to leak or you simply overfilled the oil. As stated above, check the oil for a strong gas smell. You can double check the petcock by disconnecting the fuel line and run a new line into a cup to catch any leaking fuel. Go to sleep... In the morning, check the cup for gas. If no gas, then the petcock is good.

[terrylee]

I did check oil level, what I do is not put in the last 1/2 qt. and start bike for about a minute or so. Shut it off and let it set for 15-20 mins., then check window, then top off so it's between low and full, being close to full mark. Went out last night and hooked up spare fuel line on petcock and put it and vacuum hose into small can, checked it this morning and not a drop of gas in it. Will change oil and check for gas and then fill oil being extra careful on amount, let it run, let it set and make sure it's where it suppose to be on window. terrylee

[tkent02]

What you can do to get familiar with a your bike, is notice the oil level in the window right after an oil change, when it's measured correctly as above, then when it's stone cold on the centerstand see how far the level changes, how far do you have to lean the bike over to get the oil down to the level in the window? Look again when it's completely hot shutting it off for a minute, it usually doesn't change much but at least you know. That way you can check it all the time, even during a short stop on a long ride, if it's not in the right place you'll know right away.. Also get familiar with where the oil is if it's on the side stand and just pull the bike up to vertical for a second.

I just took apart a 750 engine last week that was run low on oil until it quit, there was still at least a quart of black nasty oil in the crankcase. One piston came off the wrist pin, the timing chain broke, black burnt aluminum dust all over everything, it's a mess.

[terrylee]

Drained oil, no smell of gas. Measured oil that came out minus little that was inside filter (after letting it drain), amount seems right on. Maybe just as you guys said will read a little high after setting along while. Going to let it drain for a hour or so just to be sure it's all out. Then fill it minus maybe a 1/4 qt., run for a while then check level in window. Guess I'm just paranoid after last petcock was leaking gas into oil; over night test proved it was leaking. Thanks for all the advise, I feel a lot better about the issue now. terrylee