Gasoline in oil?

[swright442]

Hi, newb here....changed oil earlier and much to my dismay I found gasoline in the oil! Could a new petcock cure this or am I looking at a more serious problem? Thanks in advance! Scott

[Rod_Knockin]

a new petcock could do it but only if your needle and seats don't seal properly. is the bike hard to start? Flooded. I would worry about the cylinder filling up and bending something on start up.

[swright442]

The bike can be hard to start if it sits for a week or so. It may flood a little on start up but not terribly. This is a 76 750f that sat for about five years before I got a hold of it. Just trying to get the bugs worked out.

[Rod_Knockin]

I say needles and seats. might as well clean out the carbs wile your in there.

[gonebiking-2]

There are two scenarios to this problem. One is that fuel is leaking from the carb/s into the cylinder/s and then bypassing the rings and running into the sump. However - if this was the case and if it was flooding , the fuel would be running out of the rubber overflow pipes and onto the ground. So then you would smell fuel all the time. Second case scenario - someone may have accidentally poured fuel into the sump, although I would question why anyone would be so stupid to do that, but thats the nature of the human beast - we can and tend to do stupid things from time to time.

The other scenario - and this currently applies to my bike,  is that oil is running down the valve guides, past the valve stem oil seals and fouling up the plugs. Then when it does eventually start, it blows out a cloud of blue smoke  until it clears. Mine only does this if it stands for a week or more. Overnight , it starts first time, hence the head is coming off to be rebuilt

[swright442]

Interesting. Don't think anyone has poured gas into the sump. The gas got into the oil while the bike sat for almost two weeks. Gas will leak through the overflow tubes if I don't shut off the petcock. So, I'm thinking that while the bike sat, gas leaked through the petcock and due to the angle of the bike, followed the path of least resistance directly into one or more cylinders, probably #1. Not really sure just yet but I did put new oil and filter in and rode it about 125 miles today and everything is fine at the moment. I currently have the fuel line disconnected from the petcock and a length of tubing running off the petcock to a Mason jar. I'll let that sit over night and see if I get any leakage.

[gonebiking-2]

I agree with you regarding the line of least resistance - number one cylinder will invariably cop all the problems. So it might be a faulty petcock. New ones are still available, but will be interested to see what the results are with a line running into the Mason jar.

[swright442]

Nothing overnight but a few drops-still watching...

[gonebiking-2]

Its one of those frustrating problems by the sound of it. Bit like having constant toothache, then you go to the dentist and he cant find anything wrong. So I guess its a waiting game for the time being. Having ridden 125 miles and everything appears to be in order , I guess one can assume that its a faulty petcock that has a mind of its own. Its frustrating to say the least, but it looks like a waiting game to see how much fuel collects in the jar over the next fortnight

[Rod_Knockin]

i leave my fuel shutoff pet cock on all the time. My bike doesn't leak because the float needle and seat are doing their job and are in good shape. if your bike sits and leaks fuel its the needle is worn out and seeps fuel past it causing flooding. Put the bike on the canter stand and put the mason jar under the overflow hoses and leave the fuel on.

[gonebiking-2]

Since day one I have never turned the petcock off  ( although on two oacsions in the early days I did, and wonderd why it ran out of fuel on a busy road. Once the fuel came through, she was up and on the run again, and to this day have always left it on. I know its valve stem oil seals as once I can get her started, she blows blue smoke out of all four cylinder until such time as the smoke gradually disappears. Then she can go all day and stop for an hour and start up and runs perfectly. So I know as far as my 750 is concened its not  leaking petcock, as on the rare times I have had to take the fuel tank off and the petcock is shut in the off position, there is no fuel leaking on the work bench. And as its standing in the garage there is no fuel leaking through the needles a these carbs were completely overhauled earlier this year.

[Rod_Knockin]

gone biking,
what is the issue your looking for advice on? I'm a bit confused now as this thread was started by swright442 and was about gasoline in his oil. Maybe start another thread to keep from confusing the issues.

swright442,
one thing I forgot to mention is when you replace the needles to check the floats to make sure they float and don't have liquid inside them from leaking. Its rare for a float to go bad but it can happen. Check and double check the float level setting when re assembling.

[gonebiking-2]

I dont have an issue with my bike nor was I asking for advice. My CB750KZ is running like  it should do. I was helping with the other guys problem with fuel in his oil.

[Rod_Knockin]

ok, it just confused me in the wording. Sorry.
this bit sounded  like you had an issue too.
quote:
"So I know as far as my 750 is concened its not  leaking petcock, as on the rare times I have had to take the fuel tank off and the petcock is shut in the off position, there is no fuel leaking on the work bench. And as its standing in the garage there is no fuel leaking through the needles a these carbs were completely overhauled earlier this year."

 I would help (if I could) if you did have an issue.
probably just my interpretation.

[gonebiking-2]

No mate. But thanks for the offer. Usually when I have had to take the tank off, its been to do with the throttle cables adjustment, or other silly reasons - such as getting a stubbing spark plug out .

But thanks for your concern. It seems you and I are the ones that are helping everyone else out there judging by the number of replies we seem to give to our fellow Honda bikers ! keep up the good work as I pick up a thing or two ftom your posts.