Topic: Has anyone else had problems with blow by?

[Dirty Steve]

Just want to know who else out there has/had a problem with gas mixing with the oil and how you fixed it.
Thanks...

[ekpent]

Turn off the petcock when not riding, make sure petcock is not leaking internally when off, make sure fuel level is correct in the bowls and make sure your float needles and seats are in good condition and clean. All that should help.
   If you think its getting past the rings then that is an issue with them. Does it smoke or burn oil ? Compression and leak down test may be insightful.

[madmtnmotors]

Turn off the petcock when not riding, make sure petcock is not leaking internally when off, make sure fuel level is correct in the bowls and make sure your float needles and seats are in good condition and clean. All that should help.

+1

If the fuel valve is left on, and one or more float needles are not sealing properly, it can allow excess fuel to overflow into the engine. This can be further exaggerated if the overflow tube on the carb is plugged or restricted. This condition is often accompanied by fuel in the air cleaner as well.

[Vinhead1957]

I wouldn't call it blow by its flooding!   You got gas coming out of everywhere!  Float valve and or other related carb faults.   You just rinsed the inside of your engine. Do not run it with contaminated oil.   Change oil and filter and look into the carbs

[fmctm1sw]

I had a Suzuki that drained the tank into the crankcase.  That was an unpleasant surprise when I changed the oil...

[mrfish2]

I had blow-by in one of my cylinders, resulting in a lot of gas in the oil. Ended up having to put new rings on the pistons.

[flybox1]

Overflow tubes are there to prevent this. . .

[madmtnmotors]

Overflow tubes are there to prevent this. . .

As long as they are not clogged or pinched. Little mud dawbers or other debris plugging one or more overflows?

[Dirty Steve]

Thanks all for your input:
It did smoke a little at first (white) but no longer.
I will look into the overflow tubes again. I blew them out previously, but have never seen them actually drain.
Used clear tubing to determine fuel level but haven't yet taken the bowls off to actually compare.
Replaced float valve assemblies and one of the floats. Have checked float level numerous times.
Compression is between 140 and 145 psi.
Petcock does not leak.
No fuel in air filter.
Thinking about replacing rings.
Thanks!

[ekpent]

How many miles have you put on the bike so far ? Before you start down the road of an expensive engine  tear down which on this forum looks to be about a 50% success rate make sure you have the easy stuff covered first. Got a picture of this machine you can share so we can evaluate the overall condition.

[Dirty Steve]

Well, I was shocked to discover that I've put 350 miles on it. That's over the last year with probably 10 oil changes because of the above-mentioned issue.

[Dirty Steve]

I don't understand how the overflow tubes are supposed to drain excess fuel from the bowls when there's so much vacuum pulling fuel into the engine in the first place.

[flybox1]

Your jets can't pull more fuel than they are designed to.

[ekpent]

What do the spark plugs look like and does the bike smoke. If the rings are shot or froze in the grooves there should be some tell tale signs there probably.