I know why the oil was gassy, why was it so dirty?

[matt_gs450]

Hi All,

Last spring, after a short ride on my 450T, gas flooded one or both cylinders. I suspect it was debris holding open the petcock and allowing gas through the carb and into the cylinder.

After draining and changing the gas, and verifying the petcock was OK, the problem stopped. However, gas had been allowed into the engine and was mixed with the oil. Regrettably I rode around probably 40 miles with the engine in this condition, not realizing it might cause other problems. After each ride, a few drops of oil would leak out from the seal around the clutch lever.

On Saturday, after the bike had sat for a few months (winter) I started up the bike again, and it coughed out black smoke for a few minutes. It ran with a lot of hesitation and low power. I drained the oil and removed the filter. I was not surprised that the oil smelled of gas, but I was surprised that the oil was really dirty. I had changed the oil shortly before the gas leak occurred last Spring.

Anyway, after the oil change, the bike is running great again, and there is no oil leak after a ride.

What I'm wondering is:
1. will the gas in the oil episode create any additional problems I should look for?
2. why did "fresh" oil get so sludgy so fast? I have only ridden the bike maybe 100 miles between the previous oil change and this one.

Thanks for any help,

-Matt

[Big T]

Matt,

I can't follow your story.

Did you change the oil last year after you discovered the gas leak?

And that oil is sludgy and smells of gas?

[rapidray]

The gas has more detergents than the oil & you riding it that 40 miles or so with the gas/oil mixture CLEANED a lot of the garbage out of the inside of your motor. This is NOT a good way to clean the motor so don't do it again. If the crankcase ever gets filled with gas like that again, change the oil BEFORE you ride it! Ray.

[matt_gs450]

Hi T. Sorry, my storytelling skills suck on Monday. Here is a timeline:

Jan 2008 - rebuild carbs for this bike which hasn't run in years
Jan 2008 - change oil
Jan - June 2008: rode about 80 or so miles on the bike
June 2008 - gas leaks into oil
June 2008 - August 2008: rode another 40 or so miles
Aug 2008 - Feb 2009: bike sits
Feb 2009: change oil again. old oil from Jan 2008 is really dirty.

Thanks,
Matt

[matt_gs450]

Thanks Ray. I learned that riding with the gas in the oil was bad when I read the owner's manual last week. I was kicking myself after reading that. I put a lot of work into the bike up to this point and I have my fingers crossed that I didn't do too much damage. Perhaps it was even "good" for the engine but that remains to be seen.

I hadn't considered that the gasoline acted as a cleaning solvent inside of the engine. If that's the case, there was a lot of junk built up in there. I assume the buildup is dried oil which is suspending some solid particles and is stuck to the upper parts of the engine (?).

-Matt

[gearman]

If it ain't rattling your lucky. Mine was ridden less miles under the same conditions (except it was hot out) and now has a bearing knocking.

[Big T]

Thanks for the clarification. So,

#1. Possibly, but if it runs okay now you've probably avoided them. Very bad things,like bearing or pistion seizure, can result from gas thinning the oil.

#2. What Ray said. The inside of your motor should be nice and clean now

[Steve]

Even without the gas, you can not get ALL the oil out of the engine when you change the oil. It is rather surprising how quickly the new oil will be dirtied by the old oil, and look positively BLACK, but still be good, fresh oil.

.

[Zook]

If gas got into your oil from a stuck petcock you still have some work to do...on the carbs. The gas got into the oil via the float needle, which did not shut off the fuel flow.

[matt_gs450]

Rats... Just tried a ride. The bike had no power at all. I could barely get it to start up from a dead stop without dying. I rode around for 30 minutes to make sure it was warm.

When I got back, I took out the spark plugs to have a look. They were both black around the threads and the electrodes were dark gray. According to the manual that's carbon fouling and is caused by a rich fuel mixture.

I hope that's it. I'm going to clean them and try again tomorrow.

[matt_gs450]

As a conclusion, the rich mixture was a result of a bad petcock. The gas was basically pouring down the vacuum tube and bypassing the carb, going straight into the cylinder. It's probably what also allowed the crankcase to flood with gasoline. Although, when I had the carbs off I did notice some gunk around the float needle screen.

Just to be safe, I added an inline fuel filter. The bike runs great and I'm looking forward to the warm weather!

-Matt