Fuel in the oil XS2

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Hertfordshire (Letchworth) UK
Hello forum readers,

I have read most of the carb forum threads looking for some direction and experienced based advice.
My XS2 was running a little strange after a carb refurbish, diagnosis - incorrect float needle valves that I have corrected now. Now my concern is that fuel and oil mixed was sat in the sump for some months, static run only during that time, what damage might have occurred to seals etc during this time? Is it worth throwing in some sacrificial oil on the rebuild to flush through all the crank and engine seals then dump it before replacing with fresh oil for a second time or to replace the engines seals anyway to save problems further down the line. Or am I being over cautious?
I would dump the oil,add new run it for a short time and then dump it again. Any left over would evaporate with the heat.
Once put up for the winter it's best to NOT run the engine. Short periods of idling contaminates the oil. 10 minutes of idling won't warm the oil enough to boil these contaminates out. These contaminates create acids that can damage engine internals.
Pulling the battery and keeping it charged is a good idea.
Running not so much.
Even setting 6 months with out running won't hurt. Oil tends to leave a film on parts that stays there for long periods.
Some on here have picked up bikes setting for years without running. A tune up, fresh oil and gas and they run great.
The only way fuel can get into the oil is #1 you leave the petcock ON.
#2 the petcock leaks.
If your pet cock is working and you turn it OFF, fuel can't get in the oil.
A lot of people believe the float valve will prevent this, It won't. The float and float valve is a metering device. It controls the fuel level in the float bowl when the engine is running.
If it was a fuel shut off, why would the manufacturer waste the money to put on a petcock?
2nd what Leo said. In Minnesota once you put the bike away you do not start it. We have long cold winters. Unless it was completely full of gas I doubt you did any major harm. Just keep an eye on it next season.
I wouldn't worry much I've dumped a crank full of gas out of a bunch of old bikes threw in new oil and was off and running. Once the motor is hot any residual fuel hiding in nooks and crannies will quickly boil off. I do like to do that first change then do a fairly short run and do a second change on ANY "been sitting" bike, like maybe 500 miles? More about getting rid of any rust, varnish, oil water sludge, that sitting for years may have deposited in the engine.
Hi Griff,
don't sweat it. OK, enough fuel in the oil will wreck a plain bearing motor if it's run long enough but I doubt a roller and ball engine will even notice a minor fuel contamination on the brief runs you describe.
Consider the old Villiers 2-stroke engines, they ran just fine on a 20/1 petroil mix.
The worst mix you could get with the XS650 engine full right up with fuel atop the oil would be equal parts.
So the gas I discovered in my sump was due to a leaking petcock? I thought a sticking float might be the culprit.

Hi twin,
it takes a dual failure to put gas in the sump.
First, the petcock has to leak or be left on or gas won't get to the carb.
Second, the float &/or the float valve has to be stuck to overflow the carb and let gas leak into the engine.
Note that a good float/float valve will keep a bad or left turned on petcock from leaking gas into your engine but that scrupulously keeping the petcock turned off will only disguise a failed float/float valve.
Just a little story here, food for thought.

Every spring, customers would bring their bikes to the shop for after-winter-storage spring tuneup, usually because they weren't running right. Normal tuneups solved these, but a unique few would have additional problems, like fuel (lots of it) in the oil. These were the Honda CB450s. The owners inadvertently left the petcock(s) on, and fuel got into the engine. We found the carb float valves were ok, but how did the fuel get into the engine?

Very long story made very short: The CB450's carbs and inlets are tilted forward a bit. During the typical Texas varying warm/cold winters, fuel would evaporate from the fuel bowls, condense in the inlet tracts, drain into the engine. The float valves did their job properly, keeping the bowls filled, replenishing the evaporated fuel, and the cycle repeats. Over time, a couple quarts of gas would end up in the engine. This was mostly a CB450 thing, didn't see it on the others...
Thanks for the good info. I'm gonna charge the battery and get it firing. Then I can drop the carb bowls and see if the float is stuck, and if I'm getting fuel to the carbs. Hopefully it will start and run ok. I still need to flush the engine and get all the gas out. I'll fill with oil, run, and flush again after I determine all is well. Thanks again!