Gas in the oil

OK reading this forum I got paranoid about my bad gas mileage (about 35 mpg), so I checked the oil fill cap and I have a slight smell of gas in the oil. Took it one step further, I still have the oil I changed out a couple of weeks ago and I smell gas in it(did not notice any smell when I changed it though).

I am positive my petcock does not leak - I have had the tank off several times. I am not positive that gas is not going into vacuum line but I will test that.

I just had the valve cover off to check the clearance and did not smell gas then.

So what am I looking at? Stuck float? Engine appears to be running great. No issues at idle, no hesitations.

I assume it is not a good idea to ride the bike till I figure this out and flush the oil?

Thanks

 

Either a stuck float or float level and yes, NOT a good idea to ride it until you figure it out.

 

Thanks Michael. I plan to pull them tonight. Will clean and check them out. I'm hoping it's that simple. If none of the seals are bad I intend to follow Rick's cleaning instructions.

Then flush the oil and hopefully ride.

If I just clean the carbs and don't disassemble the butterfly linkages do I need to sync? I can bench sync easy enough but I need to get or build the YICS tool to do a sync.

 

I would just do a float level check before pulling them completely apart. If you only have to adjust a level, no resync would be needed in my humble opinion.

 

OK I understand how to check float level using a tube (I fear my drains may be seized but that's a different issue - have not tried them yet.) How would you set the float level then? I thought the height had to be adjusted by bending the tang?

 

You are correct. You will need to pull the bowl for any carb that is out of spec, bend the tang, replace the bowl, and recheck. I know, a PAIN IN THE BUTT, but that's how it's done.

Also, do not check with gas, use some blue windshield washer fluid instead in an old gas can with a fitting and fuel line running to the carbs.

 

instead of useing washer fluid you can put a few drops of food coloring in your fuel...makes the fuel easy to see and you dont have to flush the washer fluid out when youre done

 

Cool thanks guys.

I got it now Micheal I thought you were suggesting a level check before removal from the bike - I need to learn to read.

I was only planning on cleaning the bowls as I suspect a stuck float. Bike is running great just bad gas mileage which lead to the discovery of the gas in the oil. Planning to do the whole cleaning this winter.

I have spent more time tuning and stuff than riding so far, but the results should be worth it. I had 2 very lean cylinders which I now have tuned real close. That made a big difference in the way the bike was running.

Thanks again for all the help! Without this forum I would have kept riding it, (blissfully ignorant as it ran fairly well) with the cylinders lean and gas in the oil until it blew up!

 

OK pulled the carbs and trace of gas was in the #4 airbox boot. After disassembling the bowls #4 and #3 float height were low (drain screws prestriped by a thoughtful previous carb mech).

Cleaned a bunch of stuff out of the float needle valve seats and screens, the fuel rails and the bowls. Cleaned the jets. I reset the heights - screws will wait for the rebuild

After I put the carbs together I hooked them to the gas tank off of the bike and turned it to prime. Bowls filled and no leakage after sitting several minutes. So I hope it is fixed. I think only time will tell. I changed the oil and filter and ran as suggested. then changed oil and filter again. Ran it for a bit.

I can't smell anything after all the carb cleaning. My son checked and it appeared the smell is gone. I'll ride it tomorrow and check for gas. My petcock is fine so it was only when running (I assume idling).

 

Re: Gas in the oil - need more help

OK I'm back - gas back in the oil. Petcock is fine, not pulling gas from vacuum tube.

Pulled and drained the carbs. Blow into gas tube and air flows. Turn carb over and no air passes so needles do seal.

Pistons pass the clunk test. (which I assume has nothing to do with gas in oil but I tested them anyway.)

My drain screws are stuck and pre-stripped as I mentioned above. I set the float heights by measuring off the carb body.

So the main question is what can cause the gas in the oil other than float level adjustment?

I have Cylinder #4 valves too tight by .001 inch (shims in hand yesterday thanks to Chacal) can that contribute to the problem?

How does gas get in the oil when running based on float level? I assume my engine would bog down if that much gas is going into cylinders but it runs great!

I am going to extract and replace the drain screws so I can check the level correctly. Can't ride it until I resolve this issue.

Thanks for any help!!


Update 7/18 - found a thread on dry setting floats - but need some clarification on it to be sure.

http://www.xjbikes.com/Forums/viewtopic/t=9998.html

Also got 1 of my drains loose so I can set the float height and then set the others to match at least! If I understand the float instructions I found ALL my floats are WAY too high.

 

Bump edited my post from last night with more info - thanks

 

Polock ( i think) put out a tip to dress the needle and seat:

Sharpen a wood golf tee to get rid of the paint, use the golf tee in the "seat" to polish it.
Gently polish the "needle" with 1,500 - 2,000 grit.

Or just get new parts, of course.

Set your oil level up so there's just a tiny bubble left, so if you are still getting gas in your oil, the bubble will disappear.

 

I have the sane problem with the the 1st left hand carb.

Cleaned and replaced floats and jet.

When I use the kick stand, the angle the bike sits to the left, gas would leak into the cylinder.

Overnight the cylinder would fill up so much I couldn't even turn the motor over!

Removed spark plug and turned over motor and gas would shoot out!

I drained the oil to find at least one litre of gas mixed with it.

It sure cleaned the motor out good as I drove it with the gas in the oil, as I recleaned the carbs 10 times not knowing this was happening.

At first I just closed the gas valve, but the gas left it the bowl would leak into the cylinder.

The bike would spit and backfire until the gas in the cylinder would burn off.

So now I use the center stand to park the bike and no more leakage (I also turn off the gas valve off a few blocks before going home to lower the gas level in the carb too)

This may solve your problem?


eye_share

 

Thanks for the info. I suspect something similar but if the float heights are correct what you describe should not happen. I should clarify I never had issues like yours - Bike starts/runs fine but gets gas in oil. Like I said I suspect the same scenario - sitting on the kick.

Last night I tore into the carbs again with a much better understanding of how to measure/set the floats. My drains are stripped (parts on the way) so I am measuring height. Long story short all 4 were at about 10 mm - spec is 17.5 mm

I was able to free one drain so I used that bowl (moving it from carb to carb) to verify the levels and the are right on. I also verifyed that at 10 mm the level was WAY too high. Then I tore most of the carbs down (did not mess with splitting ) and cleaned. Just put everything back together and was going to run it that way after flushing oil to see if I solved it.

As things go on these bikes I also did the shims and a cover bolt broke, so I have to get extractors and since I can't run it now I will do the drains and wait on the parts that should be in on Tuesday or Wednesday.

I'll update this thread late next week to see if it looks resolved.

 

If you have a stuck needle it would still do this. I think that was his point. How do they look in the carbs? Maybe something to look at.

 

I checked the needles I think mine was the floats being way off(7mm) so the fuel level was over the gasket level. I suspect someone changed the floats and never set them. I have only owned a month. Thanks for the help...

 

Looks like my gas in oil issue is solved, along with an exhaust leak that developed. I left a bubble in the oil window as suggested and no issues. I have also been keeping it on the center stand during long parking period like work and home over night. I thinks my needles are fine but it's easy enough to use the stand. I cleaned the carbs but this winter I will tear them down completely and replace the needles in the process as I did see slight wear.

 

I'm happy for you!! Well done!

...but now, wish me luck, i'm another victim of gas in the oil....ASAP i'll check the level of the fuel and...yeah, you know