Burning Oil in rear cylinder - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 18 (permalink) Old 04-18-2011, 04:17 PM Thread Starter
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Question Burning Oil in rear cylinder HELP

I bought this bike last September as a possible bike for my brother or girlfriend.

I've done quite a bit to this bike and it was running perfectly until Friday. I rode up to get an ice cream and it didn't want to stay running. Finally I got it to stay running with some dificulty but oil smoke was pouring out of the LEFT pipe and I see oil under the rear cylinder.

Do I have a bad gasket? What other problems should I look for?

-Brian, F6Rider from Columbus, OH

Last edited by F6Rider; 04-20-2011 at 11:55 AM.
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post #2 of 18 (permalink) Old 05-07-2011, 05:36 PM Thread Starter
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Cool

Okay, decided to replace rear cylinder's head gasket. Upon removing the head, I see burnt oil on piston itself. Not something I didn't expect, however, I see NO signs of a failure to the gasket. Do I possibly have another issue?

If anyone has experienced this or any similar issues, please reply.

I'm having a LOT of fun with this project though. It's been raining a lot here, and at least I'm working on my #2 bike.
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post #3 of 18 (permalink) Old 05-07-2011, 06:55 PM
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how are your valve seats any leakage? since you have it open might as well get some grinding compound do it this way also change for valvestem seals.

http://www.youtube.com/watch?v=BzhLe4jngPw


anytime your on the bike hard it will eat oil .................a quart a month is acceptable......
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post #4 of 18 (permalink) Old 05-07-2011, 10:00 PM
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Mine smokes when I start it now after sitting a few hours
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post #5 of 18 (permalink) Old 05-08-2011, 11:01 AM
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Aside from the hints above, there is the possibility of a broken ring(s). Do you see any significant scratches on the cylinder wall? Also check the automatic valve lash and make sure it isn't frozen from ingesting some recent junk. I disagree with anyone saying using a quart a month is normal. I ride daily (38 miles both ways), my 88 has 64K on it, and I use zero oil between changes. Good oil, good filter, good maintenance, good engine!
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post #6 of 18 (permalink) Old 05-08-2011, 11:40 AM Thread Starter
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I'd definately have to agree with George!

"I disagree with anyone saying using a quart a month is normal."

I'll be checking these suggestions later today.

Thanks guys!

...All you see from me are Dust & Taillights...
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post #7 of 18 (permalink) Old 05-08-2011, 02:44 PM Thread Starter
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Okay, no scratches on cylinder walls...

Valve Lash isn't frozen...

Valve seats are good too...



Any other suggestions?

...All you see from me are Dust & Taillights...
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post #8 of 18 (permalink) Old 05-08-2011, 03:51 PM
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yep could be rings too

as far as 1 quart of oil being used..........didn't say it was "norm" but acceptable especially if your running it hard any shop will tell you the same thing keep the engine around 7 to 8 grand for a while, you'll burn oil the Vulcan engine wasn't meant to putt putt around like a Hardly at 4k all the time


if you try to bring it into the shop and say my bike is eating a quart of oil every month to 3000 miles they will ask you and? That's acceptable.....

but yeah if you putt around never really let the engine open up then you may not burn that much or very little at all....... I on average have added half a quart in the past 3000 miles its around the same for the Triumph as well.
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post #9 of 18 (permalink) Old 05-08-2011, 07:22 PM
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Okay, we're off topic from what F6Rider was asking. But just for the H of it, I don't putt putt anywhere, anytime. I rarely shift 1-2 below 7500, consistently hit the on ramp in third at about 8K and when I'm pissin off an HD guy I'll rev to 9500 3rd and 4th. Still have 64K on my motor and zero/nada/squat oil use between 4000 mile changes. If ANY of my bikes burned a quart/month, I'd at least hone and re-ring if the cylinders miked to within .002 of factory and over bore if it was beyond. But, that's me. And the last time I asked a shop mechanic anything I was riding a f'ing moped and packing lunch to school in a paper bag. Try this on for size, my c5 'Vette has 8 cyclinders and about 80 times the Hp of the VN750, and it also doesn't burn a quart/month...never met a 'Vette owner that did burn oil unless the engine was fubar...so why would a 60Hp twin suck that much oil unless it was hurtin?

Now, back to F6Rider, another question comes to mind...you said it was smokin out the exhaust, found oil on the piston etc...did you notice if there was a large amount of oil in either or both of the air cleaners?? If you did, then it's a clear sign of excess blowby, and that's a ring problem without question whether there is cylinder scarring or not.

Also, even though you didn't see an "obvious" sign of gasket failure, it takes less than .005 inch seal loss in the VN750 to cause oil migration.

The big question is, how many times do you want to pull that motor from the frame, and how much can you spend right now? The problem is that you yanked the mill before taking a CR. That would tell a lot. Because if the CR was low, but the valves are solid (turn the head upside down and pour mineral spirits in the intake and exhaust ports, if it runs out then the valves are fubar) then it has to be the rings. Or the gasket. Or the stem seals. Point is, once the pumper is outta da frame, replace all that is within financial grasp. Or, Rinse. Lather Repeat. Personally, I hate the repeat option.
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post #10 of 18 (permalink) Old 05-08-2011, 07:54 PM
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F6Rider, just reread your posts from earlier. IF there is no significant oil in the air cleaners, and IF the valves are okay, and IF the auto lash is Okay...then I'd still bet on a crisped head gasket. I'll go out on a limb here and bet more than one pair of tools has wrenched on your motor previously. Inattention to head torque readings can be problematic and lead to unexpected joy for no apparent reason. I'd slap a new gasket on, and, against the Kaw service manual advice, I'd use either the spray on Permatex CopperCoat or the Yamaha head sealant on both sides of the gasket an hour before reassembly...not on the cyl or head....because if in a previous life someone did not use anti-freeze in the motor, there could be some minor corrosion that eyeballs can't see on the mating surfaces.

I'll be checking back and wishing you luck.
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