This thread may live somewhere on the site, but I've been unable to find it.  I apologize if it is, but if not, I could really use some help.  

I bought a 2007 Suzuki S40 last summer that's been partially bobbed out.  It recently started smoking out of the exhaust when I start it up.  (This began just after an oil and spark plug change. I used Suzuki's recommended oil 10w-40)  When I start the bike, it smoked for about 2 minutes and then cleared up.  It's a bluish white smoke, smells like it's burning oil, and there's lots of it.  Someone told me to try a heavier oil to see if that helps.  I changed the oil yesterday and it actually seems to be smoking even more.  Now it smokes for a about 4-5 minutes before clearing up.  The bike seems to be running well, but I'm concerned about causing damage to the engine.

Two of the mechanics I talked to seemed to think the seals were bad/ going bad.  One recommended trying some ATF in with the oil, another recommended adding some "smoke treatment" to the oil.  Any thoughts or suggestions on this?   Both told me that if they have to tear into the engine it could be $1500!  I just bought the bike for $2,900 so I'd obviously like to avoid that...

Thanks in advance!  

Mileage?
what muffler do you have?
Is it consuming a lot of oil?

The best answer is
Change the petcock. Eliminate a problem that can create a myriad of symptoms,, And, its just a given its Gonna crap out if it hasnt.

How are you checking oil level?
IF theres more tomorrow than there is today and you checked it after it had drained down, then yea,, good chance theres gas in it,,
OIl doesnt lite very easy, but gasoline does.. You put some drained out oil in a more tubular than bowl shaped container, you force whatever gas is in it into a smaller surface area. Id expect gas to float on oil if it doesnt just mix in,, Ive never tried adding gas to a bowl of oil to see if it just blends in or if it will create 2 layers,I also dont know if it will seperate if its been stirred. One things sure, if it wont make 2 layers it wont seperate.

Anyway, one of those lighters with a long end on it so YOU arent in danger OR if youre blessed with a good enough nose, you could smell gas in the oil.,.

A coupla quarts of oil is cheap, especially when you compare that to losing an engine. Gas cut oil doesnt lube near as well,,
If I found gas, Id swap the filter, too,

when you fill the oil is the bike level to read the site glass not on the side stand?

thumperclone wrote on 06/05/14 at 14:47:21:


The bike has to be upright, not on the kickstand. It's a pain in the buttocks  . If you fill it to half in the sight glass on the kickstand you're WAY overfilled.

Trailwood wrote on 06/05/14 at 19:05:07:


WHen you changed the oil did you stand the bike upright to drain the old oil? If not you didn't get it all out.

raydawg wrote on 06/05/14 at 20:17:33:

the gas washes the oil off the cylinder and it gets scored up.

Faulty float could cause gas in oil, but how would a faulty petcock do that? The gas has to go through carb first. Blue smoke, like he said, valve stems seem more plausible.