bad crank seals?

[Eddie]

ok, i rebuilt the oil pump and checked all lines, i put si-7 2-stroke oil in the oil tank. I got the bike running and the far left and center cylinder (if sitting on the bike) smokes more than the right one, even at idle. I drained the antifreeze, and it looked ok, i put new points, but not condensors, and new spark plugs. I took the bike out for a ride to see if it would stop, I took the bike up to 90mph and left a smoke screen like hell! i then brought it home to check, the smoke at idle is not that bad, and it seems to only smoke from the left cyclinder? but not the right one, even at speed the left smokes more than the right, it runs good and the oil seems good but i have not really ran it enough to see though. I checked the spark plugs after the ride and the right and center ones are kinda wet (oily) but the left one is way lean, no oil at all? why? i even checked the tube in the cylnder that squirts the oil and its fine. I read that if two of the seals are bad it could cause the left cylinder to be lean or something? i thought if the seals were bad it would run shitty ? any ideas? im afraid of burning a hole in the left piston because it is so lean, no oil at all? and i know the oil pump works and the lines. How do your plugs look? do they all apear to look the same or do you guys have the same problem i do?

[Eddie]

also i had cleaned the sris check valves, for got to say that .....

[pearljam724]

I bought a 750 at the end of the summer. It did the same exact thing within a week of owning it. After I changed the plugs, put proper fluids in it, removed the baffles, bled the pump of air and ran it consistently for a few weeks. It never smoked out of one particular pipe. More than the others again. Perhaps yours has a leaking check valve or crankseal. Piston rings could contribute to this behavior also. Several things. My problem went away. After the bike was ridden. Which, I know the PO let it sit a lot.

[Eddie]

Thanks for the reply, I had cleaned the baffles also, how does your plugs look?, two of mine are wet, oily, and the third one is dry and lean, I was thinking maybe carbs but if the one carb was lean then the plug would be more oil right? I'm afraid it's a crank seal but I have no way of doing a leak down test. I had rebuilt the carbs already , the bike started doing this about two weeks after I bought it, and in about three years I have put maybe 800 miles on it! Everything the guy told me that he did was bullshit, I think it sat for years and he got it started but never cleaned or drained anything which caused problems.....

[pearljam724]

Both of mine run great and after every couple hundred miles. The plugs are a black mixture of dry and wet look. Not soaked, but a sticky black oil residue. Did you synch the carbs ? According to your description of the plugs it sounds like a lean carb. Too dry or white colored plug, means leaner. Wet is rich. Too rich, can cause more smoke in one particular cylinder. But, if the bike starts, idles and runs fairly. The carbs aren't causing the additional smoke. I think you have a lean carb.

[Eddie]

The bike starts and idles fine , but even at idle it has visible smoke from one side and not the other. Thanks for the help, I hope it's just the one carb, but I don't think so. either I have two cylinders that are rich and one thatis lean or one perfect cylinder and two that are to rich? Never thought I'd say that, wow....that sounded pretty stupid,,,,,there's nobody around here that I know of that has a buffalo that I can compare to, I will keep running it until it dies and I have to rebuild it i guess., I'm thinking crank seals but I will take a look at the carbs again.

[pearljam724]

Where do you set the pump adjustment at ? Factory recommended, lower or higher ? If the crankseals are bad. Excessive oil and smoke would come out of your breather and pipes. One pipe would not smoke, while the other two cylinders did. Does the smoke on all pipes cease after the bike is warmed up?
I mentioned the carbs as a reference to your plug.

[Eddie]

the oil adjustmebt is set to factory, it smokes even after warm, not alot from the right pipe but from the left and center pipes, its not alot at idle but when you give it throttle it smokes ill try to take a video to post.. my compression was 110/105/105 from right to left..

[pearljam724]

You will get a lot of different opinions in regard to the pump adjustment. But, the factory suggested pump adjustment was recommended at a time when the oils were of a much poorer quality, different thickness and different chemical properties. With modern oils you can adjust the pump much lowerer. You can attest to this by adjusting on either setting and watch how much the bike smokes after its been warmed up. With the factory setting and modern oil the bike will smoke entirely too much. Even after the bike is warm. It will also spew out a lot of oil from the exhaust. When a 2 stroke of any kind smokes entirely too much after operating temperature. It means the oil mixture is too high. Therefore it smokes more than it should and the motor has to get rid of the excess oil. I mentioned this because you stated the bike smokes excessively at operating temperature. Try adjusting the pump. Something else to think about. When everything is right. These bikes smoke excessively at start to operating temperature. But hardly smoke at all. If everything is set properly and mechanical sound at operating temperature.