Crankcase seal-need enlightment please

[Rustytinhorn]

85 Atc250r
I'm afraid I'm sucking oil and I've been told there are two possible seals, the RIGHT crancase seal?? and another seal just oustide the crankcase??? The LEFT crancase seal creates lean conditions when gone bad, correct?
A shop here wants $360 just to split the case in labor alone. I can't afford that.
I have been looking at the micro fish, (brain just went blank on name and spelling of the diagram charts), but I am having a hard time telling exactly what seal(s) I need and how to access them the best. Does it require splitting the case?
If I could be brought up to speed on this I would greatly appreciatte it.

Thanks

[Billy Golightly]

The crank seals do not require splitting the cases. It makes it easier to press them in straight and reduce the likely hood of ruining them or not getting a complete seal but it can be done without splitting the cases. To replace the right seal, you need to remove the right side engine case, and the clutch assembly if I remember right. 2 hour job tops, from start to finish. Make SURE you do a leak down test before you put everything back together though. Hell do a leakdown test before you take it apart and make sure the crank seal is where its coming from.

[Dirtcrasher]

I'll second that above reply...

[Rustytinhorn]

Thanks guys,
It will probably take me longer to build a leak tester than to just replace the seals, but I need one anyway, so I guess now is a good time to make one. lol
:lol:

[rally4x4racer]

how are you going to build the leak tester? when he said that I was trying to picture in my head how to do it.... no luck

[Billy Golightly]

Made a new thread for ya (And anyone else) with all the details: http://www.3wheelerworldforums.com/showthread.php?t=71487

[3Razors]

A tip to getting old seals out is to drill a small hole in the seal then use a sheet metal screw and insert in the hole. Use a pair of pliars and pull on the screw which will pull the seal out.

[Rustytinhorn]

I'm almost dead positive my crank seal is bad. I have spent the last 6 months tuning my carb in a very meticulous manner. One size, one movement, one clip position at a time. I go so low on my jets I starve the bike of gas, and the plug still comes out oily. For those that are wondering I've tried yamalube and now I'm running Klots Supertechniplate 32:1 at 5280ft and I puff blue smoke like the devil. I'm tearin my water pump apart tomorrow to make sure my bike isn't overheating and causing the problem. After that the only thing left that I havent gone through that could be causing a problem would be the crank seals.

Sorry for the explenation, now for my question.
I know I'm not sucking air. So that elimates that seal from the picture.
If I am sitting on the seat facing forward toward the front tire like I was riding, which leg would the crank seal be under that would cause the bike to suck tranny oil if it went bad? Would the oil-sucking seal be on the right hand side of the bike or the left hand side? I'm having a hard time getting a definate answer.
Thanks a bunch.

BTW, thanks for all the tips

[Rustytinhorn]

how are you going to build the leak tester? when he said that I was trying to picture in my head how to do it.... no luck

I'm goin to make it as simple and inexpensive as possible.

I'm going to remove the intake boot, and bolt on a flat metal plate in its place. This way I can use the existing gasket. I'm gonna drill out two holes in the plate and put a valve stem and core in each hole. One to push air into to pressurize everything, and the second one to use my low pressure gauge on.
Then on the exhaust side I will just remove the flang and bolt a flat plate on there to seal it off.

[Billy Golightly]

I'm almost dead positive my crank seal is bad. I have spent the last 6 months tuning my carb in a very meticulous manner. One size, one movement, one clip position at a time. I go so low on my jets I starve the bike of gas, and the plug still comes out oily. For those that are wondering I've tried yamalube and now I'm running Klots Supertechniplate 32:1 at 5280ft and I puff blue smoke like the devil. I'm tearin my water pump apart tomorrow to make sure my bike isn't overheating and causing the problem. After that the only thing left that I havent gone through that could be causing a problem would be the crank seals.

Sorry for the explenation, now for my question.
I know I'm not sucking air. So that elimates that seal from the picture.
If I am sitting on the seat facing forward toward the front tire like I was riding, which leg would the crank seal be under that would cause the bike to suck tranny oil if it went bad? Would the oil-sucking seal be on the right hand side of the bike or the left hand side? I'm having a hard time getting a definate answer.
Thanks a bunch.

BTW, thanks for all the tips



Sitting on the machine, right side crank seal is the one suppose to be keeping the oil out.

[Rustytinhorn]

Thanks Billy.
Went through the cooling system today. Checks out in good condition. Slowly getting this thing running piece-by-piece. Looking foward to my dunes trip in a couple of weeks. I'm gonna try to make my leak down tester this week and check on that seal.

[Rex Karz]

It is important to do a leak down test just like it is important to do a compression test. Otherwise you're just "shotgunning" it, guessing at different things.