Dec 9, 2007
30
0
I have been having issues with crank seals. I bought a new set and put them in and coated a thin layer of grease inside the lip of the seal so it wouldnt be a dry fit around the crank. I get around 3 hours of riding time before my exhaust spits out a butt load of white smoke. The spring pops out and the inner lip is torn. Burnin the gear oil thru the motor. Was wondering if you guys put any sort of yamabond type gasket maker around the outer edge of the seals and inside the case? Ive had this problem twice. Is the best way to install the seals before you glue both cases together or afterwards when the cranks in place??

Thanks
 

2strokerfun

Member
May 19, 2006
1,500
1
Don't know what the "best" way is, but I normally install them in the cases before I install crank. On some bikes, where the clutch side bearing is lubricated by the trans oil, you have to install the seal first (because it's inside of where the bearing sits). But you have a problem. What type of bike are you working on? Sometimes I've had to pull the crank a couple of times and reinsert it to get the seal to seat on the crank properly. You might try warming up the seal a bit before installing the crank. If you are sure you have the seal seated on the crank properly, you might have a problem with the crank, ie. crank is out of round, not true or has some other defect causing it to beat the inside lip of the seal. Or maybe some foreign material in your trans/clutch area getting caught on the seal and tearing it (that's a long shot in my opinion). Is there perhaps some play in your bearing you are not aware of??
 
Dec 9, 2007
30
0
I will try warming them up a bit. I am working on a 06 YZ 250. I inspected the crank and it appears to be in good shape. Its a brand new hot rod crank that has less than 10 hours on it. over half of the lip was torn off and the spring was barely kept in. I did buy a complete oil and seal kit off ebay so Im sort of turned onto the fact that I bought a cheap kit. I ordered OEM yamaha seals. So hopefully this time I wil get more time on the bike. Thanks for the reply man
 
Dec 9, 2007
30
0
May have found what was causing the seals to go bad, one of the shift forks was excessively worn down and my 3rd and 5th gear was worn. Seal may have gotten faulty by metal peices from shift forks. Anyway have 3 new shift forks, 3rd and 5th gear on order. Hoping for the best.
 
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