Lower End Rebuild

[kjh]

So I made a Rookie Mistake.  Did Frame up build with a motor that I bought.  While I had the motor out I figured I might as well rebuild the top end, however I didn't do a leak down test and after the first few rides I discovered that oil is pouring out of the bearing behind the sprocket, oil is blowing out the pipes, it has a rich condition in the mid range, plugs are saturated with oil....but hey it starts on the first kick!   The bike has a 7mil twister crank, all the shift mods, straight cut gears with lock up.   I have never had to do a lower end rebuild. What needs to be replaced, checked or upgraded? Can I do the rebuild from the bottom or do I need to disassemble the top end agaiin?  Should I buy the shift drum with bearing from Trinity racing?  I ride dunes only with emphasis on hill shooting.

[Jereme6655]

1) A leakdown test would not tell you that you have a bad seal in the transmission area as it only pressurizes the crank area.

2) Oil blowing out the pipes at the cylinders is a common issue.....alot of the time its just the o-ring in the pipe flange that needs replacing. If its alot of oil it could be the ratio or type of oil that your using that is also causing issues.

3) Since you already need a new seal.....get a seal kit for the lower end and replace them all.  Also you should look into getting a billet waterpump as stock plastic ones tend to fail and melt motors. 

4) You should.....i say SHOULD be able to split the cases without taking off the top end....ive never had to do it for that....but i have done it for swapping tranny shafts.  Your clutch arm seal is gonna be a little harder with the top end on.  Also just pay real close attention when slipping the pistons back in the jugs.

 

5) No. No...and FUCK NO........you should NEVER buy anything from Trinity.  It would be like voluntarily putting your dick in a rabid dogs mouth.....no matter what happens.....your not going to admit it after you did it.  Trinity has a bad name around here for their motor setups.....so everyone avoids them like the clap.

 

Jereme