marc,it has a iso block,by B H Hanson (metal) and teflon gaskets (no pressure tap). It may be the seals,as I haven't checked them out yet,(not really sure how to do that?) I can't seem to get the flat metal plate (behind the recoil starter off. They must have used red loctite on the screws. Ron

Cut some slots in the screw heads with a Dremel and cutoff disc and remove the screws with a good flat screwdriver. Works every time.

If the seals or base gasket leaks, you will see visual signs (oil)...

I don't remember anyone mentioning it but with the 257 carb a good starting place for the needles is 2 1/8 out on the low side (one next to the cylinder) and 1 1/8 on the high side. Just turn them in gently until they contact bottom then back them out. I use a screwdriver with a adjustable clip for reference..Adjustment will be a little fat but should be good to start with......

Thanks for the information guys! Ron

Thanks,for all the information,guys! I tore the motor down,and found the rear crank seal was leaking. It also had rust in the rear crank bearing. I replaced,all bolts with a CC Racing stainless bolt set,new copper,cylinder base gasket, both bearings,seals,piston ring,wrist pin,and bearing. It runs great now!:dance2: I had a little trouble getting the bearings in (used the oven method) and it took 450 degrees to get them to seat,but it worked,I also noticed that the seals produce some drag on the crankshaft. (I guess they are sealed now)? Thanks again for all the help. (PS>) the carb setting were spot on L=2 1/8 H= 1 1/8. Ron

Excellent! Glad you found the problem! :drinks: