[Walt Fricke]

The only seals you really have to replace are the little O rings which go on the case through bolts. Some, if not all, of these get squished on installation. I've saved a few which looked more or less OK in case some day I don't have enough new ones on hand (I bought a package of a hundred or so a few years ago, but I've been into my motors a couple of times since).

Everyone likes to replace the seals at both ends of the crank. Both can be replaced without opening up the motor, but the flywheel seal calls for pulling the motor and flywheel, so not easy. The #8 bearing seal can be replaced without pulliing the motor, so there is less risk taking a chance that the old one, if not leaking, will do fine.

The oil pump and oil cooler seals do not need replacing unless they are hard and brittle. I've reused these several times on one or the other of my motors. They are captured, so they aren't going anywhere. I've not seen them lose their length, so on reinstall they will be compressed again.

Bearings are a tough one - I have several bags of "good used" ones, but can never find it in my heart or wallet not to put in new ones. I've got a new motor which may need to be disassembled entirely with only some dyno time on it, and I'd be very inclined to leave those alone. I just took apart a 100+ hour race motor. Bearings were so good I marked each as to where it went, just in case. I've been thinking to contact the coating places to see if they will coat a used bearing. Then I bought new bearings. One more bag of old bearings in the collection.

Maybe I ought to start replaciing chain ramps. I've busted a few old ones when prying them off - the clips on the one pin seem to get brittle. Broke an old one putting it on as well. Never had one fail in the motor (but see the post from a guy who found one of the pins holding the chain housing ramp in place in his crank sump). Amazing.