when you remount, remember that the goal is not to make the mounting bolts tight, but to make the motor tight - this means adding whatever amount of spacers that may be needed to get the motor to fit snugly in the frame before the bolts are ever tightened
I cant agree more here!!! This is SO important. I am a noob that learned the hard way. The comment also before about the engine case being soft is so true also.
What I do now when its engine mount time is this:
- First, make sure bike frame is secure, upright and level/close to final riding position etc(meaning if the wheels arent on it, just make sure the frame is not rotated way forward or back etc if that makes sense), best to have the front and rear wheels on bike and tight, I dont worry about getting the chain over the rear sprocket etc until after the engine is mounted perfect.
-Now find the sweet spot for the engine. Without any rubber or anything at all between the frame and engine (metal to metal) I lower it into the "V" trying my best to keep the frame tubes as perpendicular and flush as possible on either side. I want to gently shimmy it back and forth into place, NOT force it(this can cause frame stretch which is very, very bad!) Tap the engine a little on each side, rotate it, etc. try a few different angles and take your time. Every engine/frame combo "should" have a sweet spot, or at least a best position possible.
- After I have the engine perfectly wedged between the two frame tubes, making sure im fitting flush on both sides, hopefully have 0 or as little gaps as possible between frame and engine mounts. Its ok to have small gaps though if you cant avoid it. Now I JBWeld (2 part epoxy resin dries hard as metal) and literally fill in between the frame and engine mounts anywhere its not perfectly flush. This welds the engine in place.
This is all before I attach a single bolt or u clamp.
The next time I do this I want to use those awesome muffler u-clamps and fabricate stronger mounts like ive seen on some other bikes. Relying on the standard engine mounting brackets/bolts etc even if you do all of this perfect still can have issues/fracture/fail etc. I end up using no rubber/insulator at all except for a small thin layer with the u-brackets where they make contact with the frame to keep it from scratching it up.
Please share any other suggestions/tips.
First build/bike. "Funhog"