I can't see how a "pin" could break, I've seen the crankshaft break in two (V8 engines), but never a wrist pin. Since you say you can move the magneto and the small gear independently., I'm assuming that is what you mean, (crankshaft journal) where the the rod rides. The top of the rod rides in a bearing which is over the wrist pin, in the piston. Has to be a defect in manufacturing.Has anyone ever broken the big end pin, I did. Not sure how but after a loud snap, clank, click. tink, tink. The jug and piston were gouged badly 1/4" deep, Now i can move the magneto and the small gear independently.
Yep, sheared right in half. Motors been running strong for about a year and half. All the bearings seem fine, no grinding sounds and they spin freely, I can't see how it's even possible to break there, Everything else should have broken first. Don't know I'll post pics as soon as I get my gear tool back.I'm assuming that is what you mean, (crankshaft journal) where the the rod rides.
A lot of people refer to it as a crank pin.I can't see how a "pin" could break, I've seen the crankshaft break in two (V8 engines), but never a wrist pin. Since you say you can move the magneto and the small gear independently., I'm assuming that is what you mean, (crankshaft journal) where the the rod rides. The top of the rod rides in a bearing which is over the wrist pin, in the piston. Has to be a defect in manufacturing.
I balanced my crank. It's pertty easy. The problem is finding a crank without too much runout.I wanna say Gasbike.net. It was a true grubee GT-5. It's been running great for over year and a half, at least 2000 miles. Rain, snow it is my car literally. Has to be a casting flaw like Al said. There just is not enough power created by these motors to break things like that. OH well... So about this crank balancing thing Who's got the best info on home balancing?