Can anyone in hamilton Id the motor for me then? I thought originally it was a 701 but on closer inspection i think its a 650, deffinately seems to have a 650 head but the pistons seem rather large
Check the casting numbers and measure the pistons (701= 81mm pistons). Heads: 6M6 = 650 61x = 701 62t = 701 64U = 701 64x = 760 Cylinders: 6M6 = 650 61X = 701 62t = 701 or 760 64x = 760 Cases: 6m6 = 650 61x = 701 singlecarb 62t = 701/760 twincarb
Sweet that cleared it up, seems like its pretty much a box of bits really. The bottom end is 6M6, pistons have 650 stamped into the top of them but are 84mm across, the cylinder is 62T but has an 84mm bore (pistons and bore are fucked anyway) The head has no casting marks but has "Yamaha 650 29" stamped around the sparkplug hole. The bottom end, head and intake setup appear to be in ok condition, just throw some new bearings at it, find a new cylinder and piston combo and go for gold I think.
oh, with the cases the bottom half are the same thru out, and all have 6m6, is the the top half that differs, the cast mark is usually just above the starter motor hole. that head sounds like an aftermarket west-coast brand head , does it have a 'W' logo on it? , the '29' means 29cc domes (which when used with a head gasket equates to about 35cc) if the pistons are 84mm thats 760cc
Nope, has Yamaha cast into it and the serial number MWVEW2HD stamped into it. the top half of the crank case has 6m6 on it above the starter hole, the inlet manifold has j700l and a few other things.
