By
hisun junk
As I tried to do a conversion with the Yamaha 660 motor, I realized the 660 was never fuel injected so it would not work for the fuel injected hisun motor swap. But the good thing is the hisun 750 motor is a clone of the 660 Yamaha but with the components for the fuel injection (cam/crank position sensor). So that left me with a new rebuilt Yamaha 660 and still a broke 750 hisun motor. I took apart 750 think the timing chain had broke from all that I've heard about these motors. The chain was not broke, but just off cam and crank gears! The chain tensioner was at fault! I've ordered Yamaha 660 replacement parts, chain, two exhaust valves (which got bent when chain came off while motor was spinning) and seals. The piston has 2 little nicks where it had hit valves but no damage otherwise. The head is being redone at the machine shop and I'll be putting it back together in the next couple of weeks. Also I finally tracked down a Service Manual with all the info on the 550/750 Challenger.
By boydog40
By SouthernGypsy
By Frank in MI
By hisun junk
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