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.

Well I finally got back to work on my junk hisun Challenger 750 UTV. I purchased what I thought and asked for a fuel injected 660 Yamaha motor out of a rhino or grizzly. The salvage place said they had one and would have it rebuilt for me. (the only way they sell their motors) The problem is hisun cloned the 660 Yamaha increased the bore & stroke to 102mm x 90mm from 100mm x 84mm. Identical motors, but the Yamaha was never fuel injected I found out when I went to install it. The place I purchased the motor said it was, I requested that it be a fuel injected motor and again the salesman had said it was. The 660 Yamaha was produced from '02-'08 but only with a carburetor. So no crank position sensor for fuel injection to work. So now I've tore apart the hisun junk motor and found that the cam/timing chain had come off the gears. It either stretched or the tensioner failed. The piston hit both exhaust valves and bent them. Dropped the head of at the machine shop yesterday for new valves and clean it up having them check the three intake valves plus all the spring pressures. The replacement vales and springs will be Yamaha as needed. The cam/timing and tensioner will be replaced with Yamaha parts as well. The piston and bore looks good with only two little nicks where valves hit. The Motorcycle Doctor in Florida is a hisun junk dealer and has parts for sale on eBay or direct at 573-346-6867 or motorcycledoctor.com. I would suggest taking the time and use Yamaha parts when you can. As you can see from pictures below the hisun has a different intake port compared to the Yamaha 660. That's what got me started into checking out the 660 motor not being fuel injected. I get the head back in a 1.5 weeks, timing chain and tensioner is ordered, then I'll put it all back together and do another post. Also if anyone needs a rebuilt Yamaha 660 for a rhino or grizzly '02-'08 let me know $2,750.00 shipping included.

I’ve done a lot of research on this swap and a good buddy of mine is an awesome ATV/UTV mechanic which gave me a lot of good info. hisun 750 (735cc) 38.22 HP Yamaha 700 (686cc) 50HP That in its self is worth it!

Joe, Motor is suppose to be done and shipped out in November. I’m going with after market clutches and will post when I start the exchange and post pictures as well. Michael

I talked with the rep for the company that I purchased mine one 2018 and he went to the top dogs at cub and they said no warranty on the hisun junk and they quit carrying them. It will take a class action lawsuit in order to get cub to do anything! They motor is a clone of the 700 Yamaha, so I’m having one rebuilt and will post on the exchange when I get it to install.

Joe, Which ATV/UTV rebuild company did you talk with? Rhinos are getting hard to find. Which Yamaha motor are you looking at? The 660 is the one they used for cloning the 750 in my challenger. Thanks, Michael

I'm in the process of getting the Yamaha motor which is the motor they cloned for the 750 in my challenger.

I have a 2018 cub cadet challenger 750 with a broke chinese hisun motor and I know that I'm not alone! Almost all the places that were selling them in Colorado don't anymore due to the return for repairs on the clutches and broken timing chains! Don't have yours fixed because it will happen again! They just replace the broken parts with more junk chinese parts! I talked with a UTV mechanic that has replaced one person's clutch 4 times! I have people contacting cub cadet about these problems and also looking into complete motor replacement from hisun junk to a Japanese motor in which the chinese cloned their junk from.