Ok i just ended up getting a 82 yamaha 400cc 4-stroke engine that came out of a yamaha maxim 400 (xs400j). I won't know for sure if its an 82 or not till it arrives but it eiter has 38HP (SOHC) or 46HP (DOHC).

I have 3 donor frames availible, a 300ex, 86 LT250R, and a 87 LT250R.... Other posibilities are welcome though.

So far i was thinking the 300ex would be the best choice for these reasons:

the 400 twin doesn't weigh that much more than the stock 300 engine. I can ditch the battery, some wiring, starter and other un-used parts to offset the weight gain. And they are both air cooled so there is no weight gain due to cooling systems. Should be a sub 400lb bike with very agile handling on the trails?

**This is not going to be a dunes bike, i want to use it for trail riding and Xcountry**

Any suggestions or comments would be helpful, thanks

 

I think the EX would be your best choice. It probably has a little more space to work with to put in that motor without having to hack up the frame. However, because I hate to see Yammie engines in Honda frames(or any mismatched motor/chassis combo) I would look for an old Warrior chassis, but thats just purely my opinion,a lthough it would probably fit a little nicer into the frame since it is a litle bigger quad.

 

86 LT250R, the bike only weighed 293lbs!! light *** frame.

 

I would go with one of the LT250 The 300ex has a short wheel base so it will be wheelie happy with that much power