Sell the 86 motor and the cr motor and get an 87-92  motor. They have power valves and are a lot better than the 85-86 motors in my opinion. Or get a zilla motor and drop that in it !!!!!👍

A zilla motor will not be a cheap swap but all the guys I have talked to love the end product ... There is guys in here that can help source either a 250 or 500 motor and all the right parts so it functions properly ... I if you do a 250 try to get the 87 cylinder they are supposed to make the best power from what Iv been told ... You could also snag a anti-vibe steering stem and fasst bars to help eliminate the bad vibes your getting ... Post some pics of this rig Iv never heard of this hybrid before

The 87 250 had a larger reed with I believe six bolts.  Preferred by sand duners. They have more horsepower but lacks a bit in torque.  The later models I believe use a 5 bolts reed and creates more torque. Better suited for trails or MX.  I may be wrong about it but that's what I remember reading in a different thread.

The 87 had 5 bolts for the reeds. 1988-1992 had 6 bolt reeds.