hi guys, need some help on a question. I have an 86 trx 250r motor on my leagers racing mx quad. im looking for another back-up engine, or bottom end for a spare. my question was " is a honda 250 r 3-wheeler engine the same?" " is the bottom end the same as an 86 trx 250 r on any year 3-wheelers" I was asking because a neighbor of a guy that works with me has one for sale at 250.00$ ! im not sure of the year yet of as now, but i have been told that it is in good shape. the seller is an old man who bought it new and does not know the retail marketing price of selling it used, if he was smart i am sure he would sell it for more!!! any help would greatly be appreciated!! i am mainly concerned with the bottom end, if it is the same i will throw an extra ct pro-x cyl on it, so i am not concerned with the top end being the same.
thank's a bunch guy's for any input you may be able to give me.
happy motoring, matt.

 

The 86 TRX and ATC engines will interchange with each other.
ERIC

 

The '85-'86 ATC engines are nearly identical to the '86-'89 engines. The differences are all internal. You can also bolt on any year cylinder to any year bottom end, as long as you use the correct piston for the rod in the engine. '85-'86 engines have a 5mm shorter rod than the late model TRX's; stroke is identical at 72mm, but rod length is different.

 

There are tons of things off the 3-wheeler that will fit right on the quads. Does the guy have the whole ATC? If so, you might see what he wants for it, cause I know the rear shock will fit, the swingarm, the carb, the motor, the axle and carrier, etc will all fit on the TRX. I am in the process of buying an ATC 250r for spare parts. I plan to sell the frame for whatever I can get and keep what will go on the TRX.

 

The shock will fit with some mods. The ATC shock is slightly wider on top and the hose that connects the canister to the shock is shorter than the TRX. Good luck selling the parts, I still have a bunch of mine. I'm thinking of trying E-bay.
ERIC

 

I agree about the 85-86 bottom ends working, and the shocks with a longer hose. But I think the '85 has different gearing. I have heard that the '85 has a taller 6th gear and might make a good TT bottom end.