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Rocketman
06-11-2002, 01:53 PM
Are the 86 250r ATC and TRX motors the same?
And how about the later TRX motors, are they the same
as the ATC motor?
ATCRYDER
06-11-2002, 05:46 PM
they are not -exactly- the same. I would thing a trx would bolt right up to a atc and vise versa. The trx was jsut converted up a bit to handle the extra weight and wheel.
Dirtsquirt
06-11-2002, 11:22 PM
86-86 are the same save for the piston a small changes, nothing to affect compatability. Honda went to the long rod (+5mm) in '87 which requires 87-89 cases or a spacer plate.

They went to the long rod to help smooth out the power AND lessen the wear on the cylinder/piston walls. They also changed the pistons throughout the years.

Bottom line is that the short rod motors will produce more abrupt "peaky" power than thier stroked brothers. If you are just an average rider this won't matter much, only the most expirienced can tell the difference in delivery.


-Dirtsquirt
Rocketman
06-12-2002, 02:38 PM
DirtSquirt, are the heads the same?
Some time in the past the motor in mine blew up, and the head
as a bunch of pits and rough spots in it. I was thinking about polishing it out some, but may just replace it.
250rAL
06-12-2002, 07:03 PM
The motor was actually detuned slightly when it was first used in the 86 TRX. They used a thicker head gasket to lower the compression. An ATC gasket can be used on the TRX to get this back. Don't ask me why you would want LESS power for a heavier machine.
Rocketman
06-13-2002, 07:34 AM
Ok, but does anyone know if the heads are the same?
Dirtsquirt
06-13-2002, 08:41 AM
Yeah, for the most part I believe. They may have changed the bowl shape but as it was from a 85-8 ATC or 86-9 TRX it should fit.


-Dirtsquirt
Mr. Richard
06-13-2002, 09:24 AM
the water outlets were in different places on trx motors too..
200x_Basket
06-23-2002, 01:09 PM
so can i put a trx cylinder on my 85 bottom, or are the cylinders different too? the spacer plate allows the use of the long rod but can you use the stock rod and the later cylinders together??
Dirtsquirt
06-24-2002, 08:53 PM
yes, they interchange. Just be sure to get the correct piston for the rod you are using. Port timing was changed a bit throughout the years, as was the shape and size of the ports. nothing to worry about though.


-Dirt
Ed Grimly
06-28-2002, 12:05 PM
The reasoning I heard on the thicker head gasket was to reduce overheating.
:)