So tried my trx engine in my big red frame

[toddy]

IVE GOT A NICE 250 BIG RED WITH A NOISY AND A BIT SMOKEY ENGINE, IVE RECENTLY BOUGHT A 300CC TRX TO PART OUT AND MADE MORE THAN ENOUGH FROM PARTS THAT IVE GOT THE ENGINE SITTING GOING SPARE SO THEY LOOKED VERY SIMULAR, ANYWAY TONIGHT I PUT THE ENGINE IN A SPARE 250 FRAME I HAD LYING ABOUT.FIRST IMPRESIONS WERE GOOD,EVERYTHING FITTED AND SEMED TO LINE UP UNTIL I LOOKED AT THE DRIVE SHAFT AND ITS NO WERE NEAR THE SUBFRAME ITS ABOUT HALF AN INCH AWAY FROM WERE IT SHOULD BE. TRIED SHUFLING IT FROM SIDE TO SIDE. ALL MOUNTS SEEM TO LINE UP FINE EXEPT THE ONE ON TOP OF THE HEAD. SO CAN ANYONE SHED ANY LIGHT ON THIS FOR ME AS IVE BEEN TOLD A FEW PEOPLE HAVE DONE IT BEFORE

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the frame is just a scrap one i had lying about to try it

[dougspcs]

Check the geometry of the final drive and see if it can be swapped from the Big Red motor..

[toddy]

thats what im messuring the now to see if its shorter

[6speedthumper]

I know the output shaft between 2wd and 4wd are different. If I remember right, that is an issue I had when I needed one for my 4wd 300. I had a 2wd parts bike, and it was different. So, after getting a good used one, I think I just had to take the 3(?) allen bolts out of it, and swap it out. Been years since I did it, may be a few things I forgot. Only other thing that you MAY have to do, is swap out the entire output shaft/final drive unit from the side of the engine, with that off the Big Red.

[oscarmayer]

you should be able to just use the output shaft of the 250 motor and install it into the 300 motor and it should work just fine. that is what most guys here do.

[toddy]

yeah thats what im going to do mate. ive got a meeting on sunday so will do it after then

[LastFoolerInVA]

you should be able to just use the output shaft of the 250 motor and install it into the 300 motor and it should work just fine. that is what most guys here do.

X2... I've read a lot of people do that: just swap the final drive 90 degree output shaft... but, be very careful as there is a thrust washer that loves to fall out of the shaft when it is pulled from the motor... and sad to say, I think the only way to get the washer back in place is to split the cases... there's a thread somewhere on here where someone did this exact swap.. I think he left the motor on its side & the washer stayed in place...also, the electronics on the TRX are differnet too... You'll need the wiring harness

[tripowersport]

toddy how did it work?

[Dirtcrasher]

X2... I've read a lot of people do that: just swap the final drive 90 degree output shaft... but, be very careful as there is a thrust washer that loves to fall out of the shaft when it is pulled from the motor... and sad to say, I think the only way to get the washer back in place is to split the cases... there's a thread somewhere on here where someone did this exact swap.. I think he left the motor on its side & the washer stayed in place...also, the electronics on the TRX are differnet too... You'll need the wiring harness

Nope, the washer can be retrieved with the kicker shaft and gear removed.

You can poll the right angle output shaft if you lay the motor down perfectly flat and remove the 3 bolts, gently tap it out.

There are oil holes that must align with the mating collar so turn up the lights and pay attention......