Yamaha TRX850 Enthusiasts Forum

I've done lots of searches of the site & can't find a definitive answer to the machine sprocket carrier/fit offset drive sprocket conundrum. As I understand it the first option means the chain won't align with the slider on the swingarm

Simple and easy. You modify the rear sprocket carrier.
This allows you get alignment and utilise the std trx sprockets front and rear with no special 1 off offsett front sprocket.
Look at where your rear sprocket sits, you remove the 6 threaded studs and machine the 5mm raised section the sprocket sits on and bingo.
Others have argued the plastic runner near the front sprocket wont align but I had no issues at all with the std trx swingarm. Others who have centred the wheels and machined the brake side of the swingarm pivot have had no issues either with the yzf750 swing arm. ( they didn’t need to remove material from the sprocket carrier either.
Main point to remember with the 5.5” Yamaha rims, the hub is 5mm wider and hub to rim alignment is the same on the brake side as the trx 5” rim.
But the hub to rim alignment is 5mm wider on the sprocket side.
With no bracing on the thunder race swingarm, you should be able to sit the trx swing arm on top of the thunder ace to get an idea on centring the front and rear wheels too and if the pivot tube needs either spacing or machining or is all good.
Align the rear brake sides of the swing arm because they are the common factors with the TRX and thunderace. Same spacing and brake caliper mount and same hub/rim centering.
This will give you an indication of the swingarm pivot to centre the wheels.
Or take it to a certified motorcycle engineering shop that straightens frames and modifies bikes for side cars etc and have it all lasered and centred like I did.

From memory I think there is 10mm difference ( 260mm trx/270mm Ace) between the inside spans of each swingarm at the axle end. 5mm will obviously be taken up by hub width. The other 5mm will be in spacer/top hat from the axle/wheel so measure against the std wheel spacers to find your difference.

You can see the sprocket carrier mod in a photo here


http://www.trx850.com/phpBB_forum/viewt ... rm#p101311