Yamaha TRX850 Enthusiasts Forum

Sorry if this is a dumb question - have been trying to figure out using the "search" function just what I'm going to need to do a fork conversion.

Can anyone who has done it or otherwise happens to know, tell me what parts I'm likely to need to convert a standard TRX front end with bluespots to a pre-'03 R1? I was thinking this subject area, if not my post, might potentially be a useful sticky here, seeing how many hard-core enthusiasts here seem to have done a similar conversion, and the limitations of the standard forks.

Presumably I need some or all of the following:

Old pair of R1 USD forks (duh)
R1 top and bottom yokes (both? just one?)
R1 stem (?)
R1 axle/spindle & co.
R1 front wheel (or can the TRX one be used?)

TRX clip-ons
Existing brakes, switchgear, etc.

Thought I had seen or heard of people using some combination of TRX and R1 yokes, but that's one of the things I'm unclear on. Can you use TRX bottom yokes and the R1 top yoke? I've seen one complicated thread on this and it seems like R1 yokes and stem were used. Not sure if this was for bling factor, or there was a functional reason.

Thanks in advance for any advice.

Can't help on the R1 conversion how-to, but just reading thro wot you wrote, note TRX clip-ons won't fit R1 USD forks, and check your existing bluespots are off an R1/R6 as if they're Chundercat etc bluespots, they won't fit R1 forks (I think) due to position of brake line bolt.

Alternatively, YZF750 USD fork conversion how-to: Remove front ends, swap stems, refit , have a cup of tea and admire...!

is it just yzf750 forks/yokes/clipons needed?
does the standard TRX wheel/spacers fit?

trixynut wrote:Can't help on the R1 conversion how-to, but just reading thro wot you wrote, note TRX clip-ons won't fit R1 USD forks, and check your existing bluespots are off an R1/R6 as if they're Chundercat etc bluespots, they won't fit R1 forks (I think) due to position of brake line bolt.

Alternatively, YZF750 USD fork conversion how-to: Remove front ends, swap stems, refit , have a cup of tea and admire...!

Thanks! Another 'duh' moment for me on the clipons.

So if one can find a 750 front end, it's a straight swap? Do the bluespots matter on the YZF forks? And as Tony said, what about the front wheel?

Of course the big problem these days is finding said front end, unless you buy a complete YZF!

YZF front end: nothing is the same as TRX except: discs and ignition switch, and you can use the TRX throttle/levers/master cylinder/switchgear etc on YZF bars.

Not sure about the wheel? Looks the same, and maybe yzf spacers/bearings in a trx wheel make it a yzf wheel?

Standard TRX calipers or R1/6 bluespots (not Chunderace) will fit, or obviously YZF calipers.

YZF speedo drive is same connection type and ratio as TRX, so takes TRX cable.

so...assuming its a standard TRX to start with....to do the swap i'd need :
YZF750 forks & yokes
YZF750 clipons/bars
YZF750 discs
YZF750 wheel spacers - what about wheel spindle? is that the same?
YZF750 speedo drive
YSF750 ignition barrel (or will the TRX one fit?)

the front wheel is not the same. iirc the bearing od is bigger on the YZF, as is the speedo drive.

You can do the following:

R1 front forks + Brakes.
R1 top and bottom yokes.
R1 front wheel,brake disks, spacers and wheel spindle.
R1 clip ons or any aftermarket clip on bars.

Press out the R1 stem from the lower yoke.
remove TRX 850 stem from the lower yoke,
Take to engineering firm to have TRX stem fitted to R1 lower yoke, shorten the stem and have a top hat shaped spacer made for the R1 top yoke.
Fit to TRX
Job done....

TRX discs are not the same as R1s

Whatever you do, you will need a complete front end

YZF750 retains speedo drive

trixynut wrote:YZF front end: nothing is the same as TRX except: discs and ignition switch, and you can use the TRX throttle/levers/master cylinder/switchgear etc on YZF bars.

Not sure about the wheel? Looks the same, and maybe yzf spacers/bearings in a trx wheel make it a yzf wheel?

The discs are not the same (YZF = 320 mm) but I think you already knew that.

About the wheels, that is an interesting question: if yzf spacers/bearings in a trx wheel make it a yzf wheel?
I should check the codes on the rims on my bikes next time.

TonyDevil wrote:so...assuming its a standard TRX to start with....to do the swap i'd need :
YZF750 forks & yokes
YZF750 clipons/bars
YZF750 discs
YZF750 wheel spacers - what about wheel spindle? is that the same?
YZF750 speedo drive
YSF750 ignition barrel (or will the TRX one fit?)

"spindle", is that the same an axle?
Then the YZF one is (way) bigger then the that from the TRX.

youngy wrote:the front wheel is not the same. iirc the bearing od is bigger on the YZF, as is the speedo drive.

Affirmative. The front axle of the TRX is so tiny compared to the YZF it is almost cute

idl1975 wrote:Do the bluespots matter on the YZF forks? 8<

As stated before, the YZF has 6-cilinder calipers, which are good but not as good as blue-spots.
I fitted bluespots (well actually they are silver) on my YZF, big improvement. Although I had to modify the brake pads, because the braking area on the 320mm discs is quite small. I sold the 6-cilinders this week...

This winter I will brake down the YZF and fit every interesting part on the TRX!

when i did mine i did not use any trx bits except for the steering stem ,,but then i did have a complete undamaged R1 front end off my crashed R1,,one thing for sure if you stick to using just R1 bits everything will fit

there was a complete r1 front end missing the wheel for 250 on ebay last week. its got all the clips, yokes spindle, brake and clutch levers and master ccylinder, no blue spots. if i had the cash it would be in my bed room waiting to be fitted to my bike.

its at a shop i think iys still there.

thats a good price !!! wheels go for about £200 complete with disks ,so for £450 your all in

rocketrose28 is the name of the seller and the item is 280234817453. have a look its a a bargin

Thunderarse front wheel will fit and will give a working speedo drive - the bottom of the LH (I think) fork-leg needs work to accommodate it.

I snagged a TA wheel + discs and tyres for less than £50.

G