Yamaha TRX850 Enthusiasts Forum

Got this complete r1 front so cheap I just coudn't resist it.
Making several searches on the forum, I can't seem to find the posts covering a TRX-R1 front swap. The more detailed the better.
There are som references to a zip-file on the old trxfiles-site. But I guess that site is down for good??
Can anyone please lead me to the information I need?

Odd Arne
Norway

Sorry for my soso english ...

zod wrote:Sorry for my soso english ...

Until I saw that and 'Norway' I'd assumed english was your first language.

It has been covered, I've read it, I just can't remember where!

That front end looks good though, you've got a good starting point having everything.

I started going down this route with my TRX but discovered that you need to either have a new stem machined which will match the TRX steering head dimensions AND the R1 bottom yoke diameter (trx stem is too small in diameter to fit the R1 bottom yoke), or you need to build up the bottom of a TRX stem with weld and then machine it back to the R1 stem diameter where it goes into the bottom yoke (there are some photo's of this on the web but they took some puzzling out).

I was all geared to fit a set of R1 forks like this when I realised that the R1 forks are about 57mm shorter than the TRX forks and I thought that a little excessive! (although others have done this mod with no problems)

I ended up tracking down a brand new set of YZF750SP forks and doing that conversion instead. Its much easier with the YZF forks as the TRX stem is a direct fit into the YZF bottom yoke and makes everything else a straight swap. The YZF forks are also shorter than the TRX forks, but only by 35mm.

Good luck, let us know how you get on

Terzikat wrote:I started going down this route with my TRX but discovered that you need to either have a new stem machined which will match the TRX steering head dimensions AND the R1 bottom yoke diameter (trx stem is too small in diameter to fit the R1 bottom yoke), or you need to build up the bottom of a TRX stem with weld and then machine it back to the R1 stem diameter where it goes into the bottom yoke (there are some photo's of this on the web but they took some puzzling out).

I was all geared to fit a set of R1 forks like this when I realised that the R1 forks are about 57mm shorter than the TRX forks and I thought that a little excessive! (although others have done this mod with no problems)

I ended up tracking down a brand new set of YZF750SP forks and doing that conversion instead. Its much easier with the YZF forks as the TRX stem is a direct fit into the YZF bottom yoke and makes everything else a straight swap. The YZF forks are also shorter than the TRX forks, but only by 35mm.

Good luck, let us know how you get on

the trx stem is not smaller and it will fit the bottom yoke from an R1 you do have to make a spacer that is 10mm for the under side of the top yoke ,,,if you use blue top forks 1998/2001 you will be fine , if you use 2002 on,, gold top then they are 10mm shorter and you will still be fine ,,later ones are better because they have better damping ,,,the std trx forks stick though the top yoke 43mm but the R1 clipon goes under the top yoke

If you are that bothered about the steering stem, can't you use YZF yokes with R1 legs?

phuk72 wrote:If you are that bothered about the steering stem, can't you use YZF yokes with R1 legs?

No. R1 forks are a smaller dia than the YZF bottom yoke holes.... I had to turn YZF forks down to fit R1 yokes (the very ones fitted to your TRX in fact...)

As Steve says; an R1 front end will fit a TRX steering stem with one simple spacer under the top yoke (as fitted to PHUK's TRX in fact...)

R1 forks are ~40mm shorter than TRX.. So you gonna have to get around that, or just have the front dropped slightly. As you can see, i made a special adaptor to my triple clamps. but thats only one way of doing it. Many people dont need to mod as its perfect for them.

yes but does the 40mm not just stick though the top of the std forks ? so by fitting R1 units the bike is at the same height

honkdawillydahonk wrote:

phuk72 wrote:If you are that bothered about the steering stem, can't you use YZF yokes with R1 legs?

No. R1 forks are a smaller dia than the YZF bottom yoke holes.... I had to turn YZF forks down to fit R1 yokes (the very ones fitted to your TRX in fact...)

As Steve says; an R1 front end will fit a TRX steering stem with one simple spacer under the top yoke (as fitted to PHUK's TRX in fact...)

that explains that then

steve speed wrote:yes but does the 40mm not just stick though the top of the std forks ? so by fitting R1 units the bike is at the same height

I think that would work if the stems were the same length but the TRX stem is longer, so the R1 lower yoke has to sit that much further down the fork leg, effectively shortening the fork by the difference in stem lengths.

i dont think it does,,,,, when i did mine i took a measurement from the ground to the underside of the bike i got the same measurement when i fitted the R1 forks ,, and yes the the bottom yoke is lower on the leg than it was on the R1

Kayla wrote:

steve speed wrote:yes but does the 40mm not just stick though the top of the std forks ? so by fitting R1 units the bike is at the same height

I think that would work if the stems were the same length but the TRX stem is longer, so the R1 lower yoke has to sit that much further down the fork leg, effectively shortening the fork by the difference in stem lengths.

Are you perchance barking mad?

It doesn't matter where the bottom yoke is as long as the top yoke is roughly the same height off the ground. Steve's right; as the TRX forks stick through the yoke (forget the clip ons for a second) by about 40mm or so you can get away with running shorter USD forks, as long as you mount your new clipons under the new top yoke. YZF forks will give you more-or-less standard front ride height.... R1 slightly lower. Either is absolutely fine.

now let that be an end to it !!!!!!! R1 forks,, do, ,have, , will ,, FIT ,... all you need to do is bash out the old stem insert trx stem , make a 10mm top hat shape spacer i will give you the sizes if you like and there you go ,,,o and it may cost about £500 for the conversion maybe a bit less if your lucky

honkdawillydahonk wrote:

Kayla wrote:

steve speed wrote:yes but does the 40mm not just stick though the top of the std forks ? so by fitting R1 units the bike is at the same height

I think that would work if the stems were the same length but the TRX stem is longer, so the R1 lower yoke has to sit that much further down the fork leg, effectively shortening the fork by the difference in stem lengths.

Are you perchance barking mad?

Apparently so... Ta for clearing that up. I'll shut up now

steve speed wrote:all you need to do is bash out the old stem insert trx stem , make a 10mm top hat shape spacer i will give you the sizes if you like

Yes please!

Thanks alot to all of you!
I'll try to ceep this post updated on my progress for anyone who wants to try out the same modification.