Yamaha TRX850 Enthusiasts Forum

Noticed quite a few r6 forks... (size?? 41mm or are they 43???),,,/complete front ends/99 to 06 models on e bay..(new toy I've found t o play with ). ... Can anyone tell me is this a viable option for my TRX or are the forks too short once steering stem has been modified to accomodate or can I use the std 41mm steering stock.. thanks

Pretty sure that they are not 41mm so not a straight swap

yes had it confirmed that they are 43mm. With a measurement of 755mm from centre of axle to top of fork leg (not the cap) from memory the trx where around 840mm ish so I'm thinkin that may be a little short? Or are my trx measurements wrong? If short what implications will this have to the handling?
Doing this while in hospital after a scapiod operation so cant just run downstairs... damm or park the bike by he bed

cobbadiggabuddyblooo wrote:yes had it confirmed that they are 43mm. With a measurement of 755mm from centre of axle to top of fork leg (not the cap) from memory the trx where around 840mm ish so I'm thinkin that may be a little short? Or are my trx measurements wrong? If short what implications will this have to the handling?
Doing this while in hospital after a scapiod operation so cant just run downstairs... damm or park the bike by he bed

Get well soon cobber!

Remember later R1 forks are VERY short, and lots of people are using them with no major troubles. It's the whole issue with the yokes that makes them unpopular, I reckon.

Thanks digga.
While talking to the man on the moon after getting out of surgery and yes the moon is made of green cheese.(oohh morphiene )I figured that the handlebar clamps on top of the trx yoke was where this measurement was taken and the r6 top yoke does not have this so I would gain a little length thereby using the std r6 clip ons on the forks themselves. Fairing ???thats the next thing I'll have to think about if the r6 .handlebars will fit in the std fairing.. Then theres the fork stops that stop each lock Left/right of the forks if that will need a mod also? Also have to look at speedo set up on the r6
Have given up trying to track down the thundercat forks and unfortunately dont have $1000 to do an r1 mod.

cobbadiggabuddyblooo wrote: Have given up trying to track down the thundercat forks and unfortunately dont have $1000 to do an r1 mod.

Rather than changing the forks, have you consuidered having the standard ones professionally reworked? Decent springs, new valves etc specifically chosen for your weight and riding style is money well spent. Especially bearing in mind that if you buy second hand forks, the chances are that they are going to need a complete overhaul to make a noticable difference

Have to agree with phuk there. I sent my forks and shock to Terry Hay at Shock Treatment in Sydney,he rebuilt and rechromed forks and rebuilt shock,new springs front and rear to suit my weight,gold valves etc for a tad over $1400, best value i reckon .Very happy with the transformation. I also was looking at R1 forks but couldn't justify the purchase price plus the rebuild cost then the shock

(edit) rechrome of fork legs was $400 so you can take that off what i paid if you don't need that done.
I also had my FJR done there last year, feckin transformed

Yes remembered looking at rebuilding originals(10mths ago) with new springs and different damping set up for around $500/$600 from memory so I think this option is looking better as time passes. Have to remember aussie dollar was worth 95 U.S. cents then.
With almost another 20hp found since first dyno ed at 70.6 hp (now with fcr's and exhaust mods) and blue spots..suspension is really letting me down.. But time to fine tune that over the next two /three mths,, the plott thickens

cobbadiggabuddyblooo wrote: With almost another 20hp found since first dyno ed at 70.6 hp (now with fcr's and exhaust mods) and blue spots..suspension is really letting me down.. But time to fine tune that over the next two /three mths,, the plott thickens

As any racer will tell you, sorting your suspension is the key to quick lap times. This should always be the first port of call before adding power!

BTW, if you sort the front, be prepared to spend some money on the rear shock as well

Yes is doesnt stop does it with tyres and rego also not to mention the noisy camchain and 98,000km on the clock and shims due.. But thats all a part of the fun and the art of tuning and dynamics..even if it keeps me broke..

Interesting indeed. I brought my trx with a set of r6 forks already installed, I did discover that they had slightly bent legs,so i purchased 2 new inner tubes, made a huge difference. The top and bottom yokes have been bored out to suit the 43mm legs, along with the trx clip ons. It also runs a 183mm dog bone at the rear, jacking the rear end. With the r6 forks set flush with the top of the bar clamp, there is no worries with bottoming out. The forks are at 23.5 degrees, running B/Stone 120/60 front, after riding this set up for 3 years, with a few adjustments to fork oil, rebound, etc. over bumpy mountain roads, I can't fault this set up at all.

Back again, other things to consider, r6 front axle is larger diameter, r6 forks have a different speedo drive. To keep the TRX front wheel, you will need to go larger on the inside bore of the wheel bearins, the r6 bearing spacer needs to be shortened to suit the trx wheel. The speedo drive can be retained, this too needs to be bored to suit the r6 axle, I pay special attention to drive mechanism when installing the front wheel, as there is no rebate in the left fork leg to locate the speedo drive, I make sure it is located correctly as the axle is tightened. This can be a major issue when you have the front wheel installed by a bike shop, after new tyre being installed etc, if the drive unit rotates during the axle being tightened, it can cause the leg to be forced out of alignment.

I've been slowly building the bits to do this, whilst also considering all kinds of other hair-brained options, I'd thought it was a bit more bolt-on than reading this thread would suggest. I don't really have the appetite for a new set of clocks or alternative speedo drive. A previous owner had fitted stronger springs and oil but you can still feel the thing going squirrely when pushed hard.

I contacted Maxton (UK) about fork internals and they came back with three options;

1. A rebuild on the 5EB forks I've got with new springs and cartridge mods to suit my weight and a full rebuild for £430+vat.
2. A cartridge conversion, new springs and a full rebuild for the original TRX forks for £610+vat.
3. As above but with a fully adjustable cartridge system for £710+vat.

I can't see that the 5EB forks are going to be any stiffer than the originals, given they are only 2mm oversized on diameter. I don't mind reworking yokes (if needed) or fitting 5EB yokes but I don't want to loose the original speedo, has anyone done a work around?

The only way to go USD and keep your speedo drive is to go the yzf750 front.

I ended up using emulators for a number of years and sprung to my weight and made a massive difference.
A lot cheaper option than maxton quoted you too.