Yamaha TRX850 Enthusiasts Forum

Have been thinking about this and would like someone with the experience to check my thought process

1 Press out TRX stem and press into R1 bottom yoke - what sort of force / size press does this require? Looks like TRX stem is straight fit in R1 yoke, but may neeed to weld / turn diameter, anyone know?

2 Make up Spacer to go under bottom bearing to compensate for difference in R1 / TRX yoke thickness

3 Fit 40 X 3/4" bore X 12 front wheel bearings to TRX wheel, may have to bore out bearing tube spacer to 3/4" ( any one know dimension of spacer hole? )

4 Turn down R1 front axle to 3/4"

5 bore out speedo drive to 3/4", will The speedo drive fit? looks like it will but may have to reduce thickness? How do I fit the anti rotation peg to the R1 front fork or can I rely on on the clamping force from the axle bolt?

5 bore out TRX spacers / make new spacers to centralise wheel.

6 Do standard TRX discs line up with 98 - 00 R1 front forks?

7 All the easy stuff bolting on R1 clip ons handle bar controls, mudguards - does anyone know where I can get the R1 mudguard grommets?

8 Adjust the ride hight, will have to remember to take measurements before the swap, ideally I want clip ons above the yokes. I have my front end quite low so should be able to do it, esp as I will maintain steering stem length.

Thoughs, help appreciated especially from those who have done this mod

will submit pics when complete - but this may take a while

same question here please

the bike is gonna be fightered so noo worries on clip on etc

im more interested in the stem pressin if needed

SDN wrote:Have been thinking about this and would like someone with the experience to check my thought process

1 Press out TRX stem and press into R1 bottom yoke - what sort of force / size press does this require? Looks like TRX stem is straight fit in R1 yoke, but may neeed to weld / turn diameter, anyone know?

2 Make up Spacer to go under bottom bearing to compensate for difference in R1 / TRX yoke thickness

3 Fit 40 X 3/4" bore X 12 front wheel bearings to TRX wheel, may have to bore out bearing tube spacer to 3/4" ( any one know dimension of spacer hole? )

4 Turn down R1 front axle to 3/4"

5 bore out speedo drive to 3/4", will The speedo drive fit? looks like it will but may have to reduce thickness? How do I fit the anti rotation peg to the R1 front fork or can I rely on on the clamping force from the axle bolt?

5 bore out TRX spacers / make new spacers to centralise wheel.

6 Do standard TRX discs line up with 98 - 00 R1 front forks?

7 All the easy stuff bolting on R1 clip ons handle bar controls, mudguards - does anyone know where I can get the R1 mudguard grommets?

8 Adjust the ride hight, will have to remember to take measurements before the swap, ideally I want clip ons above the yokes. I have my front end quite low so should be able to do it, esp as I will maintain steering stem length.

Thoughs, help appreciated especially from those who have done this mod

will submit pics when complete - but this may take a while

The one I've just done needed the stems pressing out, the TRX stem was 0.3mm too small to be a press fit in the R1 yoke so needed a few beads of TIG running around to build it up, then I machined it down to the correct size. The top hats need to be 22mm long, with an 11mm 'brim' and 11mm of material to fit inside the top yoke to take up the slack.

The R1 spindle is 22mm (7/8") so might not have enough material on it to stand being turned down to 3/4".

It's 'easier' to use a YZF750 front wheel

kaylaa

how much to do the yoke conversion ?

Speedo drive face will also need machining - have you thought about digital instruments?

NWS870R wrote:Speedo drive face will also need machining - have you thought about digital instruments?

Or like me use the TRX front wheel & axle with the speedo intact....

Killerwhale, how did u manage to retain TRX axle the thread on R1 forks is M18 from memory and the bearings are 17mm I/D.

Answers please

Regards

Simon

SDN wrote:Killerwhale, how did u manage to retain TRX axle the thread on R1 forks is M18 from memory and the bearings are 17mm I/D.

Answers please

Regards

Simon

I can take some mobile piccies, previous owner has made up alu spacers and a big chunk´o alu which fits the TRX spindle and is threaded on the inside...

An inner and outer threaded boss?
So it goes on the spindle after you`ve put it through the wheel but before the spindle and boss screw into the fork leg, isn`t that somewhat fiddly?
If I was going to do that type of conversion I would have drilled out the fork leg, tapped a larger thread in the leg then used an inner and outer threaded boss in the fork leg, recessed to an abutment face to secure it with some threadlock too as a belt and braces fix.
Surely the inner faces of the R1 fork legs need milling down somewhat too?

Killerwhale, photos would be good I have a newish tyre so I don't want to pay £70ish for new tyre + £50 - £100 for a new wheel.

What can I say I'm tight

Simon

SDN wrote:Killerwhale, photos would be good I have a newish tyre so I don't want to pay £70ish for new tyre + £50 - £100 for a new wheel.

What can I say I'm tight

Simon

...like it tight!

Thanks for that - brilliant!

Options as I see it,

Turn a bush, threaded on out side M18 to fit into R1 forks, threaded on inside to accept TRX axle and turn another bush to fit the plain hole on the other side of the R1 Fork. I could either make the bush an interferance fit, heat it and fit it to TRX axle, or split the bush and have it clamped by the R1 fork.

make another axle entirely 3/4" to fit 40 X 3/4" X 12mm wheel bearings with an 18mm thread one end to and suitable diameter other end to fit R1 forks. I would also need to mill some flat on the spindle to allow it to be tightened I then also have to mod speedo drive - hmm a lot more work - Killer whale your method is looking a definate winner.

1 other option is when at stafford show - Sunday, trawl through auto jumble and look for a suitable axle to modify - long shot??

any way thanks for the suggestions

Ahaaaa I see.
Yep that`ll work ok.But what about the speedo drive anti rotation lug and the milling off of the inside of the R1 fok leg lowers?
Oh and the Kagazumi discs, how do you find them?
I`ve had them on my TRX since I bought it, I like them at the price personally.

Mincehead wrote:Ahaaaa I see.
Yep that`ll work ok.But what about the speedo drive anti rotation lug and the milling off of the inside of the R1 fok leg lowers?
Oh and the Kagazumi discs, how do you find them?
I`ve had them on my TRX since I bought it, I like them at the price personally.

Don´t need anti rot. When the spindle is in it won´t go anywhere.
Bought them off sandys on e-bay

Hi there.
An R1 set of forks and yokes is my next project. Have yo got the dimensions of the additional spacers, it would speed up my efforts no end.
Cheers,