Yamaha TRX850 Enthusiasts Forum

Can someone confirm that Japanese home market forks are the same 41mm diameter as the European ones?

Race Tech have cocked up with their catalogue and have the TRX springs at 43mm

They are, because they use the same seals. Racetech have listed the wrong ones for the TRX for years..

Thanks Snod

RT are changing their catalogue but I was just making sure they hadn't been given info for a different model.

They've also been pretty helpful by giving me a selection of valve springs and valve plates with extra holes for the low speed damping. I'll post pics at the weekend. I've been struggling to get the front end right - especially as the rear is so good with the Ohlins set up well.

Do you mean springs and shims for the emulators? Because that's pretty interesting! Last I heard the new big thing was to have a progressive spring in the valve but that was over a year ago and tech moves fast.

I have YSS PD valves in mine and they're not quite right but the fork springs are too hard (went by Racetech's calculator but it seems to be for the track?) so could be my own fault. Still like it way more than stock though, if only for the slower rebound. Mine's a bit weird - Hit a speed bump slowly and the front rides over it but hit it a bit quicker and the forks collapse a bit and give a more comfortable ride. It's also hard below 60MPH, great from 70-90MPH and then a bit wallowy beyond that. How's yours?

I'm just about there now. Just some fine tuning but I'm getting pedantic.

On blue 40 lb emulator spring and 3 x 3.2mm holes in the low speed valve below the emulator spring. Running 15 weight Motul oil at 150mm air gap. I'm about 82 kg wet.

My initial problem was similar to yours - great over high speed "sharp" bumps but too firm on undulations and small, low speed bumps. It made the bike pitch a lot. The 40 springs at 3 turns and additional holes made a big difference - no more pitching/running wide and chatter. The original valve plates only had one 3.2mm hole. I also think the RT calculator is for the track - I'm on 90 kg/mm springs too - I would probably have gone for 85s in hindsight, although the new plates have really made so much of a difference the heavier springs are less noticeable. I haven't seen/received the progressive emulator springs.

I'm running 85kg/mm springs but am only 70kg without gear (66kg when I bought them..) and the sag is very small.

No idea what plates or how many holes are in the YSS valves but I'm about to buy a pair for another bike so will have a look!

Keep in touch - I might be able to help you out with bits if they're compatible (they probably are as YSS are a copy of Race Tech )

YSS Valves arrived yesterday, looking at them today the plates/shims/whatevers only have one hole in, too. The hole is small though, maybe 1mm in diameter, but then these valves are only 17.5mm in diameter going into some CB250 forks so everything is smaller. It will be interesting to see how it rides as I will be keeping the original progressive springs and these smaller valves have a softer spring in them at 7N as opposed to the 12N springs in the larger valves (including the ones that fit the TRX).