tony27

Had to do the same thing to my 250s forks due to wear but used bronze, am using 17mm aluminium axles plus magicals springs & the updated damper rods which work really well

This is the seat I use on mine, they also have the mounting brackets available Trials Bikes :: Frame & Suspension :: Seats :: Yamaha TY250 Twinshock Standard Seat

Trying to remember if it was 09 that the cases changed with the waterways in a different place but basically what I'm saying is that the later cylinders probably don't fit I had my Jarvis cylinder replated last year, definitely the way to go as you know everything is perfect unlike if you buy secondhand

Have had the brakes start dragging bad enough to stop if the clutch was pulled in on a downhill slope while on a trials bike only trail ride, was expecting it to be time to rebuild the calipers but replacing the fluid fixed it in the front, rear brake was also in need of new pads as they were pretty well worn. I'd start with pushing the pistons back in the caliper, replacing the fluid & pads if they're worn

With a decent synthetic oil 70-80:1 is fine Biggest cause of clogged packing in exhausts is not getting the exhaust hot enough, if you ever do a decent climb that requires larger throttle openings for a few minutes you'll be surprised at how much the bike smokes & continues to smoke when you stop, a good trail ride every so often does wonders for keeping the exhaust clean

Ignition side crank seal is a possibility although I wouldn't expect the revs to go sky high instantly

1 thing that most 70s bikes & especially TYs benefit from is the bar clamps being moved in front of the steering stem either through buying a billet top clamp from InMotion or cutting the clamps off the standard top yoke & welding them back on, improves the steering no end & opens up the riding stance by more than you'd expect

I have a set for my TY250 from InMotion & knowing what it cost to have the stanchions on my CZ mx bike rechromed they are exceptional value, can't fault their customer service, were in my hands the next day

1 of our local twinshock guys runs the Tubliss system & hasn't had any problems with it

Beta & Sherco shared a few parts in the 2000s, fibre plates & pistons for the 270/290 for example.

If you look in the Beta section you'll find a thread on the fix, Sherco & Beta share friction plates until Sherco changed to the diaphram clutch. Basically the fix involves removing the excess glue between the friction pads

Correct front brake plate should be fairly easy to get, shared with the 125 & 250

The seals in the crank bearings aren't for sealing the cases, both Beta & Sherco who use the same bearings still run normal crankseals outside of the bearings

Is there a difference in width of the hubs between the older rim taped wheels & the flanged wheels? I recently bought a flanged rear wheel that has a polished hub & dark grey rim which I think would be from a 2019 20th anniversary model which there doesn't seem to have a parts book available online. The only hubs for the flanged wheels I can find part numbers for are fluro so I can't the numbers with the earlier polished hubs, none of the parts books show the bearing spacer so I can't even use that as a comparison I have used the wheel in my 04 Jarvis replica & noticed the disc sits closer to the inside edge of the caliper than the original wheel & the wheel is a tighter fit in the swingarm so I'm looking for reasons as to why this is the case

When you say you've bypassed the thermoswitch did you do that with a short piece of wire with 2 spade terminals plugged in place of it? That will tell you if there is power when the motor is running, I still carry 1 of those in my spares as insurance Your problem is possibly the rectifier for the fan which is 1 of the 2 small pieces up in the steering head Splat Shop - Sherco Radiator Fan Rectifier