Trials Australia Forums

I'll be giving my TY a present at the end of the year..a new piston and rings. Where is the best place to buy it from? I think it will be a 1.75mm oversize.

Stu in the past I have used Wiseco piston kits for TY250 motor rebores and they have gone very well. I bought them through my local bike shop.
There is another brand now that seems to be well-regarded (Wossner) but I have not tried them. If you have a favourite motorbike shop you could ask them if they can get the Wossner or Wiseco pistons.
There is another good brand called Pro-X who make pistons for old TYs. They are based in Northern Europe and their pistons are made in exactly the same way as the genuine Yamaha pistons were. I've seen some of those used in TY175 motors and they are very good in that motor. Haven't tried one in a TY250 motor.
There are a few people selling old stock geniune Yamaha pistons and rings on eBay if you want to do a bit of searching yourself. One such person who lists some NOS Yamaha TY pistons is
http://myworld.ebay.com.au/beachyamaha/
but I haven't seen any TY250 pistons from him in a while and I think NOS Yamaha pistons only go up to 1.0mm oversize anyway.
In the TY250A, you can use a piston made for any of the twinshock TY250s. DT250 pistons are also suitable.
I'm sure John Cane could get you a piston kit very easily.
Regards
David

thanks Dave, I didnt know there was such a variety available! I'll check with the local shop tomorrow. The old girl has worked hard over the years so I'd better give her a new lung!

I used an unbranded piston and rings in one of my 250's when I built the engine back in 2006.Despite very careful boring and port chamfering it has always annoyed me how much the engine has rattled.BUT, since then it has not got worse in terms of noise or performance,having done alot of work since then including the Dartmoor 2 day last weekend.(For the fifth time)
So if you can get a NOS or Wiseco one then go for it,but a cheapo one may not be so bad either....
Craig Mawlem of Majesty Yamaha here in the UK is doing 270 conversions, on an exchange basis,so if the bottom end is in good nick it may be worth finding out what piston it uses and sourcing one locally.