Yamaha TRX850 Enthusiasts Forum

Has anyone else used Wossner for forged pistons? My motor has been stripped and found to have some of their forged pistons. Just wondering if anyone can let me know what the lead time for a set of new pistons would be?

Unfortunately along with stuffed rings it has been found that my bike has been running lean and has slightly melted and ovaled the pistons.

Not heard of any other members using Wossner pistons but you could contact them to find the nearest stockist to you, likely in Australia actually.
Here is a link and phone number:

http://wossneronline.com/CustomPistons.php

The reason I gave that link above is because they do not list TRX pistons in their catalogue, I`m guessing they were a special / custom order.:

http://wossneronline.com/2011_motorcycl ... atalog.pdf

All the pistons are moly coated on their skirts too it seems.

Wossner Piston Kits:

Wössner forged pistons are made for 2-stroke and 4-stroke engines, and are supplied in kits which include rings, clips, and pin. All pistons are moly coated for superior lubricity and long life. 4-stroke pistons are supplied with custom DLC (Diamond-Like Carbon) coated wrist pins, providing anti-friction, high RPM motors.


She was running THAT lean? It`s very unusual for a TRX to run lean, they nearly always run on the rich side.
Do you have stock carbs or flatslides?

Just found this company, they stock / sell Wossner :

http://www.compsystems.com.au/contacts/ ... sales.html

http://www.compsystems.com.au/products/ ... ssner.html

Seems they run tight piston to bore tolerances.

Cheers mincehead, I had a quick look on their website/catalogue so had seen they didnt list them - only thing similar would be a YZ425F but I don't think you'd want to run MX pistons in a TRX! I had however been to their website before and the only reason would have been for looking at hi comp TRX pistons but I couldn't find any link to the site on here - maybe it was from a dutch TRX site!?

I'll have a browse through the links when I get home, unfortunately my bike is in Auckland, NZ, and I am at work at Olympic Dam, South Australia, so I can't phone the mechanic at the moment, a friend in NZ is looking after the bike for me so the information is second hand. The bike is running FCR41's and has an OVER 2-1 system that had a shot exhaust cannister so my only assumption is that either the FCR's weren't tuned very well - I put air filters on them as it was running open velocity stacks when I got it ex-Japan, or the exhaust blowing/burning the baffling out would have caused it to go lean. I'm guessings it's probably a combination of the two.

I'm not a racer, but in recent times I had spent a lot of time on track back in NZ and also doing some uh... 'spirited' road riding too. I had noticed that the temp gauge was creeping up (110deg) as of late but put it down to the engine working hard as it didnt seem to happen so much when just getting around.

I'm just wishing I'd stripped it and freshened up 18mths ago rather than doing it now that it's a bit poked!

I VERY much doubt the Over system having a blown can packing would have any bearing on it, much more likely the motor has been getting too hot.
Maybe some of the damage that is making itself evident had been done while the bike`s FCR`s were un filtered and you`ve just been `topping it up` so to speak. Check the cooling system thoroughly when you strip it down too.