Can't say i've had an issue with stuck rings but modern two stroke premix oils are generally designed for the high revving engines which run much hotter than a trials bike which spends 90% of its time idling.
I have looked up the flash points for many of the oils you can buy to try and find ones ...

An easy fix for this is to weld a tab onto the swingarm which will accept the sharkfin of a modern bike.
That way when you break it, its cheap an easy to get a replacement.
all have the chain on the left hand side like the TY.

My TY80, need to rebuild the engine as the mains have seen better days but it runs.

We tig weld the scratch with a stainless wire on parts that we don’t rechrome or replace at work on hydraulics. 309L rod for carbon steel.
You then should be able to file this back and polish it in with an emery belt.
Can also dot weld on smaller parts.

Not sure what the kickstart is from Greg but by comparison with my CRF250 it looks very similar.

I recently saw online a 123 Cota modified to fit a XL125 engine with a TLR200 barrel which brings the capacity out to 167CC.
IMG_3204.PNG
IMG_3205.PNG

Has anyone completed the 4 stroke dream for some of the other manufacturers?
Yamaha could have had the TXTY by fitting a TY250 with an XT250 ...

Could you anodise the bottom end of a Alpina case Gold and the outer cases Blue, or would that be too much?

For that matter we could keep going, Triple trees, fork sliders, hubs, brake plates, I've got a set of Blue Renthal Handlebars.

I think you would follow the colour scheme wouldn't you?

For example, Blue for a 350 M199, Red for an M159.
Similar to Greg's colour scheme on the Squeamish.

David, in regards to the Chrome plated casings, have you tried using Hydrochloric/muriatic acid to dissolve the chrome plate?
Where I work we use Caustic soda and an electrical current to strip chrome but that is off steel, I believe this will have a rather deleterious effect on aluminium however.
I ...

One for the Yamaha TY80 Anoraks

What is the function of the Oil scraper No 17 in the parts manual?

It appears to me as if it would redirect oil flung from the clutch gear through a passage to the gear set on the other side of the crankcase but this would be in an oil bath anyway.

TY80 Oil ...