TS125 Broken Plastic Chaincase

[Guesi]

As I wrote, their purpose was to break in case of a chain break....
And that happened quite often due to the poor quality of GDR chains.

[Jay Bee]

Throwley -
As Guesi says, made to be broken in the interest of preventing further damage. They're relatively cheap to replace, after all.
The chaincase on my ETZ125 had been comprehensively smashed by the p.o. as a direct result of chain breakage - caused by popping wheelies.......
In the course of replacing the case I found a number of rollers/sideplates/pins stuck inside the r/h. engine cover and chain tubes, etc.even though the chain had been replaced by the time I bought the machine.
The original cylinder barrel was ruined by the shop grinding away part of the outside finning (to fit their boring table ?) - no big deal but should not have been necessary - and then boring it out of perpendicular. They then completed a very rough rebore by grinding chunks out of the port windows which even extended into the bore. I was not best pleased with the result, but felt a sense of real satisfaction some time later when I heard that the company had gone out of business.

[Throwley]

The original cylinder barrel was ruined by the shop grinding away part of the outside finning (to fit their boring table ?) - no big deal but should not have been necessary - and then boring it out of perpendicular. They then completed a very rough rebore by grinding chunks out of the port windows which even extended into the bore. I was not best pleased with the result, but felt a sense of real satisfaction some time later when I heard that the company had gone out of business.

Say what???

That's a complete horror story! Mine's being bored today, can't pretend I'm not worried now.

[Puffs]

Removed

[Jay Bee]

I've bought a DID 428HD chain for my bike - not fitted yet, but it's a lot "chunkier" than a standard 428. Might even be too chunky for the availiable space.......
Re the rebore, piston-bore clearance (tolerance?) didn't even come into it - I don't have instruments to accurately measure the bore anyway. The actual bore sleeve protruding at the bottom of the oem cylinder measured the same thickness all round before boring and noticeably thinner on one side than the other, after. This tells me that the bore is now no longer perpendicular to the base (or cylinder head face) or not centred on the original bore, I believe. Assuming that the new bore is actually the same diameter top to bottom, of course.
The piston is a 1st. o/size K20 supplied by a reputable parts dealer. I bought another used (pattern) cylinder on std. bore and have had that rebored to suit the same piston, by someone else.

[Puffs]

Removed