Engine Identification

dobba99 · 2025-12-29T00:31:29-0700

Hagarr said:
Thank you for your answer and knowledge.

Ok Clearly I need to delve further

I had considered checking cam lift if nothing else but i'll confirm bore size with mic and stroke.

I'll also need to look further into the boxes of bits for what may be a fix for the alternator end as the bike was definitely street ridden.

If it was ridden on the street it would have been in daylight only (no lights fitted as no alternator) Or if the bike had lights they were run off a battery, just not for long.

kommando · 2025-12-29T03:16:44-0700

Hagarr said:
Liners don't appear stepped as per the RGM kit, maybe stepped at bottom of bore.

The step will be at the top but hidden.

That way the liner cannot drop due to the step and the head stops it from rising.

If you remove one of the allen bolts then inside the hole you should be able to see the step.

marinatlas · 2025-12-29T03:25:21-0700

https://s3-eu-west-1.amazonaws.com/rgmnorton/fs/pdf/cylinder_liner_drawing.pdf

You check the diameter of the top of your liner and it should/could be 81mm ...?

kommando · 2025-12-29T04:07:02-0700

marinatlas said:
https://s3-eu-west-1.amazonaws.com/rgmnorton/fs/pdf/cylinder_liner_drawing.pdf
You check the diameter of the top of your liner and it should/could be 81mm ...?

Post #20 shows measured at 81.07mm with piston marked 0.5mm oversize, so possibly the old RGM 920 kit with the weak pistons. Norvil also did a kit but no details seem to be online of what it was made up of.

L.A.B. · 2025-12-29T04:28:17-0700

As far as I'm aware both the Norvil and RGM big bore kits originally had Cosworth pistons requiring the small ends to be bored out to suit the larger Cosworth gudgeon pin size.

marinatlas · 2025-12-29T04:36:11-0700

L.A.B. said:
As far as I'm aware both the Norvil and RGM big bore kits originally had Cosworth pistons requiring the small ends to be bored out to suit the larger Cosworth gudgeon pin size.

kommando said:
Post #20 shows measured at 81.07mm with piston marked 0.5mm oversize, so possibly the old RGM 920 kit with the weak pistons. Norvil also did a kit but no details seem to be online of what it was made up of.

Yes my mistake top of the liner should be 85.7mm not 81mm

Engine Identification

dobba99

kommando

marinatlas

kommando

L.A.B.

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