charadam

Cracked it - at least, I think so. On my service manual, a small shim is shown that acts as a spacer behind the "ring" (0000 913 0510). This shim is not shown in my IPL and is missing from the saw. The result is that the sprocket drum is being forced laterally on to the clutch when I tighten to the 29.4 N/m, causing the binding. Job for tomorrow, turn a shim/spacer on the lathe and I should be OK.

"Can you still turn the engine by pulling the chain round the bar with it in place but not the side cover clamped up ?" Good question and I see the logic. Will try tomorrow.

As stated in earlier posts, the sprocket and clutch are new, OEM items. The sprocket is within a few thou of round and is well finished. The clutch springs are stronger than the ones on the old clutch. The sprocket does not rock appreciably on the shaft. There has to be a misalignment somewhere but for the life of me I cannot diagnose it. The clutch works perfectly without the chain and bar but the moment the bar is fitted the engine can be turned by pulling the chain.

This was in response to s.varty. No, the clutch drags too much for the engine to start. The powerhead runs perfectly without the bar and chain.

Yes it does.

Yes it is. It is a new, OEM part and the springs are strong.

My old 08S clutch started slipping and was showing heat damage. I replaced the clutch, clutch sprocket and the needle roller bearing. The crankshaft is straight and runs true to less than .001" measured by DTI. The powerhead starts and runs perfectly until the bar and chain are fitted. The chain then is driven by the starting cord (clutch dragging). The bar is straight and the chain in good order. There is obviously mechanical interference which is causing the drum to contact the clutch shoes, but believe me the fault is not apparent. Desperate cry for help!