Hi guys,
just rebuilt my spare engine for my nc23 using the head and bores from the old engine as the big ends were shot and the spare engine was seized... now im having problems relating to the fuelling where it will sit at idle okish then when i try to give it some gas it will pick up revs then suddenly die

with the engine ive noticed its making a rattling sound (like cans being dragged by a car down the road), ive sat a screwdriver against the head, bores and the bottom end and it seems to be the bottom end of the bike. ive had the big ends and small ends checked by a proffesional mechanic before rebuilding the engine and he said it was all good.


Any ideas anyone?

Many thanks,
Adam.

Take the sump off and physically inspect the bottom end, make sure it hasn't picked something up during assembly.

You'll probably not have much choice but to disassemble and check.

Are the bearing shells in the top and bottom half of the crank matched to the crank? Or did you re-use the ones from two different engines. It's a bit unlikely to be the source of your rattle - I would have guessed there is something not torqued correctly.

the only things that has been changed on the spare engine is the Bores and the Head (and the gaskets obviously). so the crank is the origional afaik. plus i had it checked with the mechanic when he had a look at it. i've got a slight feeling that it may be a rattly clutch but feel free to tell me otherwise

Cheers,
Adam

have read some post linking this type of noise to the clutch springs. on this web page also cheers