Hi all , firstly thanks for all the help so far but here comes the next set of questions

ive just stripped the bike down and dropped the motor thats popped (previous owner) and had a look under the cam cover and nothing stands out as particularly trick slotted cams etc?. is there any way of telling if its deffo an sp really easy? someone said they have more clutch plates but exactly how many?

just making sure the engine matches the chassis etc

The sp has 9 plates in the clutch as opposed to the standard rr clutch which has 8.there are some bits of the top end that are marked in green(cam buckets i think) and the rr cam buckets ere marked yellow.h0pefully someone with a bit more knowlage will be along to confirm this as i am old and a bit forgetfull!!!!

lift the cams out & pull up a cam bucket if its a sp it will have a yellow dot, or green if its a RR

thanks for the info but im proper confused now. its got the 9 plate clutch but the dot in the bucket is green with yellow valve springs? at least the bores are in mint condition and the pistons are good as well as no head damage. looks like its just damaged one botom end shell. will strip it and check its the close ratio gearbox. any obvious signs? undercut gears like the hrc ones?

SP first gear ,has more teeth than the rr in the g-box. the rr should have 43 teeth if i remember correctly,cant remember what a sp has. when you say it has bottom end damage it might be wise to do the oil way mod now its striped.to prevent it happening again if you ride it hard it will happen again

thanks, i will have a look when were back from the manx. oil way mod?

Oilway mod - I think it goes like this ...

The 400 and 600 have the same crankcases but 400 has a sleeve in the oilways. Under some racing conditions the oil to the big ends can suffer so the sleeve is taken out.
Yours will probably have been done if it's a race engine.

these things blow up a bit easy! i have a con rod on the bench and the engine is still in the chassis.. manx is over for the yam.