Standard piston to valve clearance, exactly the same set up in my engine last year with not one issue. There wasn't even any hints that valves were on their way out.

Anyway it doesn't get much worse, the engine is basically toast. I will dismantle it for spares although looking at the amount of shredded piston (it went bang flat in 6th) there might not be much! Hopefully the crank and gear box are okay, along with the new shells. I won't be holding my breath.

The plan now will be to recondition either the stock NC29 or bare NC23 head I have and put that on the old motor. I'll set that up with std carbs, and probably won't put the VFR gearbox or barnett clutch in it. Once that is together i'll sell it with a sizeable spares package! The money I get from that will help fund me onto a 600, and i'll spend anytime I get this year (if I get it this year) getting up to speed on the 600. After 41/2 months not riding my times on the new engine were shit. But some of that could have been the impending doom. Who knows.

Here are the pics:

Carl, I really appreciate your offer of a head but i have enough spares here to put together a stock one without too much expense. I have an NC29 head that needs a couple of valves replaced and it should be good to go.

Ah that sucks mate!

I hope you can string something together with your spares, be a pity to give up on it.

I know the feeling, second session out on my racebike after buying it I cocked up a gear change and blew the motor.

Greggo,
Thats pants man do you have an idea what caused the bike to choke.

shit man
totally frikken shit
if you want to put a full stock motor together i have some bits here to get you legal,crank and bits n bobs
maybe do a deal or summin on your knife edge'd crank
would be a shame not to see you out there this year...even if only in stock
and espesh as its the return of the stimpy!
chin up
stimpy

I don't know why it went pop. As I said, it's the same configuration as the engine from last year. I guess either a collet let go, or one of the valves has fatigued and dropped in. Considering the whole head from one of the valves is gone, i'm going to go with option number 1.

I do appreciate all the offers of bits guys. Right now i'm still deciding what to do. There is a nice damaged Triumph 675 up for grabs at auction prices...If I sell a running bike and parts....

mate that sucks the big one....maybe its a sign to move on.

taht 675 sounds tempting.

sorry to hear all that work and that happened friend . would like ur flatsides marcusgp127@hotmail.co.uk or some more race trickery

Greggo,

Really sorry to hear this...if you decided stay with 400cc put the list of requred bits - will try to help...

Marcus127nc29 wrote:sorry to hear all that work and that happened friend . would like ur flatsides marcusgp127@hotmail.co.uk or some more race trickery