If you think the head gasket is the culprit then it seems sensible to expect a loss of compression as the engine is breathing out of the sides of the motor rather than the valves as intended.

You will be losing compression unfortunately.

if oils getting out it means oil will also be getting in to your cooling system and probably the otherway round, does it smoke atall? (steam burning) id get it replaced asap

emto wrote:afraid not ,its the head gasket. ita a NC30. I did all the set-up myself before the dyno run, maybe the plugs were on their way out, but the question is, will I be losing compression with the leak?

Yes, but it might not be a lot.

Compression test it maybe?

You'll need a new HG if thats where its leaking from as oil / coolant may start to mix. Not the worst job in the world.

As for the bike.. theres plenty of reasons it might not be making original power.

How is the curve on your graph and fuel air consumption.. if there all 'nice' i'd be happy with that, it's better to have a nice running smooth bike.

The Hamster, not seen him post on here for a while spent hours messign with his NC30 and it only made 45bhp no matter what he did.

Potential Power Loss point.

Worn Chain / Sprockets
Dragging Rear Brake
Poor Clutch
Bad Air/Carb/Plug setup.
Worn Engine (i.e. bores)


I'd get your HG changed and maybe see how its performing then? :)