DOWN ON POWER

SECTOR · Post by **SECTOR** » Mon Jun 26, 2006 9:24 pm

Hello,
I have just purchased a race bike zxr 400 sp.
The engine is fresh built, Kent adjustable cams, 0.5mm o/bore, stainless valves etc etc.
It has standard carbs with proper air box, Carbs in air box and trunk to front through rad.
The bike is a ex road zxr400SP. The engine is not SP.
It should be capable of producing 70+bhp in this state.
It has been on dyno and is producing 62 bhp DIN.
No one knows why it is down on power.
One possible answer is that it has the standard SP black box, could this be restricted.
I am not a mechanic and am desperate for clues.
How do i know if it has the correct black box etc.
It has a total loss ignition system retaining the starter motor. The speedo has been removed.

chris4356uk · Post by **chris4356uk** » Mon Jun 26, 2006 10:28 pm

is it a uk bike or an import???

Chris.

chris4356uk · Post by **chris4356uk** » Tue Jun 27, 2006 6:39 am

If the Ignition box is from an Import SP then it will be stopping it reving out as the Ignition box is no longer conected to the speedo, but I would have thought that as soon as you disconect the speedo that it would not rev properly anyway.
If it is the case that the ignition box is from an Import SP you will need to find out how the speedo would limit the revs, ie some work electronicly & some work on the speedo needle getting to a certain MPH/KPH before cutting in on the rev limiter, so you will need a deresticter.

Roger Middleton (rmkd177) is the man to speak to on this one I think as he used to have a lad racing a ZXR400 SP so he should be able to through more light onto the subject.

Chris.

kris-cross · Post by **kris-cross** » Tue Jun 27, 2006 10:40 pm

Roger Middleton is the man to talk to he works on zxr 400's for a living
'He's the man that can'!