Wont rev past 8k

[Racer93]

Hi,

I built a race bike from a box of bits and when we had a shake down on a track day it wouldn't rev past 8k whilst driving.

I could force it too by kicking it down a gear and ragging it, it would then rev to the limiter 14k ish.

The carbs are CV with the air screw on the front blocked off etc so I assume they are off a race bike.
I cleaned them with petrol and an airline and re-jetted them as they were.
105 mains I think. washer under needle...

Any ideas please? I took it to a dyno and they didn't even know where to start.....

It's a newly built Rich Bearcroft motor with race pipe, total loss, ram air, good motor, just runs rubbish....

I hope to do Thruxton next month so some advice would be very much appreciated.

I'm considering splashing out and fitting some flatslides but reading the forum it seems like a lot of expense for possible even more problems.

cheers

Martin

[banner001]

105 mains seems a tad low for a ram air setup even with the air jet blanked off...but if you ask the racers what they use on a similar setup they will be able to help you better.

Easy enough to diagnose on the fly, just before the bike bogs give it full throttle and keep rotating the throttle, if it now revs fine you are too lean on the mains.

Raising the needle with a washer and blanking the main air jet are all ways to richen the system, I would suspect that it needs even more though.