Hello
Took the Nc30 track bike for a quick test ride today, starts up and runs fine, revs cleanly up until 5-6000rpm then feels like its being restricted or boging down and is an effort to rev any higher, any ideas would be much appreciated.

is it maybe in the "limp home mode" ?

could it be perhaps the vacuum pipe that goes to the fuel tap? perished or dis connected?

Vacum pipe is def on and in good nick, still cant figure it out

Have you taken the speedo off ? , if so you will need to add 2.2k resistor into the orange/blue wire to + feed.

So it doesn't rev past 5-6 or just bigs down?
If the first - then check your carbs are cleaned, balanced and jetted.
If the later then there is an electrical prob. Usually is something to do with derestrictor. Alarm bells ring when it's a track bike - has the speedo been removed?

hannakournikova wrote:Alarm bells ring when it's a track bike - has the speedo been removed?

+1

It's common to see peeps remove (or unplug) the speedo unit without realising the bike will then go into limp home mode (cuts spark to 2 cylinders after 5000 rpm). This can also occur if the blue/orange cdi wire is cut/broken.

If this is the problem it's an easy fix, just do the derestrictor mod - there's a guide in the document library: http://www.400greybike.com/docs.htm

Yes speedo was removed, didnt know about it messing with the rpm, will refit speedo and retry, thanks

All sorted now, fitted the speedo back on and worked straight off, easy when you know how!!!