Bike bogs down @ 5-6000rpm

[Streetfighterz1000]

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.

[nazzurro_19]

is it maybe in the "limp home mode" ?

[slowsport]

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

[Streetfighterz1000]

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

[kevprojex]

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

[hannakournikova]

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?

[Cammo]

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

[Streetfighterz1000]

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

[Streetfighterz1000]

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