My NC23 has developed a strange problem. She used to rev cleanly right through to 13000rpm no problem. A few days ago on the way home from work she started playing up. If I accelerate in any gear as soon as I get to around 8-9000rpm it feels like the engine is loosing spark or fuel and wont rev up cleanly (stuttering) as soon as I gear up and the revs drop she pulls cleanly again until 8-9000rpm right up the gears?????????
It started soon after changing the air filter and return throttle cable (re checked seem OK, may just be a coincidence) I have also recently replaced the down pipes the new set is slightly longer Oh yes and my speedo is sometimes wsorking and sometimes not. Any suggestions?????? Please help

Could be the speedo restriction playing up if your speedo's on the fritz?? Does it feel like it starts running on two cylinders?

Yes, it feels like one or two cyclinders are cutting out, as if they are being starved of fuel or getting intermitent spark. The speedo is in miles per hour, but the odometer seems to measure in KM (I know it is 7 miles to work, but my odo shows 11) does this make sense ???

Sounds like a mph dial put on a kph speedo . You probably wanna do the wire splice to the cdi to remove the restriction. Should stop it cutting out.

http://www.400greybike.com/files/NC23%20Res%20mod.pdf

Good to see my res mod instructions still being of use.

Easy fix once you get the resistor.