hi
can i have some help with my mc21? i discovered my mc21 lost power starting at 7500rpm and struggled to spln past 9000. it also topped out at 130 km on a long straight at the track. i recently dropped both exhaust pipes, cleaned the power valves, checked the power valve motor as well. they all seem to be working fine.

i removed the airbox n checked the carbs today but the bike still run like very weak.

any suggestions and ideas

thank you

what condition is your air filter in? What about your battery? How fresh/stale is your fuel? How old are the plugs?

Hi,

Air filter is clean, battery is also new,fuel is good, and plugs are new but pretty dark after 2 trackdays.(bike ran poorly and had revving problem)

I started the bike today but it was having so much trouble to stay running and idle was rough.

Thank you again.

Hi
Check your ignition coils with a multimeter if they have the correct Ohm measures.I had a simillar problem with yours on my MC18 and it was the ignition coils.If you dont know how to do it take a look here at this thread http://nsr250.net/forums/viewtopic.php?t=11280&highlight=ignition+coils+check+cheque
It will helps also a lot if you have access at the service manual.
Good luck