my r2j pulls cleanly to around 5k rpm.

after this is when the problems happen,

from 5krpm till the powervalve starts opens at around 7krpm the bike runs badly and barely accelerates.

when the powervalve begins opening it runs perfect and pulls hard till the redline.

the carbs have been cleaned.

has anyone an idea of what might be causing this problem.

When did it start to do it?

Have you made any changes?

Has it been stood?
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Mine was doing something similar and I found that one of the coil wires was barely plugged on to the coil.

MC18's are very sensitive in this area to jetting. It's often caused by a small lean area caused by the air box mod. It can sometimes be cured by re-oiling the air filter.
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If I have to take the carbs off once more...

i am running no air filter at the moment.

the airbox is not modified

i was running a homemade filter but it was causing the bike to run too lean so i just took it out.

i will be getting a proper filter soon.

i only bought the bike recently and it had been stood for years previous.

thank you craig

i sprayed contact cleaner onto the coils where the wires connect.

the bike runs perfect now very happy with it.