I bought an NC 23 a few weeks ago with a little damage (most of the plastics gone). I thought the engine was okay but it runs poor above appr. 5000 revs. I already changed the spark plugs, the air filter, cleaned the carburetors (ulrasonic - is this the right expression? ) - no change at all. I even checked and cleaned the filter of the fuel tap - still the same.

Does anybody have an idea what to do next? The fuel pump seems to be working, as far as I can see it in the fuel filter which seems to be clean as well.

Do I have to check the CDI?

The engine is running pretty well from idle speed to the revs mentioned above so I don't think I have a mechanical problem. In this range the engine seems to run better than the one of the NC29 that I also own.

Finally I want to mention that I try the bike without the instruments and displays because they have been damaged too and I'm waiting for the ones I bought in England. Can this cause any problems?

It would be nice if anyone could help me solving this problem because I want to rebuild the bike with an aftermarket fairing from Hongkong or the lovely kit from Tyga - but first the engine has to be running perfectly.

Sorry for my english but I'm a bloody German!

Not 100 % sure on this but i think you may need the clocks on it. The reason i say that is there is a limiter of sorts that cuts the engine, try a search on here
http://www.400greybike.info/newforum/vi ... restrictor" onclick="window.open(this.href);return false;

it will be the ristrictor cutting in because you havent got the clocks connected