As 80XAR says, check the jetting first. You never know what someone has done (or tried to do) to it before you took possession. Standard carb settings can be found in the Workshop/Technical section.

When you are sure the carbs are set correctly, ensure the RC Valves are set up accurately. You could disconnect the RC Valve cables and pin them open with a "knock pin". It'll run like crap at the bottom, but should take off about 7~8000rpm. It won't necessarily rev right out, as the alignment holes aren't always that accurate, but if it pulls through 8k nicely, it's probably identified the problem.

This is all once you have checked/cleaned the air filter and fitted new plugs first, of course!

One last thing, if the battery isn't 100%, it can cause very similar symptoms on the MC21.
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Andy.
NSR-WORLD.COM

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