cbr400 starts but wont rev?

charge the batt/then clean the carbs,the bike will not run if the batt as a low charge, good luck.

Ross
April 2008

Did u put in new petrol and purge the fuel system of old fuel.and drain the float bowls on the carbs. I think your bike is too old to have an ECU think it's an ignitor box.You still need a new battery though.

NC21
April 2008

Hello,
Sounds like an ECU problem. I have seen them getting themselves in a "knot" when the battery is flat.
Try fully charging or replacing the battery and trying again, you should find that it is then OK.
Best regards,
Cliff

Cliff Patten
April 2008