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Hey all,

So, have got the CBR1000 all dressed up in her new paintjob, shiney new exhaust and all. However, I have a problem with her...

When she is cold she is fine, but after a short ride, she backfires, splutters and struggles for power below 3000 rpm. I have changed the plugs, HT leads, and swapped the carbs for my spare set, problem still there. When she is cold, she is fine, it is just when she is slightly warmer. Over 3000 rpm, she pulls like a train, and is totally happy.

I am thinking it might be the HT coils, but can anyone suggest anything else I might check, where I might start?

Thanks
Stormme

just a guess, carbs need cleaning??

I think carbs are a good possibility. The HT coils shouldn't be causing this kind of rev-specific problem.

Your idle circuits in the carb are a good place to look - very small air and fuel passages lead to blockages. The bike runs fine when cold because it is runniong off of the enrichener circuit. Once you close off the enrichener, the bike doesn't have enough fuel flowing through the idle circuits to provide proper running.

Make sure that your idle air screw isn't out too far and also make sure that your carbs are sunchronized once you have cleaned them out.

Thanks Tech and Kar! I have changed the coils anyway, am just waiting for a chance to get the scoot out and see if they make a difference. If that doesn't make a difference, then I'll pull the carbs again and give them a good clean out. I am just surprised at it being the carbs, as I have tried 2 sets of carbs, same problems.

Aah well, process of elimination, will see how she runs with the new coils and HT leads, then pull the carbs and try again. If those don't work, then I think I'll just eliminate myself!

Just a question I have been pondering, when the bike is being revved, does the current to the HT coils increase, or is it constant?

Thanks guys
S.

It should be constant if your voltage regulator is functioning properly.