cbr 400 nc29 hesitation at 3k

[slyshot]

Hi Guys

Freshly rebuilt carbs, bike runs great now except for the fact it hesitates and gets spluttery between 3 - 3.5k then it runs perfect all the way through.

any ideas what might cause this?

thanks for your help

[dunkenb]

How wide open do you have the throttle when the problem occurs?

[Marmoot]

I'd like to know the answer to this as well.
Mine splutters like that when starting off , like from a green light.
I've adjusted idle speed is at 1500 rpm but that still doesn't help.
Once it gets over the splutters (provided it doesn't stall), it goes all chirpy happy.

[Davez29]

I had similar problems in the 2 1/2 to 3 range when I had stainless pipes fitted despite rejetting to suit. It seemed to be in the area tween pilot jets to main jet usage. Are you using different pipes to original, if so maybe thats part of the problem? I never fully fixed this and just put up with it until I found some original pipes as trying to rejet made no difference. Now its fine and the only thing I changed were the pipes.

[Marmoot]

Spot on! My bike came with Yoshimura slip on but I highly doubt there has been anything done with the carbs or plugs to support that.

I'll try switching back to the standard exhaust to see if problem disappears. If it does, i assume that means I must do something with the carbs if I want to use the Yoshi can.