Cbr 400 nc29 - running issues

[slyshot]

Hi All

I have just rebuilt the carbs with a full oring kit and replaced the fuel filter, i gave the carbs a good clean as they were really grimy in the float bowls, i also checked the float height which was fine and have balanced the carbs.

Just took it out for a spin and its not running right, part throttle is fine but anything above a quarter throttle at any revs and it burbbles for want of a better description. it'll accelerate on part throttle then as soon as you wind it any further it suddenly cuts back and sounds like it has dropped a cylinder or two.

It has a full tank of fuel and the issue is on the reserve tap and the on tap.

Anyone got any ideas?

Thanks

[gullarm]

I would guess at an air leak around the carb rubbers.

Try spraying Ezi Start ( or any oil as long as its a mist ) around the rubbers and see what happens.

[slyshot]

ok great thanks, i will give that a try and see if anything happens, the carb rubbers are a pain to seat properly

Also I have taken the carbs apart again and one of the needle valves was stuck open, the spring would push in at all until I gave it a good knock, I ultrasonically cleaned the carbs a few weeks ago but when I opened them up this particular carb had a chalky residue inside and the stuck valve, seems pretty strange as they were spotless recently? Any ideas on this?

I’m hoping the float valve may have been the problem, I’ll let you know once they are back on at the weekend

[lamberhurst]

Hi Chum

I'm interested to know if you sorted this as I have exactly the same problem?

Cheers

C

[lamberhurst]

Hi All

Well sorted that now. It was a little water that had found it's way into the float chambers, just undid the drain plugs and let it out, all sorted now

[archeo14]

Helloo..
My cbr400rr nc29 is runnin on only 2 cylinders that is left cylinders and right cylinders are not working properly...
When i use wet cloth on left exhaust pipes they are very hot n in the same way when i use to both right exhuasts they both are semi hot...
Even i tried using hands on air intake on carbs, left both sucking air strongly n right both none:( ..
Since i am thinking about compression in piston is not good...so how to regain it back...
Change piston rings or piston?
And more over my plugs getting dry fouling even though i bought new air filter n plugs...


Please tell me