6k and 12k rpm hesitation

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RotaryRobin
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6k and 12k rpm hesitation

Post by RotaryRobin » Mon Sep 10, 2018 7:03 pm

hello guys!

i have a 1988 CBR 400 RR nc23 RRJ, that doesent work as well as i want it to. well first off when i bought it the seller said it needed some cleaning to the carbs. so i striped it down, and had them cleand several times in an ultrasonic cleaner, then bought new O-rings for everything and put them back together with a set of new Ebay intake rubbers ( the old ones were hard as rock :whistle: ) well it didnt help. bike was still running like shit. so bought new sparkplugs and it didnt help. checked the CDI and it has and gold label as it should, but also a blue label one. tried them both and the bike is running equal shit with any of them. so what do i do next? i have tried ignition coils from a cbr 900 and it was running the same. it just feels that its lacking power, like it stops reving av 6k and then later on at around 12k it stops reving. and feels like it doesent getting fuel.

and also one other thing, i cant syncronize my carbs. all except the 3rd carb gives a reading on the tuner. has anyone had that problem before? i have a strange vacum sound on this hole inte the 3rd carb but none of the others, is it supposed to be like this? ( yes i know the rectifier leads are brokes, but thats fixed now)

Image

grateful for any help i can get!

/Robin.

moforockband
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Bike owned: GK73a SP CRM250 mk3
Re: 6k and 12k rpm hesitation

Post by moforockband » Tue Sep 18, 2018 10:07 am

Hi mate, check the following:

- check all 4 cylinder compression readings. all need to be healthy. (I'd guess above 150psi)
- check the throttle slide in that no3 carb against the others. - it may have a dodgy diaphragm.

N.

RotaryRobin
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Re: 6k and 12k rpm hesitation

Post by RotaryRobin » Tue Sep 18, 2018 6:11 pm

moforockband wrote:
Tue Sep 18, 2018 10:07 am
Hi mate, check the following:

- check all 4 cylinder compression readings. all need to be healthy. (I'd guess above 150psi)
- check the throttle slide in that no3 carb against the others. - it may have a dodgy diaphragm.

N.
Thanks for your reply Mofo, i will check the compression and that diaphragm next time im in the garage :grin: :peace:

RotaryRobin
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Re: 6k and 12k rpm hesitation

Post by RotaryRobin » Fri Oct 26, 2018 10:03 pm

i think i have solved the problem now, i changed the main jets to 110 instead of 115/118/118/115 and it now runs like a dream! :grin: so i hope it was this easy! :whistle:


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