Only running on three cylinders

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Bobby dazzler
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Bike owned: CBR400 NC23, ZXR400
Location: Kettering, Northamptonshire
Only running on three cylinders

Post by Bobby dazzler »

I am having to admit defeat and ask for you good people's help. After refitting my carbs for the fourth time I just cannot get my nc23 to run on all four. Here's what I have done so far:

1. New plugs
2. Cleaned carbs and set float valves
3. Checked for spark and checked order of ht leads (1-3 2-4)
4. Checked float chambers for fuel

I am sure I have probably missed something off this list. Previously the bike didn't run on number two but after cleaning and refitting the carbs it is now not running on number three.

My uncle says that at 32 I am too old to learn mechanics, please help me prove him wrong.
The Novice
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Bike owned: NC23 NC30 CRM250
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Re: Only running on three cylinders

Post by The Novice »

mine did this - have you balanced the carbs? Although mine was only at idle when it was an issue, on the road it pulled fine, just at idle one of the headers only ever got luke warm.

You can check if its the pilot circuit - i think its pilot at low revs. Been a while since i thought about carbs - let it idle, feel the headers (or spray water on it if your a wimp), one is probably cold, then give it some revs, like 5k for a 10 seconds, does it get warm/hot then? If it does, then its obv firing.

Balancing sorted mine out - there is prob a thread of mine somewhere about it on here.
Bobby dazzler
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Bike owned: CBR400 NC23, ZXR400
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Re: Only running on three cylinders

Post by Bobby dazzler »

I tried revving the bike to 5k for 10 seconds and I do get a little warmth through the header. Is it a difficult job to balance them?

Thanks
The Novice
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Re: Only running on three cylinders

Post by The Novice »

its not difficult, you just need a set of gauges. Haynes manual will guide you through it or check out a few how to clips on you tube.

swap the plugs over and check its not that.

Have you ridden it, after its warmed up etc you might find it settles down.
Bobby dazzler
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Bike owned: CBR400 NC23, ZXR400
Location: Kettering, Northamptonshire
Re: Only running on three cylinders

Post by Bobby dazzler »

I swapped the plug for a spare to check and it made no difference. I can't ride the bike as it was a very cheap project which needs a complete looking over. Currently it has no clutch or brake lever, no calipers attached and whoever had it before me decided to cut the valves out the wheels.

Thanks again.
stimpy
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Re: Only running on three cylinders

Post by stimpy »

I think you have a leak in your inlet manifold.
Either the 1 of the manifolds is stuffed(perished or split)
The carbs arnt seated properly in the manifold.
Or the clamps are loose.
I'd be looking at that
See how u go
Stimpy
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Re: Only running on three cylinders

Post by stimpy »

P.s,your never to old to learn,at 39,I'm a boilermaker,qualified car suspension repairer and as of late...1st year fitter and turner apprentice as part of my job lol
Basic mechanics and racing bikes is my past time
kiwi racer
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Re: Only running on three cylinders

Post by kiwi racer »

stimpy wrote:P.s,your never to old to learn,at 39,I'm a boilermaker,qualified car suspension repairer and as of late...1st year fitter and turner apprentice as part of my job lol
Basic mechanics and racing bikes is my past time
But doing things half arsed dont count :whistle: :sshh: 8-)
kiwi racer
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Bike owned: CBRs
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Re: Only running on three cylinders

Post by kiwi racer »

Is the sparkplug on the non firing cyl wet or dry ?? if you have fuel in the carb there is no guarentee its getting to the plug to go Bang and the spark may be too weak to actually go Bang properly. Also have you checked there is some compression on that cyl ??
stimpy
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Re: Only running on three cylinders

Post by stimpy »

kiwi racer wrote:
stimpy wrote:P.s,your never to old to learn,at 39,I'm a boilermaker,qualified car suspension repairer and as of late...1st year fitter and turner apprentice as part of my job lol
Basic mechanics and racing bikes is my past time
But doing things half arsed dont count :whistle: :sshh: 8-)
Dammit Paul It's to early here to think up a comeback!!
Well played sir....well played.

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