Rough running up to 2000rpm


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zalle
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Rough running up to 2000rpm

Post by zalle »

Hi guys, my 1979 Z is running a bit rough in low revs.

I thought it was carbs, but my mechanic tuned them.

What happens is: below 2000rpm, it feels like the engine is running on 4 or 5 cyls, a bit like when the petrol is running out and you have to turn the petcock to reserve. After 2000rpm it runs great.

I have aftermarket exhausts (similar to original but a bit louder).

Not really sure if this is electric or carb related, but maybe you guys can give an idea of what might be happening? Maybe one of the coils? Maybe the spark plug cables? Maybe none of the above???

Any help would be greatly appreciated.

Thanks

CBX Rui Barbosa.jpg
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steve murdoch icoa #5322
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Re: Rough running up to 2000rpm

Post by steve murdoch icoa #5322 »

Despite your mechanic tuning your carbs it sounds your idle jets still need attention.
Did the carb tune/cleaning include pulling the idle jets?

Btw, nice looking bike.

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tevan
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Re: Rough running up to 2000rpm

Post by tevan »

steve murdoch icoa #5322 wrote:
Thu Apr 08, 2021 6:24 am
Despite your mechanic tuning your carbs it sounds your idle jets still need attention.
Did the carb tune/cleaning include pulling the idle jets?

Btw, nice looking bike.
I agree I would bet on idle jets plugged.

daves79x
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Re: Rough running up to 2000rpm

Post by daves79x »

Guaranteed, it's the carbs. They need to come off and be completely rebuilt.

Dave

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zalle
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Re: Rough running up to 2000rpm

Post by zalle »

Ok... They did not come off, they were just tuned.
No easy way of doing this, right? They need to come off?

"Btw, nice looking bike." Thanks Steve.

daves79x
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Re: Rough running up to 2000rpm

Post by daves79x »

Correct, but most importantly, find someone that actually rebuilds CBX carbs to do it, not just a 'mechanic'. Ask around.

Dave

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zalle
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Re: Rough running up to 2000rpm

Post by zalle »

Thanks

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