Kz900 misfire?

Good day,
My mechanic sent this video to show why he thinks a cyclinder is misfiring.
He says when he revs up a bit he can hear what sounds like a misfire in one of the cylinders. He had it connected to one of the meters to level out the carbs when he noticed.
What do you think?
Misfire

Hello Conspiracy

In my opinion motor runs to lean
Check fuel line, filter, jets, float high (clear tube test ) and vent in tank cap ( clogged = vacuum = insufficient fuel flow).

I am pretty sure he checked those but will double check. Thank you

and check your spark plugs.

Thanks for the great pic

Conspiracy wrote: I am pretty sure he checked those but will double check. Thank you

Love your avatar Conspiracy Penguin, I have the same issue which my GPZ1100, on idle - cold- it appears to be ok, but when the throttle is "slightly" open it backfires- sometimes. Previously my pilot jets were 38 (I have ZRX CV carbies) and the backfire was considerably worse - now I have 40 the backfiring is less.
I tried the idle jet mixer but could not see much difference apart from making it too rich - weird.
Opps forgot to mention, once the engine is hot there are no issues

Quick test for leaks in the intake manifold.
spray brake cleaner on or around the manifold, if motor rev lower you have a leak there.
spray brake cleaner in the air filter body to check motor without misfire.
sorry for my bad English, i hope you understand my explanations.

Valves adjusted?
Steve

Scirocco wrote: Quick test for leaks in the intake manifold.
spray brake cleaner on or around the manifold, if motor rev lower you have a leak there.
spray brake cleaner in the air filter body to check motor without misfire.
sorry for my bad English, i hope you understand my explanations.

Good call I'll check resealing - sorry penguin for steeling your thunder

Steve, not talking for Mr Penguin, yes I've just checked them.

Conspiracy wrote: Good day,
My mechanic sent this video to show why he thinks a cylinder is misfiring.
He says when he revs up a bit he can hear what sounds like a misfire in one of the cylinders. He had it connected to one of the meters to level out the carbs when he noticed.
What do you think?
Misfire

A lot of things can cause a misfire. Plugs, bad wire, cap, clogged jets, tight valves, etc. OR a carb way out of sync. Is he using a set of gauges or just one?
Steve

I'll have to get over there to check out his setup. I think he is using a set of gauges to sync the carbs.

If it's misfiring with the throttle open it probably is not a carb sync problem. Carbs out of sync can cause very erratic idling because the slides are nearly closed so any slight difference in carb flow has a profound affect. When the carb slides are lifted as when the throttle is opened the slight differences have less affect because the overall flow is so much greater. Ed