Chopping out at high RPM?

Im working on an 81' CSR1000 for somebody. I replaced the spark plugs because cylinder 2 was firing intermittently and i re screwed in the spark plug cap on that cylinder as well. I made sure they were gapped properly too. when you rip ass up the street on it and really give it the guns, it launches until about 4000 RPM and then it starts not firing on one cylinder. same as if you were just sitting there and revving it. It could be the carbs because if you pull the choke out when its misfiring, it seems to come to life for a second but then when you climb another 2000RPM it just starts misfiring again. does this sound like a bad coil or a ripped diaphragm in one of the carbs? i think its just cylinder 2 thats doing it..

Any help would be greatly appreciated.
Thanks guys,
KT

Brand of sparkplugs? I've had brand new NGK's fail right out of the box. Change to Denso W24-ESU's gapped to 0.032" and try again.

I think he bought Autolite spark plugs. I always thought NGK was a known good brand..

Their quality has slipped over the years. If possible try to get NGK's made in Japan as they have a plant in the U.S. making them too I'm suspicious of.

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because if you pull the choke out when its misfiring, it seems to come to life for a second but then when you climb another 2000RPM it just starts misfiring again

That sounds more like jetting/carb issues to me. If adding more fuel resolves the issue, then you're likely running too lean which could be as simple as a dirty carb.

also if your using pods at faster speeds more air is flowing in which leans you out i also think you have a carb issue not a spark issue

Pull those BS34s and clean them out thoroughly. take note of the jetting and be sure to blast cleaner thru all of the small passage ways in the carb while visually verifying the flow of the cleaner (where it goes, and if it comes out where it is supposed to). When blowing cleaner through the pilot tube in the bottom of the carb, the cleaner should easily flow through the 3 small holes in the top of the carb bore.

Check all the diaphrams which are probly fine, and set the mixture screws at about 1 3/4 turns out for your starting point.

The mains should be 122.5, pilots 37.5, and needle on the middle clip position.

Good luck.

Hes running a stock airbox and a Vance and Hines 4-1... Another guy that worked on it before me said that that bike was scary fast when he had it in his shop. So they say this stuff just started happening. Im gonna go out to the garage now and pull them wires out of the coils to check for oxidation looking stuff.

try running some carb cleaner through it. just add it to the tank and run it for a tank or 2.

well, i undid the compression boots on the coils. I totally thought i knew what was wrong with the guys bike when the plug wire popped out of the coil and there was metal wire that was flush with the insulator covering.. i thought that the metal stuff inside the wire had to be sticking out and you just jammed that into the coil.. nope, the coil looks like it just screws into the wire just like on the cap. no corrosion or anything like that. i put everything back together again, we'll see what happens when i put the tank back on and give it a crankin.