Topic: No power after 4-6k, cylinders 2 and 4 not firing

[JeVightHawk]

83 nighthawk 550, I rebuilt the carbs, new spark plugs, new petcock, new fuel filter, new air filter, cleaned tank, have compression…
Bike hasn’t ran in 12 years. After carb rebuild it starts right up every time and idles right around 1,100 but sometimes after riding it stops at 2k and then goes back to 1,100. There’s loud backfire at idle though and occasionally at low speed. When I accelerate there’s just nothing. I couldn’t get on highway if I wanted. There’s no difference in some throttle, half, or WOT. Cylinders 2 and 4 are always warm but I could rest my hand on them. I bought new coils but somewhere in this forum I read that if that were the case then no cylinder would fire since 1 and 4 share and 2 and 3 share.

Ignition timing? Manual is confusing on how to check or adjust. Can’t find any vids as they’re always 70s cb550 and when I look at mine they’re different.

Valve clearances

Clutch slipping? It revs up to 5-7k but nothing is projecting me forward yet it doesn’t feel slipping up to those speeds.

Any questions to help me figure this out I’ll be glad to answer.

I’m about to spend $150 to have it diagnosed but hoping I can try more before I get to that point. Thanks again. Sorry if I posted in forum wrong. I always seem to say wrong thing. Appreciate the time.

[scottly]

Cylinders 2 and 4 are always warm but I could rest my hand on them. I bought new coils but somewhere in this forum I read that if that were the case then no cylinder would fire since 1 and 4 share and 2 and 3 share.

On the sohc bikes, the coil on the left side feeds 1 and 4, and the coil on the right side feeds 2 and 3. Do you have the correct wires connected to the correct spark plugs? Try swapping the 2 and 4 wires.

[HondaMan]

You 'rebuilt the carbs', words that scare me half to death if non-OEM parts are used in these bikes.
Where did you get the parts for the carb rebuild, and did you keep the ORIGINAL brass parts in the carbs? If not, go back and put those back in. None of the aftermarket brass parts are correct for Keihin carbs on any of the Fours I have worked on. This kind of performance problems are exactly what appears when non-Keihin brass gets installed.