1982 kz750 csr twin carb problems

Hello everyone I just purchased a 1982 zx750 csr twin and it was running a little rough so i decided to clean out the carbs. After that the bike would start but quickly stall out with a backfire of gas out the carb. the spark plugs are black when i pull them out and the carb is fitted with pods. I'm not sure if the carb was ever jetted correctly. Still has the stock exhaust. I've tried searching for a solution but got no luck. Maybe someone can point me in the right direction. I just want to be able ride my new toy.

With backfiring, first thing I would do is verify the timing advancer is working correctly. My 1979 750 twin has BS-38 carbs, I think that yours may have BS-34s (?) Not sure about jetting for pods.

the spark plugs are black

Are you sure it's not oil? The 750 twins are notorious for valve seals failing which will let oil run onto the plugs. Guess how I learned that......

For carbs, first thing I would do the following before trying to tweak jets:

1) Take the tank off and drain it. Rinse clean with mineral spirits.

2) Clean the petcock.

3) Install new fuel filters.

4) Check carb fuel levels with clear tube.

Hello everyone I just purchased a 1982 zx750 csr twin and it was running a little rough so i decided to clean out the carbs. After that the bike would start but quickly stall out with a backfire

Is it running worse after the cleaning? It sounds like the carbs may still be gunked up. Could be problem with pilot system.

Or bad carb holders.
Steve

Insufficient intake valve clearance can result in backfire through the carb.

Good Fortune!

I finally got her running again! Thanks for all your suggestions! I found the tank was filled with crap so I cleaned all that out of it, then I made sure my carb was clean and put back together correctly. Put everything back in and fixed my electric start (yeah I was kick starting it the whole time). Hit the button and she fired right up and runs perfect now. I found some chewed up wires going into that 12v regulator under the seat and re wired them. That could of been the issue the whole time.

You don't happen to have the stock airbox setup do ya? More specifically.. the ducts to the carb?

Nah sorry man my bike came with pods on them already

Seems to be the case with most. What jet sizes are you running?

Somehow my engine seized up on me today while ridding. Luckily I wasn't going to fast. Drained my oil and looks metallic. So now I have my head off and I'm having trouble pulling my cylinder head off. Any suggestions??

Can you rotate the crankshaft at all?

Yeah I can turn the engine by the crank so I'm guessing it's something with the kick start or transmission. Any suggestions?

What do the plugs look like?
Steve