backfiring and wont rev

I have kz200 I have been working on here and there.

I bought it after finding in a garage for 20 some odd years. It has 11k miles on it.

I replaced the coil, points, plug had the tank cleaned and I put a new carb kit in it with the same size jets it had when I got it. They are the stock size.

The bike fires up real quick and will settle into a great idle. But thats it.... give it anything above 1/4 throttle and it sputters and backfires loudly.

The carb was pretty clean to begin with and I soaked it in yama dip for 2 days. It should be perfect. Nothing changes when messing with air screw.

I'm not really sure on what I should check next.

I am open for any Ideas or advice you can give.

deezil wrote:

...kz200...bike fires up real quick and will settle into a great idle. But that's it.... give it anything above 1/4 throttle and it sputters and backfires loudly.

The carb was pretty clean to begin with and I soaked it in yama dip for 2 days. It should be perfect. Nothing changes when messing with air screw....

Nothing changes when messing with air screw --- a classic sign of dirty carb pilot circuit.

If not already fitted, a good after-market in-line fuel filter is essential. Such as available from Z1E.

Would also assure the advancer unit is clean and lubed, and properly functioning. And NOT sticking.

Uncertain which carb is on the bike at hand, but here's a method to clean the pilot circuit in a Mikuni manual slide carb with side-located pilot air screw.

Good Fortune!

[Click on image to enhance view.]

Everything was cleaned with compressed air Everything in the carb is varnish free. All ports were checked over and over to make sure they were open.

It is a Kehien PW26 carb.

Points Ignition? Change out the condenser? Sounds like a condenser fault.

I have set being sent to me. I will try those out. I think it is coming with a condensor. Can I use a automotive style condensor if they don't come with it?

Should be able to, take 1 and hold it to the connections and see if it straightens out.
Best to convert over as you will be way better off, in the short and long term.