idel issue and doesnt run ryte below 3k

I just recently purchased a 1981 kz 750e. it was running a little rough when I bought it so I replaced plugs, wires and caps, main vaccume lines off the carbs added a fule filter and also changed the carb boots, and a new battery. the reason I changed the carb boots was because they were cracked and dry rotted. I was wishing that that would solve my problem but it didnt. Ok so heres what shes doing to me. The bike starts up but will not run with the choke off. I turned the idel adjustment up a little but it just didnt help. Now if I leave the choke on about have way so the bike can run it sounds like its misfiring or something? Now if you take the bike for a ride it studders untill 3.5k and then it picks up and starts running normal.

this is just something i was looking at and had a question about. The regulator that came on the bike is still there but disconected.I though that it mite have been replaced because it looks like there is a new silver one screwed to the bottom of the battery box. The plug that is pluged in to the new looking regulator looks nothing like the plugs that plug into the regulator that is disconnected

i m not sure about the electrical part, but it sounds like your pilot jets are plugged up.....you can put a tester on battery and rev it to 4k or so and see what ya get for charging..sounds like somebody replaced regulator and left old one on....usually if it isnt charging right, it is fine down low and farts and falls flat as rpm s rise..you have the opposite problem, which makes me think its carbs...
i m sure the smarterer folks will chime in....good luck

Pictures help. PO may have switched regulators and left the old one.

For the idle, if your bike still uses points, check those. Also the cam chain (tighten). For the carbs, it could be pilot jets, or float height thats messing with the idle, or the carbs may be out of synch.

Have you ridden it yet? If so, how did it run at higher rpms?

I just had a similar problem my bike was doing all the same stuff yours is. My carbs were full crap and after I cleaned them it idles and runs good.
Tom

thanks for the help everyone. I guess I will be taking the carbs back out. but this time I will clean them

Ok I cleaned out the carbs and it runs worse. At first it ran ok but once i shut the choke off it started running like crap. I tried to take it for a ride and now it feels like its running on 2 cylinders. Im going to let it sit and cool down and try and start it again and check how many volts it has when running at 4k. The bike also sounds like one of the cylinders is backfiring.

Maybe I'm wrong here but I'll open my pie hole anyways...

You originally wrote where the motor would only run with the choke on... This informs me anyways, that the carb jetting/adjustments are set too lean...

At 3/4 throttle to WOT it works fine above 3Krpm which would be your needle and main jets. Seem to be about right...

So as mentioned, your pilots are whacked in their adjustments or PO has the wrong size jets installed.

Pilot jets are mainly for idle to ~ 1/4 throttle...
Needle jets range from 1/4 to 3/4 throttle...
NOTE: These jet's somewhat overlap each other as well!

After cleaning the internals out, do a bench synch and set according to Shop manual specifications. This will at least get you in the ball park....

RECORD where they presently are at (screws number of turns out) and take pictures....

Or your starter pipe/jet is clogged/malfunctioning.

Just some thoughts...

OMR

Here's the jetting chart for the Keihin CR Specials to give you an idea of the jet ranges and over lapping operations...