1983 KZ 750 F LTD, carburetor re-jetting help

I bought a 1983 KZ 750F Ltd a month ago. its an inline four, shaft drive. the manual says it has a Keihin CV34. Its difficult to tell whether or not the jets have been messed with in any way. The manual specs for the carbs reads as such

(ZN750A)

Keihin CV34
Main Jet Pri. #68, Sec #90
Needle Jet 6
Jet Needle N10D
Pilot Jet #35
Main Air Jet Pri. #100, Sec. #60
Pilot Air Jet #110
pilot Screw 2.0 turns out
Service Fuel
Level 0.5 + 1mm

The guy i bought it off of was sort of into chopping bikes up and extending the swing arms and stuff and said the carbs were apart when he bought it. he said he put it back together and didn't do anything else to it. he had also taken off the stock airbox and put on K&N filters.

i'd like to keep the four into two pipes but do away with the stock mufflers and put on a couple of strait pipes. i'm told i'll definitely need to re-jet the carburetors to do that. is there a good starting point for that? can anyone give me advice? I have very little experience so please talk to me like i know nothing at all, seriously. I've ridden my whole life but was never inclined to work on my own bikes outside of maintenance, so this whole custom bike stuff is new to me.

thanks
jason

hello, carb jetting is not really a mystery but it is a trial and error kinda thing. No one anywhere can tell you exactly what jets you need. all carbs and motors wear in different ways depending on how they have been riden and maintained. So, what will work for one bike is not neccesarilly right for another similar bike. the best thing to do for you may be to put it all together with the parts you like(exhaust/pod filters/whatever)and get it running. at that point you will be able to see and hear how it runs and identify problem areas(poping/stalling/hard starting/bogging/), then the people on this forum will have more to go on and will be able to give better advice. we want to help we just need as much info as possible. They also LOVE pics!. in my experience changing the air filter to something like pods or stacks will make you have to rejet before changing exhausts will, but until you do it its all just guess work. I'd try to find out what stock jetting was and work up from there. get back to us.

thanks, i'll be putting the pipes on tomorrow. i'll run it again and write down everything it does. i took some new pictures of the bike but im not sure how i upload them on this site. i'll try and figure it out now.

thanks, more tomorrow.

jason.

well, heres my bike. most of the frame mods are done except for some minor details. i finished the seat and it not perfect, but it is homemade after all. the taillight fits into the slot i welded into the back and the back blinkers go on tomorrow.

Jay Bones... who? :laugh: Just kidding.

Pull the baffles, whatever. Ride it and see how it feels.

If the bike starts well and idles well, tahts good. It may have a slight popping sound from higher rpm when you let the throttle snap closed. That is the idle circuit, and can be adjusted via an external screw on each carburetor.

If it hesitates as you get on the throttle some, or flattens out while accellerating through the mid rpm, then you will need to adjust or change the needles in each carb.

When you pull hard full throttle above half rpm, if it flattens out or seems to make more noise than go, you will likely need new main jets to be installed in each carb.

I hope this informs you a little for now, as I have a feeling that you will find pulling the baffles will not make a very big difference in the power.

If it does, let us know, and we can educate you on just how to perform these changes, and any others if necessary.

Best of luck friend!