1981 Kz650 carb tunning

I had project this spring. from painting my whole bike,replacing all the cables,plugs wires,made rear tail light. etc. also i put on vance & hines 4 into 1 and pod filters. I bought carbs that were rebuilt 2 season ago with probably under 3,000 on them. I put them on my bike stared right up and idled perfect best I've my bike idle! I reved it up red line with no load. it had no problem reaching red line.

I take it for the test drive its blogs out at 6000rpms. I couldn't get my bike to 60mph. automatically I think its running to lean.so I took off my pod filters and put my stock air box back on. problem didn't go away. still the same. but then I was getting 20mpg. the pick up was really good until 6000. I swap my old carbs back on bike was running a lot better it loss power at 7500 to 8000 rpm.

I took the new carbs apart. i didn't find anything weird they look a lot better then my carbs that probably havent had popper love in 10 years. I know the shop that rebuilt them doesn't have best reputation.

The main jet are 92.5


What would be the right size for me?

which carbs should I keep? I have to give the person I traded with a core.

i'm running 117.5 mains and 20 pilots, bike runs great.

sounds like you're running lean. if i was you i would try a 17.5 pilot and 110 main to start

Just a thought... have you checked for gas restriction/starvation? Petcock, gas lines, gas filter... Is your gas cap venting properly? Is the petcock vacuum line leaking? :huh:

Best of success.

del

yea the VM24 with accelerator pump.

yea there it only has one groove on the needle for the clip. I'm going to work on shimming it a little bit higher tomorrow. what are the measurement inbetween needles with grooves.

what do you think the right adjustment is for my set up 4 into 1 and pod filters? in 0.00mm?

The jet needles don't need to be shimmed. The problem you are having is lack of gas due to the main jet size. Use some #110s as has been suggested and #17.5 pilot jets. Verify that the accelerator pump is working.

I was kind of thinking (in the back of my head) that there might be a accelerator pump issue. because my other set of carbs work a lot better in the higher rpms how do I test it?