BS34's on the Kz650 help

I was able to mount my kz1000 carbs on my 650 (both 1981's) see this thread:

kzrider.com/component/option,com_joomlab...id,3/id,54235/#54235

and it seems to start ok. I have removed the airbox and want to try to see if k&n's will work and hoped to get some advise. I think that the main jets are 22.5 or 122.5 based on a number that was stamped on them. I don't know the size of any of the other pars but I assume everything is stock.

I need help calculating any jetting changes that I may need to make based on the larger carbs and putting pods on. Later I hope to put a 4-1 exhaust but for now the stock 4-2 is on the bike.




Post edited by: nosxiH, at: 2006/09/03 22:51

Post edited by: nosxiH, at: 2006/09/03 22:52

With K&N pods, use #140 main jets and #40 pilot jets. Your jet needles won't need adjustment and the only adjustment would be by shims anyway since there is only the one slot / circlip on those carbs.

34's with 140 mains on a 650? That is how you told me to set up my 1000. Wouldn't that be too much fuel for a 650? Especially with 4 into 2's

The main jets are needed because of air flow and rpms... I have tested 650 BS32s, GPz750 BS34s, cop bike BS34s and KZ1100 BS34s with pods and all of them like #140 main jets. Using 4 into 1 pipes or 4 into 2 didn't make a great deal of difference.

WG-I appreciate your comments on trial and error vs. experience. I understand it's 40 pilot and 140 main with pods on BS34's 650-1000cc Kawi's with factory needles and settings.

What's your experience with the same carbs and stock airbox all else same as above?

It never does any harm to put #40 pilot jets even into a stock set up as the #37.5s are on the lean side but leave the main jet stock size if you use the stock airbox. You can jump the main jet a little and do no harm but will soon run rich. The main jet sizes on the 34s vary wildly and according to how restrictive the airbox and the application.

WG- Yeah my bike defintely needs the pilot circuit richened up. Popping coming off throttle, slow to warm up to smooth operation, not as smooth as the rest of the power band @1/4 throttle or less below 3-4k rpm. I'd did a rebuild with 112.5 and the bike runs great above 1/4 throttle with improved response thru the whole band.

As such I will be installing the 40's. As I run a Kerker 4-1 and K+N in stock airbox and I'm going to break the carbs down anyway....do you think running with larger mains than 112.5 is good idea. Please check my logic below.

I was looking at my manual KZ750L3 '83 and it indicates a stock main of 110 with the option of 115 for racing. Is it a fair guess this 115 is with stock exhaust and stock airbox and filter? Extrapolating further is it also a fair guesstimate that going with Kerker header and K+N in stock airbox you would bump up to 120 on the mains or would you stick with 115/112.5?

Your experience is greatly...greatly appreciated.

WG- Yeah my bike defintely needs the pilot circuit richened up. Popping coming off throttle, slow to warm up to smooth operation, not as smooth as the rest of the power band @1/4 throttle or less below 3-4k rpm. I'd did a rebuild with 112.5 and the bike runs great above 1/4 throttle with improved response thru the whole band.

As such I will be installing the 40's. As I run a Kerker 4-1 and K+N in stock airbox and I'm going to break the carbs down anyway....do you think running with larger mains than 112.5 is good idea. Please check my logic below.

I was looking at my manual KZ750L3 '83 and it indicates a stock main of 110 with the option of 115 for racing. Is it a fair guess this 115 is with stock exhaust and stock airbox and filter? Extrapolating further is it also a fair guesstimate that going with Kerker header and K+N in stock airbox you would bump up to 120 on the mains or would you stick with 115/112.5?

Your experience is greatly...greatly appreciated.

WG- Yeah my bike defintely needs the pilot circuit richened up. Popping coming off throttle, slow to warm up to smooth operation, not as smooth as the rest of the power band @1/4 throttle or less below 3-4k rpm. I'd did a rebuild with 112.5 and the bike runs great above 1/4 throttle with improved response thru the whole band.

As such I will be installing the 40's. As I run a Kerker 4-1 and K+N in stock airbox and I'm going to break the carbs down anyway....do you think running with larger mains than 112.5 is good idea. Please check my logic below.

I was looking at my manual KZ750L3 '83 and it indicates a stock main of 110 with the option of 115 for racing. Is it a fair guess this 115 is with stock exhaust and stock airbox and filter? Extrapolating further is it also a fair guesstimate that going with Kerker header and K+N in stock airbox you would bump up to 120 on the mains or would you stick with 115/112.5?

Your experience is greatly...greatly appreciated.

does tightening the air screw up to richen the mixture do the same thing (in the end) as installing a new pilot jet, or would you just be starving the engine for fuel?