RS34 Jetting on a KZ1000

davel wrote: beefsquasher wrote:

The head has been ported. I'm not that happy about it, and it was like that when I got the bike. Fill it in? I hear that porting/big valves/etc. is basically worthless on these bikes for street use and serves only to take away midrange.

-Dave

My experience supports this hypothesis. I've done some extensive testing and tuning with port volume and have found no significant gain in HP from enlarged ports on a mild performance build. Increasing port volume only serves to reduce low/mid range torque, throttle response and fuel mileage.

The port on the left has a removable epoxy insert. On a 1075, 365 cam, RS34s, and 4-1 w/performance baffle, the open port (on the right) makes only about 3 more peak hp than the one with the epoxy insert but sacrifices torque, throttle response and fuel mileage.

Jetting for the two ports is similar with the difference being needle position. #3(center) clip postion for the open port and #1 position (leanest) for the epoxy port - Higher intake velocity at part throttle produces a much stronger signal at the jet hence a leaner needle postion. Both require a 125 main jet.

I've noticed that the guys with the most trouble tuning out carb related bogs and stumbles have enlarged intake ports...regardless of the carb they are using. I also had these issues until installing the epoxy inserts.

more info here
kzrider.com/index.php?option=com_kunena&...d=2&id=235189#238454

The port on the right on my motor is cut farther to the right.

This allows a straight shot to the intake valve seat.

I lost torque, response and all that.

Mostly when I took off the 26mm carbs.

Your carb may indeed be too big Watson

The rpm the bog occurs will change dramatically with ignition timing

and cam lobe center changes as well.

you got work to do :woohoo: