Jet needle improves acceleration.
22 Nov 2012 04:23 #559582
so, I noticed the following 4 cylinder kz models, when researched have the following hp to bore x stroke ratio's, all being oversquare(bore larger than stroke)
-80 kz550 fx makes 58hp, 58x54
-80 650 f, about 64hp 62x54
-80 750 l 74hp 66x54
-80 1000 ltd 95 hp 69x66
-2004 z750 68x50 100 hp
-2004 z1000 77x50 127hp
so if the larger bore makes bigger hp per cc vs torque then why mess around.
Hi. I have this very same bike with thew very same problem.I put pods on and fabbed a 4-2-1 header. It is very lean during the mid and was lean on the top, but not as bad. Ran a 125 mainjet and she's too fat. Going back to a 120 main and going to run a different needle. I turned my needles down by hand and it got significantly better, but I screwed the off-idle up. I am convinced that I am on the right track with a needle swap. Going to run a 5FL14. I will post the results.
For carb tuning considerations, if not already aware ---
Main jet size has no effect on air/fuel mixture until after 3/4 throttle, and has most effect at wot where the jet needle is high enough in the needle jet to allow all mixture available from the main jet to pass through the needle jet.
Jet needle taper and position in the needle jet (plus slide cutaway) governs air/fuel mixture from 1/4~3/4 throttle.
The pilot jet governs air fuel mixture from idle~1/4 throttle.
Up to 1/4 throttle position on large Kaw fours produces a surprisingly brisk road speed.
There is a progressive transition as the jet needle takes over from the pilot jet, and another progressive transition when the jet needle thereafter surrenders to the main jet (as the main jet supplies the needle jet absent limitation by the tapered jet needle).
Pods are typically more difficult to tune (than the stock air box) over the entire range of carb operation.
Thanks, very interesting about transition from needle to main.