QuestionQUESTION: 1978 Kawasaki KZ1000. I had the carbs rebuilt and cleaned up. I have them back on and have verified there are no air leaks around the carb holders. Pulled the tank, drained it and checked the filter and lines. I pulled and cleaned the petcock and it seems fine with good flow when set to pilot.
The bike runs but needs a little fine tuning. When I get on the throttle hard there is a slight hesitation and then it takes off really fast up through high speeds. Really strong.
At slow speeds with light throttle application, off choke, the bike is pretty good with some sputtering until getting to mid range. Above 25 or 30 using half open throttle there is poor performance. Lots of hesitation, sputtering, and bogging down. Applying choke helps. Crank the throttle open and it bogs and then accelerates strong.
I put in new plugs before running and upon return the plugs are black and sooty.
The bike is set up with pod air filters and aftermarket exhaust: Vance and Hines 4 into 1. The carbs are 78 VM26s using #20 pilot jets and the jet needles were clipped to 4th slot.
Any advice would be appreciated.
Thanks,
Dave
ANSWER: There are a couple of possible solutions to the problem, but they all depend on one question - have you synchronised the carbs yet? If they are not set to open at exactly the same time when the throttle is twisted, you will be forever chasing your tail for a solution.
So assuming that you have already done the synch, there is still one problem that isn't going to make it any easier to fix. Multi-carbed motors are a real pain to set up if they are using individual air filters. Carbs work best when they have a stable, consistent air supply to draw upon, which is why your bike originally came fitted with a large airbox containing one air filter. By removing and replacing it with individual filters - even if they are low restriction, high flow - each carb will draw a different amount of air and require a different setup. If you were setting up a drag bike, then individual filters would be beneficial because of the huge amounts of air needed at maximum rpm. But for street applications, really, pod filters don't do much more than make the bike look cool. So if at all possible, it would make your life easier to install the original airbox with a low restriction filter replacement, like what is available from K&N.
Anyway, that's enough preaching. Aside from the above, the problem seems to me to be caused by the carbs running too rich in the low to midrange settings. You have compensated for high speed operation by lifting the jet needles, but for lower speeds I think you need to experiment with different slow jet sizes. With a low restriction exhaust like yours, I would suggest starting with two sizes up from the stock jets and see how that works.
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QUESTION: ...I think you need to experiment with different slow jet sizes. With a low restriction exhaust like yours, I would suggest starting with two sizes up from the stock jets and see how that works...
When you say 2 sizes up, what sizes would you suggest?
AnswerTwo sizes up from whatever size the stock jets were... and that info, unfortunately, I do not have. You can probably find that answer on the Kawasaki Owners Club forum at: http://kawasakiownersclub.com/
You can find various jet sizes for your bike at a site like this one: http://www.crc2onlinecatalog.com/misc_carb_parts.htm
Hope this helps!
