KZ650 float settings and tuning problems

anyone?

Really need help with this. Here is the diagram of what I'm talking about.

Post edited by: jccwall, at: 2007/11/04 23:55

wiredgeorge wrote:

You need to use #110 mains, jet needle clipped to 4th slot (if slotted) and #17.5 pilot jets.

The pilot jets in the '79 carb are stamped "15". The pilot jets in the '81 carbs are stamped "51". That can't be right, can it? The '81 pilot jets are clearly larger than the '79s, but, that would seem to be a huge difference, wouldn't it?

The main jets on both the '79 and '81 carbs are stamped "5CL30". I see no other markings. How do you tell the sizes?

Also, what is a good source for jets? I see main jets on Z-1 Enterprises.com, but, don't see pilot jets. I looked for a dyna jet kit there, but didn't see it.

Post edited by: jccwall, at: 2007/11/05 04:00

The pilot jets in the '79 carb are stamped "15". The pilot jets in the '81 carbs are stamped "51". That can't be right, can it? The '81 pilot jets are clearly larger than the '79s, but, that would seem to be a huge difference, wouldn't it?

---both sets of pilot jets are #15... you were looking at one upside down in all liklihood. I think I have already mentioned jetting that I would use.



The main jets on both the '79 and '81 carbs are stamped "5CL30". I see no other markings. How do you tell the sizes?

---Those are not main jets; those are your jet needles.



Also, what is a good source for jets? I see main jets on Z-1 Enterprises.com, but, don't see pilot jets. I looked for a dyna jet kit there, but didn't see it.

---Z1Enterprises.com can supply you with both the main and pilot jets... the pilot jets are VM22/210 Mikuni type.

del

OK,
17.5 pilot jets and 110 main jets installed as per wiredgeorge's recommendation.

Dyna Green coils and Dyna S electronic ignition installed.

Set floats and air bleeds per wiredgeorge's recommendations.

The change is unbelievable.

Bike starts perfectly and idles at 1000-1100 rpm.

You can pull off from a standing start, beginning to engage the clutch at idle, and only give it the slightest bit of throttle and it pulls away smoothly.

Even when you lug it in any gear and roll on the throttle rather than downshit, it pulls steadily, with no hesitation or bogging.

Previously, at full throttle, it was backfiring terribly at 5000+ rpm, now it pulls all the way up to redline, although, it does seem a little low on power.

There's only one real issue. It's "popping".

I don't mean popping when you let off the gas, I mean popping at idle, popping at just a little bit of throttle, and popping at a steady 40mph cruise at 3000 rpm.

It's not a miss or a backfire, the engine is running smoothly, it just pops. .

The only negative to the way it's running is popping related. If you're rolling slowly in gear, with just a touch of throttle, the popping turns into "loading up", where the popping escalates to where it stops pulling. It clears right up as soon as you roll on the throttle, though, where previously, when it loaded up, all you could do was wait it out and hope the truck barrelling down on you has good brakes.

I don't think the popping has anything to do with the coils or dyna s ignition, as it did it (only much worse)before they were installed.

Now, wiredgeorge's jetting suggestions were for the bike with pods and a 4-1, but, this bike also currently has no baffle, which, i'm sure, would leave it still lean.

The baffle is ordered, although the owner would prefer to leave it unbaffled. I was thinking the popping might be related to the bafle being gone, and was going to just wait till it comes in, but, I ran across a guy at the parts store yesterday on a Z1 with a 4-1 and no baffle. He said it runs perfectly, with no popping.

Is the popping jetting related, or, is there something else I need to look at? The only thing I can think of that might be less than optimal is that the carbs are only bench synced, I don't have the tool to do a vacuum sync. Could this be it?

Post edited by: jccwall, at: 2007/11/20 11:15

Non-baffled exhaust systems will backfire on decelleration. You can attempt to adjust the pilot mixture (as this is the circuit affecting the backfiring (throttle is closed) or install some baffles. I suspect that if you went to #20 pilot jets, the plugs would start sooting at idle.

wiredgeorge wrote:

Non-baffled exhaust systems will backfire on decelleration. You can attempt to adjust the pilot mixture (as this is the circuit affecting the backfiring (throttle is closed) or install some baffles. I suspect that if you went to #20 pilot jets, the plugs would start sooting at idle.

what do you think popping at idle, idle-1/4 throttle, and cruising at 3000 rpm might be, then? The bike definitely backfires on deceleration, but, the popping i'm talking about is at idle, at cruise, and under low throttle, mild acceleration.

Post edited by: jccwall, at: 2007/11/20 18:23

I might have missed it while reading through this thread but have you synced the carbs?

only bench synched. dont have the tool to vacuum sync them.
jim

Double check for vacuum leaks at the manifolds, and any vacuum hoses by spraying them with carb cleaner.
You can do a simple sync test with one vacuum gauge and a delay valve. The delay valve will stop the gauge from bouncing and making the reading impossible. You want the side of the valve with no resistance pointing toward the head. You can tell which end has no resistance by sucking on each end of it and feeling which one does not have any resistance.
Then take a vacuum reading on each of the cylinders and see how well the match.
A low reading will mean that carb is open wider and a high reading will mean it is closed more. Adjust the one with the widest variance up or down a tad and recheck tham all again. Like I said, it will take a while but it's possible to do it that way.
Also, do you still have the emission hoses still hooked up to the valve cover the way they were from the factory, if that system isn't working right it will cause popping.

Slide actuators are bolted to the common throttle rod. Unfortunately, when you change the slide height with one carb in a mechanical slide system, the other three slides are affected since they are all linked by the rod. Synchronizing 100s of set of carbs has taught me this lesson. I would suggest purchase of the correct tool; a manometer with four gauges.

There are many reasons for popping... ignition timing, valve clearance issues, poor compression, air leaks at the exhaust gasket location and ANY intake location, etc.