'77 kz1000 Carb sync. Cylinder #2 unsyncable.

I recently rebuilt the and cleaned the carbs on my '77 kz1000 A1. Installed pods. Still has factory 4 into 2 exhaust. Upped the mains from 105 to 107.5. Pilot jets are the 15.

Runs fine. Went to sync carbs. Readings
Cylinder#1- 23 cmHg
Cylinder#2-21 cmHg
Cylinder#3-10 cmHg
Cylinder#4-21 cmHg

Factory manual says to set vacuum between 20-28 cmHg. But there isn't enough screw to adjust the one carb. You guys think its a vacuum leak or valve lash on the one cylinder or what??

Did you bench synch the carbs? That's when you get all the slides even in height with each other.

Is it #2 or #3 that wont synch up? From your numbers its #3 that has the slide too high compared to the others. Also according to my service manual the 1977 LTD (B1) has 105 mains and 15 pilots, the 1977 A1 has 107.5 mains and 17.5 pilots. With pods you will probably need more like 125-130 mains and 20+ pilots....from what I have read.....I'm on original airbox setup.

If the carbs wont bench synch look for bent/broken linkage or other mechanical problem. When I got my bike #1 would not bench synch with the other three (it was too high and out of adjustment).....turned out the little linkage plate inside the slide was bent, in effect shortening it causing the slide to be higher than it should have been.

Maybe you have something simple like that going on.

I would check for vacuum leak on the carb holders. Here's how:
www.kzrider.com/forum/3-carburetor/59338...sync-78-kz750#628442

Also, it's possible a previous owner swapped your carbs with those from a later model. If so, the #2 carb may have a vacuum port (that was used for a vacuum operated petcock) on it that is open. If it has the vacuum port it should be located near the same position as the one on e VM24SS carbs (even though they are different than your carbs) shown below. Ed

Your first mistake was installing pods. Toss them in the trash re install stock airbox.
Then
Let the good times roll


just my two cents

Installing pods will not effect synching the carbs. It looks like you do have a vacume leak on #3. Ignore the amount of vacume just get them all the same.

Don't you guys think he should pull them back off and bench sync them first? Yes, if bike still has original carb boots he has air leaks, no question. But a bench sync will get the bike running well enough to start working on chasing other problems.

Or he says its running fine....maybe start chasing other problems now and come back to sync later. The service manual gives a whole list of items to check before performing running vacuum sync. Everything from checking engine oil, spark plugs, ignition system, throttle cables, air filter, air ducts and carb linkage, compression, valve clearance, cam chain.....everything! The way I read it, vacuum sync is for when you absolutely know everything else is spot on.

When you bench sync the VM carb's remember the number two carb is the lead carb.
Set that carb first then set the rest to match.

Getting them all the same when 1 is at 10 and the other 3 in the 20's will likely be impossible :dry:
Find and fix the leak on #3 then set all 4 as close to the same and in the range specified as you can
If you can't find a leak then move on to checking for mechanical issues..... Linkage or such ... then might have to check valve clearance, I would put that at the bottom of the list though...

Definitely vacuum leak, valve adjustment, or junk in the carb.

I noticed on my VM for my 650, when I screw the 8mm head bolt down, which holds the slide mechanism to the throttle shaft, there was some play allowance when being bolted down. I found this when bench synching. One carb wouldn't close as much as the others. Loosened that bolt, rotated the slide mechanism, and retightened.

Also, pull the filters and take a look inside, does the #3 look off compared to the others? Is the pilot jet circuit clean?

There's really no need to bench synch if the bike runs, you're going to adjust them all anyways when you put your synchronizer gauges on.

Twilightoptics wrote: There's really no need to bench synch if the bike runs, you're going to adjust them all anyways when you put your synchronizer gauges on.

First the VM carb's use a tapered screw on the slide hanger
that go's in a tapered hole in the shaft there is no play when tite.

Second don't give false info. If you think there's no need to bench sync.
a set of carb's you need to learn a little more about multi carb. set up's.
Bench sync is a nechanical adjustment to set the slide's at their base setting.
Vac sync is a mean's to balance the idle air or fuel for the highest vac.
If the slide's are NOT set the same you CAN NOT balance the carb's..

Dave, I was merely giving the information that I have.

1.) The screw is shouldered, not tapered, but there is still play. It's not a near press fit. Therefore there is further adjustment or compensation that could be had if needed or like I described above.

2.) According to my FSM... vacuum synching the carbs involves adjusting the slide height screws/jam nuts. Which, IS a mechanical adjustment. If you're adjusting those to get your highest vacuum, and the bike is already assembled and in running condition... you're going to pull the carbs off to bench synch every time first? I don't think so. In addition, there is a range for vacuum and if within range, to adjust the 3 to the highest of the 4th.

The Kawasaki Service Manual does make a clear distinction between "Initial Synchronization - Mechanical" and "Fine Synchronization - Vacuum." The mechanical sync is purely a static measurement and adjustment using a wire as a gauge, but the vacuum sync is done with the engine running so it can compensate for any variances between the individual cylinders. So even though turning a screw may in general be considered a mechanical adjustment the synchronization of the carbs using vacuum gauges is not considered to be a mechanical synchronization. The manual may have done better to refer to the two adjustments as Static and Dynamic. Ed