VM26 out of range for synch

i have now bought some airvalves and placed them on the lousy motion pro carbtool. the reason for that is that without them all the fluid is sucked
out of the "tool". The valves works and can be adjusted to decrease the vacuum .So today i went to my favorite wrencingspot outdoors and was going to do a carbsynch.  It did not go well because i found that the screws for adjusting is out of range.Is that a sign that the jetneedle is sitting to high ? And one more thing  im not familiar with these carbs is there no "master carb" on vm26 How can i fix them so i can use the adjustment screws? i benchsyncked them last winter when overhauled and used 0.7mm drillbit.
I forgot to mention that 2 of the carbs pull way more vacuum and i can not fix that

You are correct that the VM slide carbs have no master.
You just need to set all the slide adjusters mid way on their threads so you have equal adjustment either way.
Then bench sync them by simply setting the slides all to the same height .
Once done it should take very little adjustment to get them all pulling the same vac reading.
A cause for a cylinder or two to be way off is likely due to air leaks at the carbs rubber manifolds unless you have other mechanical issues such as poorly seating valves or some cylinders with substantially lower compression etc.

zed1015 wrote:

You are correct that the VM slide carbs have no master.
You just need to set all the slide adjusters mid way on their threads so you have equal adjustment either way.
Then bench sync them by simply setting the slides all to the same height .
Once done it should take very little adjustment to get them all pulling the same vac reading.
A cause for a cylinder or two to be way off is likely due to air leaks at the carbs rubber manifolds unless you have other mechanical issues such as poorly seating valves or some cylinders with substantially lower compression etc.


 

Okay thanks .I checked the slides with a drillbit last winter .but since they was 0.7mm i did not take a look at the adjustment screws on the top.
Today i was thinking that i may losen all the throttle linkage bolts to get all 4 slides down ,but the rod for the slidelifters may have premade notch/holes ?
So i did not mess with the throttlelinkage bolts. 
I will check if there is a false air leak from the boots i had no starterfluid with me today so will check that later.The boots on both sides are fairly new and soft.
The compression i checked a couple of weeks ago when engine had done 200 miles .The comp was good 140-150psi cold engine.Also checked valves 2 times and they are in spec
I have been trying to tune the engine mixturescrews many times last weeks and the plugs are now ok ,but on the 2 cyl that is pulling high vacuum the plugs have been lean so i have done many adjustments on the mixturescrews to get them run more rich
I think maybe i have not pushed the carbrack all way into the boots on the cyl side.I will spray some strarterfluid  and se if it reacts.
The reason i want to synch is that the engine vibrates at 2700 rpm and it feels like the carbs are out of synch.

Also, the valves you installed are another variable. To be sure they are not giving you different readings, I think it would be best to connect all four lines to a single vacuum source and adjust the valves so that each tube reads the same. Then do not touch the valves again.

TexasKZ wrote:

Also, the valves you installed are another variable. To be sure they are not giving you different readings, I think it would be best to connect all four lines to a single vacuum source and adjust the valves so that each tube reads the same. Then do not touch the valves again.

 

Yes that is how i have synched the tool before the tool has a 5 pin connector and the fifth pin is for the hose to synch the tool.but today i just connected one hose to sync the tool. and adjusted the airvalve so the fluid stopped rising so it did not get sucked out.Then i moved the hose to the other carbs and checked if they was at same level .I think i will try the way you described using the airvalves to synch the tool

I would do a static referenz sync first. Adjust the idle positon high of the sliders to fit a 3 mm drill in all carbs from the cab outlet side.
Turn the oulet of the carb rack into the 6 o´clock position. Then adjust the sync screws until all drill bits fall out at the same slider positon.
For butterfly carbs i use a 0,10 mm feeler gauge the set static sync.

Rolf i've got the exact same carb stick and have never had to modify it. Are you adjusting the individual slotted screws per tube correctly during set-up? Also slamming the throttle closed after revving it up will be a no-no.

Scirocco wrote:

I would do a static referenz sync first. Adjust the idle positon high of the sliders to fit a 3 mm drill in all carbs from the cab outlet side.
Turn the oulet of the carb rack into the 6 o´clock position. Then adjust the sync screws until all drill bits fall out at the same slider positon.
For butterfly carbs i use a 0,10 mm feeler gauge the set static sync.


 

I did also use feeler gauge blade when rebulit the carbs this winter.I did not do anything to the settings i just checked with feelerblade before i teared them down and checked after rebuild.The strange thing is what i found today the adjusting screw on carb 3 was not same height as the other 3 carbs. not sure what has happend.

asphalt900 wrote:

Rolf i've got the exact same carb stick and have never had to modify it. Are you adjusting the individual slotted screws per tube correctly during set-up? Also slamming the throttle closed after revving it up will be a no-no.
 

ok today i think i found the reason se next post.

Today i did a new attemt to get the carbs syncronized.  Today i had more tools .First checked if there was any airleak at the rubber boots on both sides of the carbs sprayed with starter fluid around the boots.No difference in idle speed so that was good no leaks. Then checked the compression to se if valves are okay.
The engine has now run about 450 miles since rebuild so it is finished run in  and rings are seated. The compression was good cyl 1 has 160 psi cyl 2 3 4 has 150 psi hot engine.
Then removed the lids on the carbs .Last time i did not remove lid on cyl 2 and 3 because i did not have a long enough screwdriwer and i desided to quit because i found it was not possible to adjust the cyl 1 carb because the adjusting screw was out of range.I mean it was not possible to tighten / lock the nut and even if it had beed able to lock the adjuster  it was still to much vacuum when screw was fully out.

Today when i took off the lids on 2 and 3 carbs i could see that the adjuster screw on carb 3 was alot deeper screwed inward.So i losend all  4 screws all way out and put them with the locknut about same height so i could have more range to adjust and get them locked.
The motion pro tool "worked" better now exept that one of the straws was not working . so after synch the cyl 1 2 and 4 .i put on the rubberboot on the vacuumport on 4 and moved the hose to cyl 3 and adjusted the screws so all 4 carbs draw same vacuum. did many adjustments on the idle screw as well
the idle screw has to be unscrewed to get the carb 3 lid off but that is easy and just put the idle screw back in again when synching. Then did a short ride and the vibration around 2700rpm is gone and engine feels smooth,but now the engine bogged/burped a little when opening throttle fast so will have to adjust more on the mixture screws again and again and again .This green lady  really want things her way haha.

Great to hear, explains a lot. Because those aren't "really" KZ900 carbs, did someone slip in a KZ650 adjuster? The 650's looked/worked the same but are shorter. 

asphalt900 wrote:

Great to hear, explains a lot. Because those aren't "really" KZ900 carbs, did someone slip in a KZ650 adjuster? The 650's looked/worked the same but are shorter. 

 

When i bought the bike in august last year i was told that it had kz1000 carbs.
When i look in the workshop manual now they look similar to 1976 kz900 carbs there are several different carbs in the manual so not sure