Stumped! Carbs valves electrical or what?

I use grease. Have for years. Mine are the originals.
Steve

KZB2 650 wrote: . . .
Hey Patton school us on the air screw and sync too will ya please .... it seems like I remember you saying it should be under 1 turn maybe 1/4 or 1/2 turn out from closed way back and also they should only be bench sync'd cause with the tops off and adjusting them with a sync gauges they will be off as the slides leak air and throw you off.......... I will admit the 2 times I used a ground rod to bench shim them they were closer than I ever had them with the mercury sync.

To make info about syncing smoothbore carbs easier to find, I created a separate thread entitled
Sync smoothbore carbs.
Here's the link:
www.kzrider.com/forum/3-carburetor/59979...othbore-carbs#691778

Here's the initial post:

Patton wrote: Sudco recommends only mechanical sync for smoothbore carbs.

Such mechanical sync is also known as bench sync, where the carb assembly has been removed from the engine and is on the work bench with the top caps removed to allow access to the throttle slide adjustments in each carb.

After the bench sync, would normally expect to do a "running sync" with manometer or vacuum gauges, but Sudco says among other reasons that the detached caps allow air leaks which adversely impact a "running sync."

In summary, Sudco says to carefully bench sync, followed by pilot air screw tuning of the idle circuits with the carbs fully assembled (i.e., caps attached).

Where a manometer or vacuum gauges are available, I suppose the manometer or gauges could be attached and watched while doing the pilot air screw tuning (caps attached).

The stock Mikuni carbs with side-located pilot air screws would be expected to have the same "air leak" as noted by Sudco with their caps removed. However, the Kawasaki FSM details the procedure for both bench sync (basically same as the mechanical sync described by Sudco), followed by a running sync with caps removed and manometer or vacuum gauges attached.

I'm as yet unconvinced why smoothbores should only be bench synced without the same later running sync used on stock Mikuni's as provided in the FSM. And I have long enjoyed success in syncing smoothbores by following the FSM stock carb sync procedure for Mikuni mechanical throttle slide carbs. The dreaded "air leaks" with caps removed hasn't been an issue. And in any event, running sync may be easily verified by reading the manometer or vacuum gauges after the caps are replaced and vacuum plugs reinstalled.

Let's say that bench sync has been done, and the carb assembly is now reattached to the engine, and the carb caps are off, and manometer or vacuum gauges are attached, and engine is idling, and synch screws have been adjusted to provide the best equal vacuums in all carbs, and the slide adjustments have been locked. Next, turn off the engine, remove the manometer or vacuum gauges, and replace the caps. Then re-start the engine and proceed with final fine tuning of the pilot air screws.

Remember to have a fan blowing on the engine to keep it from over-heating while the engine is at idle rpm during the running sync process and pilot screw fine tuning adjustments.

Here's a tip about bench sync that might not be mentioned in the FSM.
When setting the slides to equal heights (with paper clip, drill bit, wire, or whatever), be sure to have the idle adjustment screw threads in approximate mid-position or at least in a position to assure that the slides may be lowered during the running sync. Neglecting this step may result in being unable to sufficiently lower the idle rpm. For example, when fine tuning the pilot air screws gets the idle rpm too high, it's important to have some threads remaining on the idle adjustment screw in order to reduce the idle speed.

wiredgeorge wrote: The VM family of carburetors including the smoothbores already mention have mechanical slides. That is, the throttle cable pulls up on the throttle bellcrank which is bolted to the slide rod as are all four carb slide mechanisms. The tops being on or off make absolutely NO difference to the function of the slides... You can run the bike without the tops on any VM carb assembly including smoothbores. . . .

www.kzrider.com/forum/3-carburetor/85578...-carb-sync-how#85676

wiredgeorge wrote: Synchronizing a carburetor assembly means all four slides open at the same time. There is no "main slide" only "a slide" in each carburetor. The smoothbores, like all VM series carburetors are happiest when synchronized while the bike is running using a manometer. If you are trying to bench synchronize these carburetors, bend back the holding tab on the hex head slotted screws in front of the sync screws and loosen the hex head slotted screws so the sync mechanism is free to move. Then loosen the locknut and adjust the slide height using the sync screws. There is probably a spec somewhere for setting these where they are barely open... like .5mm or something along those lines but I like to use long heavy-duty paper clips under each slide and open the slides with the idle adjust knob and then close it down on the paper clips. Then I like to adjust the slide height so that when pulling out a paper clip, each has the same feel when pulled. This adjusts the slide height at about 1mm but the slide can be closed again when the paper clips are out of the way. You can use bigger tools to set the height up to a point. At that point, the slides will be adjusted too high across the board and the idle adjust knob won't be able to shut the slides sufficiently to get idle down.

www.kzrider.com/forum/3-carburetor/920-v...ncronizing-hight#983

If only bench synced and pilot screws tuned with caps attached -- as recommended by Sudco -- and manometer or vac gauges readings are acceptable with a stable idle, I would leave well enough alone and not attempt to further adjust slide heights with caps removed. . . .

Good Fortune!

I agree. Each cylinder will require a different setting. Vacuum can be higher or lower accordingly. If a slide is worn out, chances are the bore is too so that carb is junk. I have "bench synced" carbs, put them on the bike and it stumbles something awful. It will only clear up with a running sync and purr like a kitten.
Steve

I did my compression test today. getting about 155 in every cylinder except 3 that one maxes out at 140. I put a bit of oil in that cylinder and got 170 out of it! Does this indicate that the rings are pretty beat in that cylinder? The bike sat for 25 years before I revived it but I've probably put 100 miles on it since then. could they just be sticking?

It could mean condensation got into that cylinder. 140 isn't too bad. I'd run it and see if it gets better. Did you check your valves?
Steve

Dirtyhands wrote: ... I put a bit of oil in that cylinder and got 170 out of it! Does this indicate that the rings are pretty beat in that cylinder? .....

Not necessarily. Take a look at the link below. Adding oil will always make the compression readings go up even in a perfect engine. Ed

www.kzrider.com/forum/2-engine/597329-major-problem#663128

Haven't checked the valves yet. I'm going to give the carbs another good going over and bench sync them first.

Started taking the carbs apart and saw I was on the second notch up from the bottom on my needle setting and not the middle. I moved it there after switching from the previous owners jetting o 135 main and 20 pilot to my current jetting of 120 main and 25 pilot. Should I be in the middle? The setting I am running now was what was recommended to me in this threadhttp://kzrider.com/forum/3-carburetor/599241-vm29-jetting-for-738cc-performance-bike

Look, before you go to the carbs, do the maintenance first. If you get it running good with tight valves and burn a few, where will you be?
Been there.
Steve

My cams spec say running lift should be at .006 inches or .153mm
I've checked the valves and these are my numbers
#1 (Cyl#1 Exhaust) .005 inch (.127mm)
#2 (Cyl#2 Exhaust) .006 inch (.152mm)
#3 (Cyl#3 Exhaust) .006 inch (.152mm)
#4 (cyl#4 Exhaust) .005 inch (.127mm)
#5 (Cyl#1 intake) .005 inch (.127mm)
#6 (Cyl#2 intake) .006 inch (.152mm)
#7 (Cyl#3 intake) .005 inch (.127mm)
#8 (Cyl#4 intake) .004 inch (.102mm)

will going a shim size smaller in #8 help . As for the others are the fine where they are or is it better to be over rather than under the specified lift?

I called the Cam people and found out that the preferred lift is more like between .006inch and .007inch (.152mm - .178mm) She also Said these cams also don't like to be idled low (under 1800rpm) I'm going to change the shims. I've simultaneously been ultrasonic dipping and blowing out the carb bodies so hopefully one of these measures sets things right.

What kind of cams do you have?
Steve