Mikuni VM 33 Carbs

They don't leak any worse than the 26's. Syncing them is no problem and I can and will do it. Mikuni calls for 1/2-3/4 turn. The air screws have a hole in them. Mine were soldered shut. I'm going to buy two new ones to replace the ones Snake munged up.
Steve

I run them on my elr some times and no problems bu tits bored and head work. crh

swest wrote: They don't leak any worse than the 26's. Syncing them is no problem and I can and will do it. Mikuni calls for 1/2-3/4 turn. The air screws have a hole in them. Mine were soldered shut. I'm going to buy two new ones to replace the ones Snake munged up.
Steve

Please briefly explain the synching process for VM33's. I have a Carbtune four-column unit, which I rather enjoy using on my BS34's.
Is the process as simple with Smoothbores or RS Flatslide models?
:lol:

Mine have vacuum ports though poorly done. :dry: You take the tops off and sync them by the lock nut and screw. #3 is fixed, that's the lead carb. I will get the levels as even as possible, blip the throttle adjust them again until they won't change. They're easier to sync than my 28's were. I changed the needle setting so I didn't bother syncing them until I knew I would leave them that way. I'll be doing it soon and will record the process.
Steve

swest wrote: Mine have vacuum ports though poorly done. :dry: You take the tops off and sync them by the lock nut and screw. #3 is fixed, that's the lead carb. I will get the levels as even as possible, blip the throttle adjust them again until they won't change. They're easier to sync than my 28's were. I changed the needle setting so I didn't bother syncing them until I knew I would leave them that way. I'll be doing it soon and will record the process.
Steve

Poorly done vacuum ports...? On the carbs from the factory, right?

No, the PO Snake AKA Shark was a moron. They don't come with ports from the factory. :dry:
Steve

swest wrote: No, the PO Snake AKA Shark was a moron. They don't come with ports from the factory. :dry:
Steve

Really, no factory supplied vacuum ports to attach synch hoses to, ok...what? :ohmy:
You got to be kidding. :dry: :evil:

I'll take a pic in the morning. You'll laugh. :huh:
Steve

With reference to vacuum sync for Mikuni 33 smoothbore carbs,

wiredgeorge wrote: Don't see a reason why you couldn't drill/tap intake runners. I have installed vacuum spigots from an old set of carb holders into a set of larger carb holders. It is kind of a pain to get them out of the old rubber but it can be done. If you drill/tap, you will have to use adapters to do the sync but if you modify the rubber carb holder, you can just shove the hoses from the manometer onto the vacuum fittings you installed.

Per Sudco:



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, when a "running sync" with manometer or vacuum gauges might be thereafter performed, Sudco says 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).

However, the stock Mikuni carbs with manual slides and side-located pilot air screws would be expected to have the same "air leak" with their caps removed, as noted by Sudco. Moreover, 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.

Am thinking most smoothbore tuners, including wiredgeorge, perform both bench sync and running sync, the same as for stock manual slide 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 top caps are replaced.

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 sync 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 adustment 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.

Good Fortune!

Never had a problem doing it plus I've dialed out a stumble this way.
Steve

Thanks again, Patton :kiss: :pinch:

swest wrote: Never had a problem doing it plus I've dialed out a stumble this way.
Steve

Keep them suggestions coming Steve! :woohoo: