motion pro sync tool,

the FSM give readings for vacuum gauges, but i have the motion Pro sync tool (which has no numbers just marks), anybody know the preferred reading or level for VM 28's on Z1 900 for this tool???

I just use the gauges to make sure readings are the same. it also helps to make sure valves are adjusted properly and no vacuum leaks on the motor.also check and verify ignition timing to make sure its correct,at that point you have done everything to make sure of a good accurate carb sync with the engine present condition. any other problems require major engine maint such as valve job, piston rings etc.

ok thanx

DFIGPZ wrote:

I just use the gauges to make sure readings are the same. it also helps to make sure valves are adjusted properly and no vacuum leaks on the motor.also check and verify ignition timing to make sure its correct,at that point you have done everything to make sure of a good accurate carb sync with the engine present condition. any other problems require major engine maint such as valve job, piston rings etc.

X2:)

figure out which carb has the highest reading and then set the other carbs to it the most important bit of info is get them even. also when you make an adjustment blip the throttle abit to settle things down

timebomb33 wrote:

figure out which carb has the highest reading and then set the other carbs to it the most important bit of info is get them even. also when you make an adjustment blip the throttle abit to settle things down

wouldnt you adjust them all to the master carb.
dont VM 28's have a master?

Timebomb33 raises an interesting question - would an engine with carbs synch'ed to the lowest vacuum reading run the same as one synch'ed to the highest?

(Ooops, I should have said the same engine synch'ed each way, doh!)

You dont have that option, if u have a master carb.
it makes no dif.
all u are doing is adjusting the slide height to get the same amount of vacuum, then u will adjust all carb slides together, up or down, with the linkage idle screw to achieve the proper rpm.

I do use carb sync tools, but I'm very careful about how much I adjust the carbs AFTER I've synced the carbs on the workbench.

If you are dealing with an old set of carbs, the sync at idle can be influenced by wear in the carb. Air can leak past slides and idle passageways may not flow fuel or air the same as when new due to corrosion or gasoline deposits.

With Z1 and fully mechanical carbs (not a CV carb). I sync the slide heights with a thin round piece of metal (actually a partially unwound paperclip). Then when I make an vacuum adjustments I only tweak any one adjuster a very small amount (1/4 turn or less).

I adjust the air screws/fuel screws to help sync the idle more than any slide linkage adjustment

While a super smooth idle is nice, it's more important to have the slides fully sync'd when the needle / needle jet come into play in the mid range.

most older slide carbs don't have a locked in place carb you can raise and lower the slide heights individually cv carbs on the other hand do use a locked carb usally number 3. so you have to tune the other carbs to that one

What's a "master carb?" Ed

the carb that the other 3 are sync'd to.