Vacuum

[donebysunday]

gauges that came with a bike I bought are not zeroed. I don't see any way to zero them so they may go bye bye.
Anyone know how to fix these please ?
Or need them for parts ?
Thanks, Done

[BA80]

If they are regular analog gauges (like I prefer) there is an adjustment screw on the back of each guage. Tee them all together and use a single vacuum source to equalize them all.

The needles may not sit exactly on 0 when at rest but that really doesn't matter. It really doesn't matter if the read accurate numbers either, just that they all read the same when in use teed together.

[DiverRay]

I have a "cheap" set, and no, they are NOT in sync, and no adjustment. I "T" the lines together and check them with my vacuum pump. I know what they all read at 20, so I can still get the carbs REALLY close.

[donebysunday]

Thanks

guys !
I thought I was having a brain fart and that sure could be the case. I don't remember ever working with gauges like this I always use Carb Styx or my home made version. I bought my carb styx back in 1980 for my SF along with 8lbs of mercury and I've just used the last of the 8lbs of mercury.

[motoman]

Just remember, using vacuum gauges be sure and insert a restrictor(pilot jet,etc.) in hose end that attaches to vacuum gauge, not end that attaches to vacuum port.

[donebysunday]

Thanks guys !
I found the adjustment screw on the face of the gauges, unscrew the sight glass and turn the screw. I did get them zeroed and behold they now match at rest.

[BA80]

Thanks guys !
I found the adjustment screw on the face of the gauges, unscrew the sight glass and turn the screw. I did get them zeroed and behold they now match at rest.

But, do they read the same when teed together under a single vacuum source.

[DiverRay]

donebysundy,
At rest is one thing, but they MUST be the same at 15", or 20"!! Sometimes they will NOT all be the same at rest because they ARE adjusted at 20" from the factory! You NEED to use a pump with all 4 connected at once to VERIFY they are the same in the range they will be used. If not, the carbs will never be in sync.