Crazy vacuum gauge fluctuations at idle

blaketots

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Hey there! Another post:

Vacuum gauges are giving me crazy readings at idle. The needles get steadier as I raise the RPMs but still fluctuate, just at a smaller increment (~2 in). Diagrams haven't yet described my exact problem. What do y'all think? Also, getting white smoke out of my right side exhaust. Recently learned my mufflers are not stock.
Changes to the engine recently:

New valve steam seals
New head gasket
Thrice cleaned carbs
Adjusted valves
New points gapped
Statically timed
New spark plug boots

My last compression test was good.

Thanks!
 
Nah, means the gauge is good.

Engines that small and few in cylinders will not make an even vacuum, the events are too few and too weak to pull down the vacuum to a constant, unlike huge car engines. Smaller makes for spikes with no holding up, the vacuum drops off before the next cylinder can input to help it stay up. Even worse on the oddfire engines these are, the huge lag in relative time before the intake events happen.

Restrictor(s) will likely make it better.
 
They should have thumb screws between the bike and gauges. I never like those types as they never seemed to be very accurate. A manometer I feel is a much better option and can be made for a few bucks. I use a set of mercury stix. These are very accurate but hard to find now a days.
 
X2 on the CarbStix. I have one laying around too, you have to be careful storing it to preserve the mercury, just try getting that nowadays, impossible.

The gauge stuff is erroneous, there is no way to make sure they are dead even, you screw the screws to even them up but that means nothing. The CarbStix thing in opposition to that self adjusts on the fly, the outputs all work against each other to be inherently in balance.
 
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