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Someone feel free to correct me if im wrong, but it was in the name of fuel efficient and power output to use a vac advance. The issue that I see is that it works in tandem with an electronic ignition unit thats a little touchy and you may suffer poor performance and fuel economy with it capped.
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1979 XS1100F "Roxy" (my first bike
) - '91 Suzuki GSX1100 Fairing, BMW bags, Cheap ABS Trunk, aftermarket cruiser seat, MAC 4-2 exhaust, Heavy Duty folding kickstart, XS11 Special signals and gauges, Blade Fuse Conversion, Dynacoil Greens w/ ballast bypass, SS brake lines -
Vacuum Advance
It's there for a reason. Engine needs a total number degrees of timing advance. If you disengage the vacuum advance, you will retarded the timing. This can cause mechanical problems to the engine. Don't do it.1981 XS1100H Venturer
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MikeComment
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The timing advance is controlled by the TCI starting in '81, the 78-80 models have a mechanical timing advance behind the timing plate, the TCI has nothing to do with it.2H7 (79) owned since '89
3H3 owned since '06
07 Triumph Tiger 1050
"If it ain't broke, modify it"
☮Comment
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So my understanding at this point is that there are two ways the timing is advanced. One is engine speed - activated by the "centrifugal advance" behind the plate and the other is "vacuum advance" for low-speed throttle response maybe? To bad Yamaha didn't get this issue straightened out for the earlier models. Whipping wires around to perform fast mechanical stunts is not a good approach. Arrrr Matys.....Comment
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