It may be noth'n, but I disconnect the coils and pull both plugs to check compression. It lets the starter crank a bit better and - real or imagined - get a better reading. Disconnect the fittings on the gauge and hose the inside with carb cleaner to degrease the little valves and tube. Try it out again. My 2¢
Custom Top Brace: http://www.pbase.com/toastertan/top_braces
72 R75/5 Toaster ~ 91 R100GS-PD ~ 04 R1150RT ~ 80 CBX-SuperSport ~ Scratch-build Bobber project using 1203cc Thunderbolt engine.