thought i would share the drastic difference between a quality compression gauge vs others on the market.
the bike:
98 banshee
fresh 421 assassin low ports
33mm pwk's
vf4 reeds
cpi inframe
noss head 18cc domes
+4 timing
the gauges:
ac delco from orielly. 24.99
craftsman from sears. 47.99
snap-on eepv500. 234.99
current elevation 6500ft.
where i ride 7000ft.
all tests were done one after another on an engine that ran for about 5 minutes to pull it out of the trailer to garage, both plugs out, throttle WO, kicked until gauge stopped climbing.
estimated compression from driveline 170psi for 110
First test was with the ac delco: about 15 kicks until gauge stopped right on 140 psi
second test was with the craftsman: about 15 kicks until gauge stopped at 155 psi
third test was with the snap-on: about 15 kicks until gauge stopped at 165 psi
the difference concerns me a little due to the fact that if i would have ran fuel appropriate for 140 psi i would have probably had serious detonation and could have hurt motor easily.
i am sure this has been posted before but just thought it would help out others. i didnt have a snapon, but i easily found one to borrow for an afternoon. if you are in a similar position to what i was, take a day to find someone to help you out with a good compression gauge.