g1 compression

[rabbitt_hunter02]

how much compression should my g1 be holding? Also, how big of a job is changing the crank seals? thanks for any advice.

[smallblock450sl]

Originally Posted by rabbitt_hunter02

how much compression should my g1 be holding? Also, how big of a job is changing the crank seals? thanks for any advice.

Do you know the model/serial# of your car ? All G1's (EXCEPT) 1982/J17, would have 120 lbs-good compression at "wide open throttle" and a minimum of 100 Lbs. In 1982 Yamaha tried a lower compression engine, mainly reeds/manifold/carb...and should read 110 to minimum of 90 lbs. You can try the old trick of adding oil to the cylinder and see if compression gets higher...If so bad rings/piston or cylinder lining. Search "crank seals" and you will find many posts. Remember..you need "ring compression and crank case pressure (on a 2 cycle) to "suck the gas/oil thru the carb/reeeds/piston ports and cylinder ports. Let us know what you find. Good luck Dave