79 kz1000 st no compression on all 4 cylinders

I know this is a necro bump, but I have a 77 kz1000A with 21k miles. I am smoking from 4th cylinder and have deposit on cyl 4 plug so i checked the compression to rule out rings. While i was at it I checked cyl 1 that appears to run well and has good plug chop. Both cylinder 1 and 4 were between 180-182 psi. Is that possible on a stock bike with that many miles ? Those are new out of factory compression numbers. Any ideas ? Perhaps a faulty gauge ? At least they are consistent, right.

Standard compression is 128~156 psi.
Higher psi might be carbon build-up on the piston and/or cylinder head.

Heavy oil burning in a cylinder could result from a broken oil ring or worn valve seals, which would not necessarily have any effect on compression figures.

Good Fortune!