compression

Hi mate. yes cold engine throttle wide open. 70 to 75 psi on all pots.

cheers scotch. engine sounds smooth no rattles. doing the carbs as been in storage though. some smoke on cold start but nothing to really worry about.

Have you checked valve lash is in spec? Tight valves will cause low compression.

strate6 wrote: We have very old low compression engines in the Z1300 (as most were with 1970's technology engines),.

Seems to me the 1300 motors were relatively high compression (at least for the day) at 10:1

I googled low compression on Z1300 and your post came up. Hope you don’t mind me jumping on.
ive got 95 to 100 psi across all 6. Starts great, doesn’t smoke. Apart from the gauge saying so, there are no indications that it has low compression although it is below specification. Was going to go into the engine and have a look, but hesitant while it runs so well. 

Have you any developments since you last posted?

Your indication could be a fault of your gauge. One of the least known issues with compression gauges is the Schrader valves. If by chance you or someone else changed out the valve with a new one and didn't  buy one specifically for a compression gauge, then likely your gauge will read between 10 - 15 psi less than it should. Schrader valves for compression gauges have a very light spring compared to a Schrader valve for a tire, and the cost for the special Schrader valve is probably around $10 cdn now. I bought one aboutv8 years ago and it was $8 back then Schrader valves for tires are around $1 each.

Food for thought.

KB