How much compression should my 78 KZ1000 have?

Yep, the 900/100 when cold is very low... the 650/750 seems to be higher - maybe 150... were talking good low mileage motors.

My buddys 900 after it was back from a fresh bore job = 120 cold... it runs like a scalded cat...

here's what I got.

1 152
2 142
3 140
4 150

shows the classic pattern of more wear in the center due to higher temps. I did this cold. Ran the motor about 10 sec just to circulate the oil first and then shut it off.

I'll pull top end and have a look.

Those look like pretty good numbers.... even for a 750 twin.:laugh:

Nelson wrote:

Stock internals as far as I know. My plan is to put a compression tester on each cylinder. Then hold the CV slide open with my finger and throttle open, hit the starter button and see how hi it will go. What should I get?

Per FSM for 1978 KZ1000: Standard compression is 128~156 psi; service limit is 100 psi with less than 14 psi difference between cylinders.

FWIW, 1978 KZ1000 came with 26mm Mikuni VM26SS manual slide carbs (not CV carbs).

Good Fortune!

A leakdown test would help eliminate some of the guesswork.

And as TeK9iNe suggested, assure valve clearances are within specs, this being regardless of compression test results and regardless of leakdown test results.

Good Fortune!

FWIW, 1978 KZ1000 came with 26mm Mikuni VM26SS manual slide carbs (not CV carbs).

yes I put on CVs from a 97 police bike a few yrs ago. Very nice power boost for little money! I think it even improved the mileage a little.

At this point I've decided to take off the top and see what there is to see. Then I'll decide how much money to spend.