Compression issue- Timing?

I'm looking for some suggestions: I have an 82 KZ1000LTD. I don't know much at all about the history of this bike. I want to completely restore this bike, so I started with the basics.....check compression. I found that compression was really low- say well below 90psi.all 4 cylinders. I tore down the motor- cleaned, took the valves off, cleaned and inspected them, checked the pistons, and head- everything looked and was within spec. The bike has 17k on it (so it says?)

After reinstalling the head and cams- timed it out and rechecked compression. It was worse than before 60PSI- and one cylinder 0 psi. I tore it down again and figured I better do a leak down. I found that all the cylinders were leaking at either the exhaust or the intake. I figured it was the shims- I ordered new shims= 2.30 to 2.35. I have yet to test my clearances of the valve and cam.

After re-timing and installing the new shims- compression test showed still 90psi- At this point I did a leak down test again- and found that all exhaust were leaking but very minimal- I took the cam off so all the valves were closed and did a leak down- this we most difficult to hold the pistons at TDC and put over 100PSI into the chamber- I couldn't hold it past 110PSI and figured that I had good compression on all the cylinders with good valves as well.

So, not get too long winded, I'm thinking it could be a timing issue? I have followed the manual timing which says to bring #1 and #4 to TDC with the "T" mark with the F1 & F4 set the exhaust cam with the EX arrow to the front of the bike and set the intake cam with the IN (arrow) facing the rear of the bike and then counting 44 links from the exhaust to the intake.

I did notice that when doing the leak down test, it seemed that it just wasn't timed right with the pistons being at TDC I had leaking at the exhaust, but I could turn the motor just a little and it held to past 100psi.

I'm looking for help- without writing a novel. Thanks.

When you did the compression test did you do it with the engine warm, all plugs removed, and the throttle held wide open? Ed

I can't test it warm because it's not running (yet) I didn't have all the plugs out, just loose and the carbs are not installed. Just for reference I did a compression test on my 700LTD it was well above 150PSI with the engine cold, plugs in and throttle closed. So I would think since these motors are really similar I would get compression at least over 120PSI.

menomax wrote: I did notice that when doing the leak down test, it seemed that it just wasn't timed right with the pistons being at TDC I had leaking at the exhaust, but I could turn the motor just a little and it held to past 100psi.

I believe that is correct. I think the cam lobes have some "overlap" at TDC where both valves are very slightly open. As shown above, intake opens 30 degrees before TDC and exhaust doesn't close until 30 degrees after TDC.