TOPIC:

So. I'm embarrassed. I've done this 100 times on my 82, but this is my 81 parts motor. I swapped my shims around to get proper clearances. They were all very snug before, but produces 130's for compression. I got it back together, and now I'm pushing 105 or so psi.

I had some issues getting the cams timed. Set the motor to 14 tdc. Lined the ex mark up with the head and made sure chain was tight. Slipped the intake in and got its mark flush. Counted the links and got that straight. But, the ex Mark on the exhaust was a little higher than the head, which I remember was the case on my other bike. The intake mark is a hair below the head but close to flush. Links match the oem manual exactly. Tried to see if I couldn't get the ex Mark to better line up but couldn't. I attached a pic.

Anyway if I'm off just a hair, will that cause a drop in compression like that? Also, I have the carbs and exhaust off, along w smog device, but I wouldn't think that would make a difference.

How many miles on that chain? Did you try advancing it one tooth?
Steve

Supposedly 6k. No I was running out of time so buttoned it up to keep dirt out. When you say advance it a tooth... You mean advance the exhaust so there is 1 more pin between the marks?

Looks like the exhaust mark would be spot on without the gasket. Try that, then count back pins.
Steve

I think I follow you... So keep the same amount of pins between the marks, just advance them both a pin...but the chain should be uniform throughout...

Would being off a hair cause a 20 psi drop like I'm seeing?

Just thought of something...but maybe it doesn't matter. But once the cams are out tdc for 1 is the same for compression or exhaust, right? There's only 1 mark in the crank, not 2 180 deg apart... So it's not like I timed the cams on the exhaust stroke...

PM'd you. That is off by at least one tooth.
Even with a stretched chain it won't be that far off.
With a stretched chain the line might be 1mm above the deck.

There should be no gasket when checking, or at least pretend there is no gasket.

home.comcast.net/~loudgpz/GPZweb/CamsKZZ...Z500550camTiming.gif

The camshaft position is what determines what stroke the crank is on. As long as your cranks is on the TDC "T"mark, and you line up the sprockets correctly and count chain pins as shown, you can't be off. The sprockets only go onto the cams in one possible way.

The drawing shows the chain plates, but ignore the actual plates. Only worry about the pins.

OK, good. makes me feel a little bit better. I did look at your site, after I came in from the garage. It really does not matter if the ex mark points between 2 links vs pointing between 2 pins, right? (the pic shows ex pointing between links and the z/5 pointing between pins 43/44 on one link - but what matters is the number of pins between the marks, yes?

I wasn't really looking at the gasket, I was trying to eyeball it with the head. Another problem I have is the darn 1/4 marks are corroded and hard to see. SO... a 20 psi drop is to be expected then. whew. thank goodness.

Yes, i edited my post. only worry about pins.

Can do. If I moved both cams forward a tooth I bet they'd look good. I was trying like heck to get the marks exactly like the pic. If I could somehow move the chain one tooth forward on the crank I bet it'd be spot on.

Dumb question. Its always bugged me when ppl say the T mark. You mean the line next to the T mark. The F mark also has a line thats used for timing w/ a timing light, yes? So, to clarify you don't line it up with the actual T. (the oem manual shows the line, not the T, but I'm just making sure)

Yes, the "T mark" is the line next to the "T". We don't say line up the "T" because then people might line up the actual "T", hence "T mark".

I guess "T line" would be better nomenclature.

I can hear someone at work say "damn engineers. you knew what I meant"

If it was retarded by one pin, that could explain the lower compression.
Steve