KZ 750 H3 - Valves and Compression

WBPDX wrote:

So I've decided that if I am going to do this, I need to order my parts TONIGHT to have a chance of finishing it by the time I need the garage cleared out.

Right now my shopping list is:

-Manual
-Shims
-Carb boots (maybe)
-Advancer (eBay)
-Complete gasket set (Or just headgasket and valve cover)

Make sure you get the valve seals.

WBPDX wrote:

How intelligent would it be to buy a used head for shim-swapping, and in case I have a REAL valve problem?

I kind of doubt you need a new head at this point.

WBPDX wrote:

For the cost of 8 shims, I can probably buy a used head...

I thought the smaller shims for the four cylinder bikes were cheap and plentiful, I could be wrong.

WBPDX wrote:

What are the odds that my rings are worn, and is there a source for reasonably priced standard size rings?

The chance they are worn is pretty low, the worst case scenario is that they rusted to the walls and now the cylinder walls are pitted there.

New rings and pistons for the four cylinder Kawis are not cheap, I see them on fleabay sometimes.

Patton wrote:

Imo, chances are reasonably good that setting valve clearances to specs may resolve the compression problem, and without any need to remove the head.

I would certainly try that first.

to save some time, you might try the fill the cly with air trick,,, pull the schrader valve out of the compression tester and hook a compressor to it, rotate the engine until both valves are closed and lock it down so it will not rotate, will the cyl with air and listen to see where it comes out, carbs,, intake valves,, exhaust,, ex valves,, inside the engine, rings and or gaskets, may save you some time

WBPDX wrote:

... when I took off the points cover, there was a busted up spring, and what looked like part of the advancer assembly sitting loose, wedged in the cover! The messed up thing is, I can't find ANY of these parts in the fiches. Whats going on here?

Would keep advancer on the shopping list.

Thinking the advancer is a preassembled part, and that the individual components aren't listed separately.

The FSM refers to cleaning and lubing the advancer so it will operate smoothly, and says to replace it in event of any damage to springs, weights, etc.

Good Luck!

Yeah, definitely ordering an advancer...

So there is SOMETHING to be said for water torture and Sea Foam...

A round of sea foam into each didn't seem to change the numbers much; they all gained 5 PSI.

Water tortue brought me to:
130 - 80 - 50 - 115

I did one more round of water tortue and sea foam; just a small amount of water, and a small amount of SeaFoam (it did make a LOT more smoke\steam on the last try though.) And the numbers remain unchanged.

So now it is time for a leak down test I guess.

I didn't do a leakdown because I realised I'd need an compressor or air tank, and I don't have either.

But what I did do is block off the vac ports on the carb, and the petcock (making pri the only ON) - I discovered a few issues with the carb boots while doing this, and now the bike runs surprisingly smooth, and 75% of the time will idle and rev up and down like it should. The other 25% of the time it is having trouble idling, and will occasionally not rev-down.

For right now my plan is to tear into the carbs once more when I get my replacement jet (which alone could be the issue) and replace the valve cover gasket, and check valve clearances at that time (Now that the compression is up.) Then decide what's next.

WBPDX wrote:

now the bike runs surprisingly smooth, and 75% of the time will idle and rev up and down like it should. The other 25% of the time it is having trouble idling, and will occasionally not rev-down.

If you run an engine with too little or no valve clearance, you can burn the valves and the valve seats and destroy the head. You really need to get the valve clearance set right.

I realise I could damage the valves, but honestly, they've been damaged already if they are going to be damaged.

I've managed to loose cylinder #4, as far as running. Previously #3 had died, but I got it back after additional carb cleaning. I have spark on #4, but the carb on #4 is giving me some minor troubles, but nothing that would indicate I should loose it. I guess I will worry about the valves first, and come back to it. I still have lots of compression on #4.

My manual was supposed to be delivered today but they didn't leave it, left a redeliver tag.

Is there ANYONE that can post a summary of the cam removal at least? I just want to know how to position the crank\cams, and if I just slip the chain off the cams, or if there is more to it.

WBPDX wrote:

Is there ANYONE that can post a summary of the cam removal at least? I just want to know how to position the crank\cams, and if I just slip the chain off the cams, or if there is more to it.

If it was a 750 twin, but I never rebuilt a four hole.

I recommed trying this:

if you pop the valve cover off, turn the crank until you align the T (that's the TDC mark) and look at the cam gears. They should have marks to align them to SOMETHING. If there is a numbered position on the cam gear, count the number of cam chain links across between the marks.

Write it all down and you should be able to put it back together.

Got the cams out, was able to read the shims! Looks like I need 7 shims. I quickly tested my two very tight intake valves with the smallest shim I had (on the two cylinders with low compression) and it looks like I need to go down 4 sizes from what was in there!

I consider this a good sign - Proof that valve clearances are probably the main reason for the low compression.

cool !