I am not retarded. Should I be?

So Patton, would you recommend against a timing change?

I recommend you "not" use two base gaskets, aside from the likelihood of oil leaks, it's also likely to make the pinging worse.

With those kind of static compression numbers, I don't see compression causing your problem. B9's might help.

Is the bike using any oil? Is the bike running a little lean in the midrange? at what rpm does the pinging occur?

steell wrote:

I recommend you "not" use two base gaskets, aside from the likelihood of oil leaks, it's also likely to make the pinging worse.

With those kind of static compression numbers, I don't see compression causing your problem. B9's might help.

Is the bike using any oil? Is the bike running a little lean in the midrange? at what rpm does the pinging occur?

Steell, no--not using oil. I don't think I am lean in midrange. The reason I say that is that recently, I was struggling with a low range stumble when I just come on the throttle. Someone suggested I raising my needles to make it richer. My needles only have one clip position, so I shim'd them. It ran terrible with the shims, so I took the shims back out. So I don't think I'm too lean in the middle. My wife would agree with that.

As for using B9s, is there any downside to that?

FWIW, the FSMs show "standard compression" of 145 psi for Z1-KZ900 and 128-156 psi for 1977-79 KZ1000. Sorry I don't have the FSM's 1982 figures for the large fours. But 165 seems plenty tight.

Perhaps the head was trued (shaved) enough to bump compression psi.

What head gasket is fitted, and is a thicker version available that would withstand these compression figures?

Tan color plugs would indicate correct fuel mixture and heat range, and thereby seem to mitigate against "overheating" as the cause for pinging under load. But won't hurt to give B9's a try.

While test running with the shimmed (raised) jet needles -- which proved too rich -- was it noticed whether the pinging was reduced or eliminated?

Am unaware of the reasons why retarded timing would allow higher top speed or why dual base gaskets would incite more pinging. But agree with the "sigh" when thinking of the pita base gasket r&r, and enhanced leakage propensity with dual gaskets.

Would concur that slightly retarding the ignition timing is likely the most expedient way to eliminate the pinging.

Good Luck!

Patton,

No, the head was not shaved--by me at least. Not sure if the PO did it.

These are non-stock Wiseco 10.25CR pistons, so I would expect the compression to be higher than stock.

Did not notice whether the pinging was still there with shimmed needles. I was paying more attention to carb performance at the time.

Thanks again.

The reason the double base gaskets (or thicker head gasket) may make the problem worse is that you are effectively doing away with the squish band, and this will create a "dead zone" of gas that is likely to cause detonation. It's amazing how far advanced the knowledge of combustion understanding has advanced, look at the 12-13:1 static compression ratios of newer sport bikes, and they run on pump gas.

An excellent article on detonation , the drawing showing a squish band in a combustion chamber illustrates what Kawasaki started doing in 83 with the GPz750 and GPz1100 motors.

You say that the plugs are tan in color, but you don't say if that's at plug chops at various throttle openings. If that's just taking the plugs out after they have been used for awhile in normal riding with a mixture of throttle openings, that only tells you the average mixture, not what's happening at mid range/wot.

You need to do a plug chop while it's actually detonating to see what's happening with the mixture.

The combustion chamber and piston top designs of the KZ's suck when it comes to increasing compression, everything has to be just right to run higher compression in these motors. Even when every thing's right, you still can't open the throttle wide open at high load low rpm conditions without experiencing detonation.

And you still haven't told me at what rpm, throttle position, and load, you are getting detonation

steell wrote:

You need to do a plug chop while it's actually detonating to see what's happening with the mixture.

How quickly does plug color change when combustion conditions change? The pinging I get only happens momentarily when I accelerate hard. I don't know how long I can maintain it in the band where the pinging is occuring to get an accurate plug read. And do I need to do this with fresh plugs? Or when it enters the pinging band, will the plugs change color instantly so that if I cut the engine and pull the plugs, I will get actionable data?

And you still haven't told me at what rpm, throttle position, and load, you are getting detonation

RPMs is not known right now as my GPz Cams have no tach gear. I am working on getting an electronic tach for the bike, but I don't have it yet. However, the pinging occurs as I accelerate from low speed at about 1/2+ throttle. And with a weight of 270lbs, I'd say that the load is always substantial when I'm riding.

Skyman wrote:

I know that some pinging is normal, but how much is too much?

I don't think pinging is normal or good. You might actually benefit from some real octane booster like Octane Supreme 130. It can jack the octane 5 or 6 points easily, the junk they sell at pep Boys can only raise it about a half point or so.

www.batterystuff.com/fuel-treatments/OS6q.html

quader98 wrote:

sorry,not that i do it but why is octain boost not good to use all the time

$$$$$$$ :laugh:

Skyman wrote:

Patton wrote:

Imo, zero pinging is best.
Probably already done or considered,
but besides timing, am thinking:
Running high octane (pump) gas?
Compression psi too high (beyond factory specs)?
Carbon build-up in combustion chamber?
Correct spark plugs and gaps? Plug reading?
Perhaps try one step colder range plug?
Feasibility of using two base gaskets
to slightly lower compression?

Good Luck!

Thanks for all the good suggestions.

FYI, compression is 155-165-155-165.

Plugs are B8ES. All read tan now (I was previously getting soot in #1 only, but fiddling with the carbs, I think I finally got that problem solved). I guess I could try B9s.

Two base gaskets? [sigh] I guess I COULD try that. Just not too excited about tearing down the top end again. Maybe over the winter.

Thanks again.

With the Octane 130 stuff, you only need a couple of ounces per gallon of gas to get about a FIVE POINT octane increase. You might not even need that much jump to stop the pinging. Carry a 14 ounce bottle of it (use an old bottle from fuel injector cleaner) and you will be able to cover three tank ups.

I think I got a case of 12 quarts for about $100 last year. That's cheaper and easier than a whole engine teardown, and you won't have to give away the HP that will go with the lower compression from adding another gasket.

My 1105 motor runs fine on premium fuel at 10.25-1, but then I rode the little short yellow school bus too

Ok, what you have done is make yourself a high rpm sportbike motor, and you can't lug it like you could the stocker.

That's why Kawasaki didn't put the high lift longer duration cams and higher compression pistons from the GPz1100 in the KZ1100 shaft.

Now, you either ride it like a sportbike motor, or it's going to complain.

It's called "Horses for Courses", build the motor to fit your riding style, don't build a race motor for the street (unless you're street racing, then live with the consequences)