Midrange ping. Considering quench/squish

So, another good season with the 1075...with one minor problem to solve.

Engine is running great with 60+lbft of torque from 3000-8500rpm - runs like a bat out of hell. But when the engine comes up to full operating temperature there's pinging between 3000-4000rpm. A good hard run for 15 minutes on the highway will do it. I've tried the following:

400 CFM fan pointed directly at cylinders 2 and 3. The fan used to be controlled by an oil temp sensor. Now it's connected directly to the ignition - constantly on. It DEFINITELY helps in city traffic but won't eliminate the pinging.

Large oil cooler. Helps keep oil temp at or below 200 degrees at all times but still pinging.

Retarded ignition timing. Helps but definitely reduces power. No good.

Enrichend needle position. Helps but uses more fuel, darkens plugs and dosen't completely solve the problem.

I also spread my cam lobe centers to 112 deg which helped broaden torque in the upper and lower revs but still pinging.

I only have about 5000 miles on the 1075. Engine burns NO oil and the plugs are spotless so I don't think it's carbon buildup. I'm about to pull the head and start investigating quench/squish.

Am I missing something? If not, anyone out there have first hand experience with this on a KZ?

Thanks, Dave

1075 w/10.25:1CR
0.365 lift cams
RS34 carbs
4-1 w/comp baffle
At sea level and always run 93 octane

davel wrote:

Am I missing something?

octane booster

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

At sea level and always run 93 octane

It sounds like 93 isn't quite enough.

EDIT TO ADD:

Check the timing advancer to make sure it is tracking the proper advance curve (see FSM for the curve). That can cause problems like this. The springs may be weakened.

I'm about to pull the head and start investigating quench/squish.

:woohoo: I would try turning a few more knobs first.....

Took the words right out of my mouth :laugh:

A great octane booster is toluene!
Some info:
Toulene
R+M/2...114
Cost...$2.50/gal
Mixtures with 92 Octane Premium
10%...94.2 Octane
20%...96.4 Octane
30%...98.6 Octane
Notes: Common ingredient in Octane Boosters in a can. 12-16 ounces will only raise octane 2-3 *points*, I.e. from 92 to 92.3. Often costs $3-5 for 12-16 ounces, when it can be purchased for less than $3/gal at chemical supply houses or paint stores.

Works fantastic

What ignition setup do you have right now? As bountyhunter said, perhaps the advance curve is sloppy...

Good luck!

Thanks guys. regading ignition:

I'm running the stock electronic ignition but have slotted the advancer plate, lightened the weights and am using stronger springs. So advance starts at about 2200 with full advance at 3500rpm. Stock weights and springs will bring full advance at about 2500. Total advance is less than stock at around 35 degrees (stock is 40). More than this dosen't increase power. Just more knocking. Less advance reduces power. Verified on the dyno.

(top weight is lightened bottom is stock)

Octane booster is one sure solution. Just don't want to have to think about it if possible. This is my daily driver 9 months out of the year. She's got to be low maintenace...

I had te same problem ,I went with a Dyna 2000 kit from Z1E.Took care of everything.What kind of carbs are you using? Product Overview
The Dyna 2000 for four cylinder engines represents a breakthrough in motorcycle ignition flexibility. The Dyna 2000 system consists of a state-of-the-art microprocessor controlled ignition module along with an adjustable Dyna dual sensor crank trigger. For the first time you can actually set the ignition timing to what you want to maximize engine performance. A number of different advance curve modes and a broad range rev limiter let you tailor the ignition to your needs. Dynatek has added the ability to custom program the Dyna 2000 Sportbike ignition via a personal computer. Like our programmable Harley-Davidson and Dyna FS ignitions the Dyna 2000 can be programmed with a custom advance curve, retard mode curve and RPM limit using the optional accessory curve maker kit. There are also 2 user programmable RPM outputs that can be used to activate a shift lightor other RPM activated device.

kaw-62046 wrote:

Dyna 2000 kit from Z1E.Took care of everything.What kind of carbs are you using?

RS34 carbs.

I've thought about the Dyna2000 before. Seems like a really flexible system. Maybe a good solution.

I didn't know that the Kawa's were quench engines, but if the quench is correct, somewhere between .030" and .045" (below .030" and you run the risk of contact-above about .045" and you loose the benefit of quench), it should actually help defeat detonation, assuming you are running the right octane. Quench effect is not usually rpm sensitive. I ran quench in a lot of Mopar engines and the above was a sort of unwritten rule. True, motorcycle engines are different, but not that much.

I am running a 1200cc engine, I also had a set of rs34fs sold them going with a set of rs36fs.Also what kind of clamps are you using at the carbs to intakes? I found if you use the thin clamps that come with K&N air filter pods you will have to cut them down you will get a better seal.The big hose clamps will pull the carbs away from the intakes and cause a vacuum leak.

davel wrote:

So, another good season with the 1075...with one minor problem to solve.

Engine is running great with 60+lbft of torque from 3000-8500rpm - runs like a bat out of hell. But when the engine comes up to full operating temperature there's pinging between 3000-4000rpm. A good hard run for 15 minutes on the highway will do it. I've tried the following:

400 CFM fan pointed directly at cylinders 2 and 3. The fan used to be controlled by an oil temp sensor. Now it's connected directly to the ignition - constantly on. It DEFINITELY helps in city traffic but won't eliminate the pinging.

Large oil cooler. Helps keep oil temp at or below 200 degrees at all times but still pinging.

Retarded ignition timing. Helps but definitely reduces power. No good.

Enrichend needle position. Helps but uses more fuel, darkens plugs and dosen't completely solve the problem.

I also spread my cam lobe centers to 112 deg which helped broaden torque in the upper and lower revs but still pinging.

I only have about 5000 miles on the 1075. Engine burns NO oil and the plugs are spotless so I don't think it's carbon buildup. I'm about to pull the head and start investigating quench/squish.

Am I missing something? If not, anyone out there have first hand experience with this on a KZ?

Thanks, Dave

1075 w/10.25:1CR
0.365 lift cams
RS34 carbs
4-1 w/comp baffle
At sea level and always run 93 octane

i still had a bit of ping at 5-6k even with timing slightly retarded.....i put in some torco race fuel concentrate and it seemed to work pretty well....i only have one ride using it and i barely got the bike to 190 degrees, but i didnt hear any pinging.....

I have a 1200 and rs34's see my sig below.
I have no ping. I run premium at any pump, wich can be 91 to 93 octane.
I think it is due to 3 things. I run a Dyna2000 (with 2.2 ohm coils), and i have reduced the squish clearance. And possible, more cam overlap.
The Dyna has a built in curve for higher compression. This changes the acceleration and duration of the curve.
If u reduce the squish clearance, u will get a better burn.
I would not recommend going less than .040" for a street motor. u can get away with .030" on a strip motor. Remember that your gaskets will compress. .040" should be the final clearance after compression of the gaskets.
also check for any sharp edges on the piston valve relief’s, spark plug holes, valves. sharp edges cause hot sports and pre ignition. i softened all of the sharp edges on my new J&E pistons.
Works for me.

polkat wrote:

I didn't know that the Kawa's were quench engines,

I'm not sure either but it seems like they're not due to the domed piston and hemi combustion chamber. Seems like the combustion chamber would look like a thin dome shaped sliver. I'm thinking about taking a cast of the CC with the piston at TDC then slicing the cast in half and measuing the thickness at different areas. If I do this, I'll post the results.

mark1122 wrote:

i have reduced the squish clearance

Mark, How did you accomplish this?

thnx

Put 2 pieces of solder into the plug hole. direct 1 to each side of the piston, above the wrist pin. While holding them in place, turn over the motor by hand. now measure how much the solder squished down to. I’m not sure what the stock clearance is? .80” to .100”? when u do this after a clearance reduction, u will need thinner solder.(about .060”)
After u take the motor apart, measure the head, and base gasket thickness. U can compare this thickness to a new gasket, to get an idea of the how much they will change. The base gasket compresses more with bigger bores.

Now u can have the cyl milled to achieve your desired clearance.
If u decide to do this, I would take the top case in with u. have them checked it for true. u may find, like I did, that they are not. Also verify that the distance from the crank bearing surface to the case surface is the same on #1, and #4. Mine were not. T
Truing this surface will also, help prevent the dreaded, base gasket leaks as well.
If it must be milled, u will deduct the amount removed, from the amount u must take from the cyl.
I would consider .040” clearance as a minimum. Try for .045” to .050”. This will give u leeway if your gasket compresses more than anticipate.
Also , I use Ape cyl studs for more head torque.
My cases, cyl, and head have been milled so much that I now run a .050” aluminum base gasket, to achieve the desired squish clearance for the street. A stock base gasket is .020” thick.
It is too much heat, that causes detonation.
When the spark plug flame starts to travel across the cyl. Hot spots can ignite fuel in another area. When these 2 flames collide ,u get a knock.
The tighter squish clearance helps to keep the fuel mix from stagnating at the edge of the cyl, just waiting for a hot spot to ignite it.


I would not consider this as a must for a street motor. A lot of guys run 10.25:1 pistons without ping issues.
I just feel that when I have a motor down , I may as well put everything in my favor.
I like to pay attention to all the minor details. It will cost a little more , but I find it satisfying.
1 other minor detail. If u bast the motor and paint it with a thin coat of black paint, it will increase the cooling potential by 15%. I also drilled holes in the cyl cooling fins. Heat is your enemy.
I hope this is of some help.
Mark.