Piston to head clearance

Like I posted before Mark.It will make a differnce between a engine that will run or one that will kick some ass!! set yours up at .040 and fell the POWER .

kzz1p wrote:

Hello Everyone!
This is my 1st. post on this site.

I was told a number of years ago by a man, let's call him B.H. He told me that when you run zero deck height (pistons flush with the top of the cylinder)It increases bottom end and mid range. Your top end MPH will be hurt greatly. He said these bikes had good torque from the factory but fell short in the MPH area. He told me the answer was to have a .035" deck height to increase my MPH. I tried it, and it made the differance between night & day. On all of my bikes I shim or mill the cylinder until I reach my .035" deck height. Chevy's seem to like zero deck height but not Kawasaki's. Maybe next time you build an engine you might just give it a try!

are u saying .035" below the deck?? That would be worse than stock wouldnt it? what is the stock height?

kaw-62046 wrote:

Like I posted before Mark.It will make a differnce between a engine that will run or one that will kick some ass!! set yours up at .040 and fell the POWER .

Please excuse my poor memory. I cant recall wich post that was? Anyways please remind me.
Have you run .040" succsesfully on the street? how many cc's what cams? Was this kz? This is the data i need. i want to run it close but i am not willing to ruin my motor tring to find out the min.
.043" is for a copper head gasket and a cometic is more like .047" i will have to measure mine. Pm me if you whant the #.

#251347
kaw-62046 (User)

Posts: 49



Re:Degree Wheel Setup & CAM Tutorial? 1 Month, 1 Week ago
Here are the spec's that my engine builder give to me for future referanes.On a spreed sheet on C-D
Bore- 2.992"

Stroke- 2.596"

Head Gasket Thickness .043"

Head Gasket Diameter 3.012"

Piston Height .003" above Deck

Combustion Chamber 36cc

Dome Volume 10cc

Compression Ratio 10.75/1

Displacement 1200cc



Valve Spring Information for Web Cams Springs VS-K10 Intake Exhaust
Installed Height 1.320"- 1.340" 1.320"- 1.340"
Seat Pressure 90psi 90psi
Open Pressure 240lbs@.425" lift 240lbs@.425" lift
Max. Valve Lift .425" .425"
Coil Bind .575" lift .575" lift



Camshaft Specifications for Web Cams Grind #110 Intake Exhaust
Valve Lash .006" .006"
Valve Lift .395" .395"
Duration 284* 284*
Duration @ .050" 256* 256*
Lobe Center 106* 108*
Lobe Seperation Angle 107*
Valve Opens 22* Before TDC 56* Before BDC
Valve Closes 54* After BDC 20* After TDC
Cams Installed @ 106* 108*



Valve Information Intake Exhaust
Head Diameter 37.5mm 31mm
Installed Height #1 - #4 1.486" 1.485"
Valve-Valve Clearance @ Seat .180"
Valve-Valve Clearance @ Overlap .059"
Valve to Piston Clearance >.130" >.130"
Cylinder Head Information Intake Exhaust
Valves 37.5mm SS "J" Model 31mm SS KZ 1000
Retainers Stock Steel Stock Steel
Keepers Radius Groove Radius Groove
Springs WC VS-K10 WC VS-K10
Spring Shims
Cylinder 1 0 .015"
Cylinder 2 0 .015"
Cylinder 3 0 .015"
Cylinder 4 0 .015"
Shim Bucket Type SOT SOT
Valve Shims
Cylinder 1 2.6mm 2.5mm
Cylinder 2 2.6mm 2.5mm
Cylinder 3 2.55mm 2.5mm
Cylinder 4 2.65mm 2.5mm
Valve Angle Cut 2 2
Seat Angle Cut 3 3
Cylinder Head Type KZ 1000


Piston Information on JE #132493
Rod Length 5.3905"
Dome Height .190"
Compression Distance .979"
Valve Pocket Depth Intake .140" from Deck
Valve Pocket Depth Exhaust .080" from Deck
Top Groove .040"
Second Groove .0485"
Oil Groove .111"
Pin Diameter .669" = 17mm
Pin Length 2.253"
Pin Retainer JE .050" Wire Lock
Target Piston Weight 226g
Piston to Cylinder Clearance .0025"



Crank Shaft Information
End Clearance- Out of Cases .014"
Connecting rod Side Clearance
Journal 1 .016"
Journal 2 .015"
Journal 3 .015"
Journal 4 .016"
Crankshaft type Mark II - Welded
Rod Wrist Pin Diameter 17mm



Cylinder Information
Sleeve Type Weisco 1200cc- New
Ring End Gap Top Second
Cylinder 1 .014" .020"
Cylinder 2 .014" .020"
Cylinder 3 .014" .020"
Cylinder 4 .014" .020"


Carbuerator information
Carbuerator Type 34mm Mikuni Flat slide
Main Jet 140
Pilot Jet 20
Accelerator Pump Yes
Needle Location Center
Needle Length
Please note, although no boardcode and smiley buttons are shown, they are still useable

Yes Mark, I am saying below the top of the cylinder(negative deck height) I don't know what the stock deck height is. Everyone has their own ideas, I humbled myself and turned to someone that knows a lot more then I, will ever know. I did what he told me to do, the minute I got home.It took me two base gaskets to get my .035" and it worked very well for me. This slight loss of compression can sometimes made up by surfacing the head. Myself, I make up the differance through cam timing to increase by cranking compression. Yes this does go against most common thinking. Maybe thats why I kept it to myself for 20 years. It has made a big differance in MPH for me.I will be doing the same thing on the project I am working on now & the two that fallow it. Please take it for what it's worth.

OOOOHH YEA ! That post!
OK. So how do we know this is a safe #? Does your builder have personal experience with this clearance?
Who is your builder.
Sorry if i sound skeptical ,I just need to know for sure. My builder said .040” too, but Paul Gast tells me to go with .050” to .055”. That is hard to debate.

Your build is almost identical to mine. MK11 welded crank, same pistons. I’m using the old RC400 cams witch are almost the same grind as yours. .425” lift, 260* duration. Same intakes, I have stock exhaust valves. Larry Cavanaugh ported my head.
Back cut trany , billet 2nd.

Be sure to check your valve to valve clearance after degreeing the cams. You should be ok with the .180” seat spacing but u should check everything to be sure. Even check the piston to deck height on booth #s 1 & 4 .This will asure that all deck surfaces below ,are true to the crank. I had to have my cases corrected for this.
Oh , 1 more thing, do NOT use APE clutch plates. They are thinner and will ware the basket unevenly and cause clutch grab. Been there.
I'm allways open to advice, if u want to throw some my way.

Please help me understand. You have a 1200cc motor with 10.75:1 compression. Aren't the web 110's drop-in cams? or very close to it? You have the deck height at +.003". Is that the dome? Or the outside edge of the piston?
It sounds like a very good torque motor.

kzz1p wrote:

Please help me understand. You have a 1200cc motor with 10.75:1 compression. Aren't the web 110's drop-in cams? or very close to it? You have the deck height at +.003". Is that the dome? Or the outside edge of the piston?
It sounds like a very good torque motor.

The .003" is measured at the edge of the piston above the pin boss.
Web110's may be drop in not 100% sure.
The reason u want a tight sqish clearance is to improve the fuels burn . This will help prevent detonation,thus, make it easier to run pump gas.A by product of tighter squish is higher compression. this will give u more torque.If u dont want more low end torque, u can retard your intake cam timing for more top end or change the cams out for a set with more duration.

Snakebyte wrote:

I've been away for a while and I am catching up on the threads.
Does any one know the compressed thickness of the head gasket, for graphite and shim. As this will play a role in quench area?

i use a cometec head gasket. I dont think anyone else makes a fiber gasket for the KZ's? They have a gasket material (paper?)on the outsides and metal inside.
I measure the 2 that came out of my 2 motors and got .038" on my 1327cc and .042" on my 1135cc motor.

kzz1p wrote:

Please help me understand. You have a 1200cc motor with 10.75:1 compression. Aren't the web 110's drop-in cams? or very close to it? You have the deck height at +.003". Is that the dome? Or the outside edge of the piston?
It sounds like a very good torque motor.

alomost drop in. I had to grind to lobes to make them 1mm smaller otherwise they did hit the head.
Much torque when intakelobe at 104,5 degrees.

Retarding the intake cam reduces the overlap, moving the RPM range down on the scale. It closes the intake valve later. The later closing of the intake timing event reduces the cranking compression therefore cutting the risk of detonation.The squish clearance is important on hard core race engines. If it's a street bike, why turn it into an engineering project? If you have built many engines you may want to push your own limits and skills. If you are a 1st. time builder keep it simple and have fun.Torque is good for smoke shows, quickness & moving heavy bikes.Torque can sometimes be harder to hook up. Torque will get you there quicker,Horsepower will get you there faster.Myself I like cams with streetable lift and duration. I mainly look at the overlap. I see for example: cams with (.410" lift/300*duration)most companies have them. The differance is the overlap in most cases.Where do you want the Power? Small overlap= torque, big overlap=HP.
Everyone does it different! Whats the old saying "There are more then one way to skin a cat"

Just to add a note- The exhaust valve is open when the piston is moving upward,therefore if you loose control of the exhaust valve or miss a shift. You have a greater chance of the valve hitting the piston.