IslandRider
Parking Attendant
Posts: 15
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posted December 23, 2002 06:43 PM
Head to pistion clearance??
Anyone know what the piston to head clearance should be on a 1361 to obtain the advertised 13:1 ratio? Also, what kind of cylinder pressures should I expect on a fresh motor?
  
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krexken
Zone Head
Posts: 732
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posted December 23, 2002 10:33 PM
Not sure about either but I wouldn't go closer than .035 on piston to head clearance. I left out the .010 base shim to get .040 clearance. Cyclinder pressure can vary a lot with different cam timing numbers.
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fastestr1
Expert Class
Posts: 300
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posted December 24, 2002 06:23 PM
 Edited By: fastestr1 on 25 Dec 2002 12:20
Why would the value cleance be an issue if it is set to stock and since it has value reliefs in the pistons, unless you milled the head.
Krexken what is the stock clearance, .050?
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Black 02, 8.99 @ 161.95 motor on NOS
Put one knee down for the curves and both knees down for GOD
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krexken
Zone Head
Posts: 732
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posted December 25, 2002 08:29 AM
Don't know the stock clearance either. Piston to valve clearance is a very big issue, on almost any bike when the cams are being set. Every piston has valve notches but the cam timing needs to be within a certain range to get proper clearance. Cam timing will radically affect this clearance. I'd never assemble a hot rodded motor without carefully checking theses clearances. One simple mistake can ruin an engine quickly.
K Cadby or Y2KZX12R could probably enlighten you on the stock piston to head clearance.
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VincentHill
Needs a life
Posts: 6520
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posted December 25, 2002 07:25 PM
I always used a piece of rosin core Solder through the Spark plug hole to measure. I have "NEVER" run under 1 MM. Increasing the timing of the exhaust Valve can really get you too close!! Be careful.
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Made History @ Daytona and still one fast old man!!
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kcadby
Pro
Posts: 1733
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posted December 26, 2002 11:30 AM
If you remove the base gask...it WILL retard both cams a bit...so you NEED to check valve to piston clearances and use adjustable sprokets to get safe clearances...
One STOCK MOTOR that I took apart...had LESS THAN .040 valve to piston clearance...SHOWROOM STOCK!!!
I'm REAL stoo-ped when it comes to remembering all the #s and the piston to head clearance on stock pistons is one I don't recall at the moment...
Another interesting fact though...when I CC-ed the head on one ZX12...from one end to the other...each chamber had EXACTLY .2CCs less than the one next to it...
Another words...the chamber on one end of the head had .6CCs less than the chamber on the Other end of the head 
Just thought I'd throw that in...to mess with you guys...
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MadMike
Moderator
FEAR THE BLACK FLAG!!!!!!!!
Posts: 6579
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posted December 26, 2002 01:20 PM
Kevin, how exactly do you CC those? I know that sounds like a dumb question but before I put the 1361 back together I want to do this also?
thanks
MM
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VincentHill
Needs a life
Posts: 6520
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posted December 26, 2002 03:01 PM
I would like to know also because I am sure that my "Old" Way is out or step. I took a Glass plate and shot a BB Through it for a Hole and put a little grease around the combustion Chamber to seal it. Then Using a Burette, added fluid until I had the fluid was convex out of the hole.
Way too hard to seal the Piston and torque everything and have the piston at TDC and use the spark Plug Hole. one of the things I found that changed the CC was the Valve Job. just sinking the valves a few thousand, really throws things off.
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Made History @ Daytona and still one fast old man!!
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kcadby
Pro
Posts: 1733
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posted December 26, 2002 03:16 PM
Same way as Vincent accept...make your plate out of Plexiglas...
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VincentHill
Needs a life
Posts: 6520
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posted December 26, 2002 09:10 PM
I made my plate "Before" Plexiglas was invented!
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Made History @ Daytona and still one fast old man!!
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ZHooligan
Moderator
Post Whore Extraordinaire!
Posts: 3829
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posted December 26, 2002 09:20 PM
I was going to make a smart ass remark but I forgot what it was we were talking about!
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