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Thread: Cylinder skim how much ? |
chipmunk
Parking Attendant
Posts: 1
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posted December 10, 2001 10:49 PM
Cylinder skim how much ?
My standard zx12 runs 304km/h in standard trim with a full akrapovic exhaust and no other changes.
Much to my disgust I was beaten by a modified gsxr1000 by 3 bike lenghts at our usual strip.
I want to take the head off to do a clean up job and a light skim to bump up the compression slightly.
Any suggestions on how much to skim without affecting the reliability ?
Also does anyone know what the standard lobe centres are and any suggestions what to run ?
  
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jessz1
Expert Class
Half the wheels, twice the fun
Posts: 373
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posted December 11, 2001 08:13 AM
There is not to much room in there. Watch piston to valve clearance.
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MadMike
Moderator
FEAR THE BLACK FLAG!!!!!!!!
Posts: 6553
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posted December 11, 2001 01:31 PM
Ditto, watch those valves!!!!!!
MM
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krexken
Zone Head
Posts: 718
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posted December 11, 2001 08:29 PM
The only way to see how much clearance you have is to check it yourself. If you're gonna have the head off anyway, it would be the perfect time to do it and find out. I wouldn't run any less than .060 piston to valve clearance. Naturally, cam timing can greatly affect your clearance. Muzzy recommends 101/105 but this is a highly subjective subject. Surely the gixxer didn't run more mph than you?
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NINJA12
Needs a job
Posts: 3302
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posted December 14, 2001 10:31 AM
"My standard zx12 runs 304km/h in standard trim with a full akrapovic exhaust and no other changes.
Much to my disgust I was beaten by a modified gsxr1000 by 3 bike lenghts at our usual strip. "
You may want to try to get your bike mapped/ or advance the timing before you take the motor apart.
If you take it apart I think 1270 is the answer.
Guy with pc3 maps and dyno run , how much did you pickup with a pc3/pcr3 ?
Help thhis man!!!!!!!!
3 bikes, who left first, shifts better, weighs less.
3 bikes is less than a 1/10 . Most of us vary more that that from 1 pass to the next.
Don't tell anyone but those baby busa's are fast.
The big ones are slow. 
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zx12mark
Pro
Posts: 1278
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posted December 14, 2001 10:01 PM
i guess you know now you don't know how to race.tell him to bring that little toy to st.louis and i'll put him down for you....killer
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Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3744
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posted December 19, 2001 05:47 AM
chipmunk, I wouldnt mill the head instead remove the shim under the block if you want more compression. This will raise the static compression from 12.2 to almost 12.8
Like the others said piston to intake valve clearance must be checked. The intake cam will hit the piston when the centerline is about 103 or so. CHECK IT
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Y2KZX12R
CompetitionCNC.com
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