entropy
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posted May 02, 2004 03:55 AM
 Edited By: entropy on 2 May 2004 05:03
valve spring pressure: measured
"japped up" rig, but it seemed to work. Valves are installed but with head on bench.
drill press, dial indicator, digital bathroom scale
Muzzy valve spring kit (zx12), has .401 int cam lift, .390? exh
measured:
max distance to coil bind = .600"+/-
seat pressure = 60# (+/- 2#) I took measurement when spring just started to compress
spring pressure @ .400" = 130#
spring pressure close to coil bound = 180-190#
Do these numbers look reasonable????
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krexken
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posted May 02, 2004 04:22 PM
60lbs is almost exactly what I got with my new HD zx11 springs for a zx11. I don't recall what it was off the seat. I'd say your scales are pretty close. Any good hp engine builder should have a good set of scales though. My next door neighbor just happens to be one.
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VincentHill
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posted May 02, 2004 04:44 PM
What were your "Stock" Springs seat pressure at install Height?
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Ra12r
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posted May 02, 2004 05:09 PM
The million dollar question is how much spring pressure is needed to follow the cam profile at .358 or .405 lift. I had also found that approximate reading about spring coil binding.
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entropy
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posted May 02, 2004 10:59 PM
i have no idea what the stock springs' seat pressure is, i was hoping someone could tell me. 
It's good to know that the the 60# and coil bind length are reasonable (thx Krexx & ra).
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VincentHill
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posted May 03, 2004 06:42 AM
Ent, the reason we both need the answer to this question is, Using NOS and the Air Shifter you need 30 more pounds of seat pressure to keep from lifting the exhaust valve off of the seat (During the larger explosion when shifting and the NOS & fuel build up). I hope that stock has about 30 to 40 Pounds! Great stuff Ent!
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entropy
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posted May 03, 2004 08:26 AM
VH,
I believe that stock is 30-40# as you say, but I haven't seen any specs. 
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BA
Pro
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posted May 04, 2004 01:50 PM
Hey Entropy, forgive my idiocy here, but are these measurements on stock springs are are you using HD Busa springs or what?
Thanks man!
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krexken
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posted May 05, 2004 02:24 PM
I used a .400 lift intake cam with Lee's springs(whoevers) at 60lbs of seat pressure. Bike had nitrous and saw the llimiter several times with nitrous on, no probs. My bike never popped when shifting with my kill box. I had over .060 piston to valve clearance also. More is better.
He's using Muzzy's springs for their cams.
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entropy
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posted May 06, 2004 02:36 PM
BA,
Yep, like ken says, "muzzy" springs. They might have been sourced from Kibblewhite by muzzy, not sure.
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entropy
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posted May 06, 2004 02:42 PM
Edited By: entropy on 6 May 2004 15:43
.
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Ra12r
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posted May 16, 2004 05:29 AM
If the springs bind at .600 lift, then the spring pressure at .358 lift must be around 100lbs if the seat pressure is 30-40lbs. With a .400 lift then those same springs would have even higher pressure at max lift. Question, why is stock springs NOT strong enough to follow the aftermarket profile??
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