entropy
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posted April 12, 2003 06:04 AM
finally got a compression test...
My bike is back running again, with only a few tweaks before I pick it up early next week.
This time I had the builder measure compression psi before bolting the motor fully in.
Consistent 250-255 psi accross all 4 cylinders spinning with battery, all plugs out. This is with billet block, billet crank, Lee's cams, Cometic solid copper head hasket and 2 base gaskets.
Any comments?
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addisonzx12
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posted April 12, 2003 07:23 AM
Going to be a little touchy with pump gas. Especially when hot, probably could use a touch of octane booster.
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posted April 12, 2003 07:27 AM
255????
holy crap.....umm....heh...wow.
I did the first cyl on mine (stock motor though) and it was 155 :/
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zrxdean
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posted April 12, 2003 07:51 AM
That sounds good to me - the ZRX makes 240-250psi and runs fine on 93. Of course every bike is different, yadda yadda. Did Sabin (right?) CC the motor to see exactly where the CR ended up?
Can't wait to hear how your ALPHA ZX12 runs 
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kawachan
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posted April 12, 2003 08:15 AM
WOW!! Hmmmm......8.90's SOON!!
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MadMike
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posted April 12, 2003 08:22 AM
Yea!!! Yea!!!
man go get em!!!!
I cant wait to see you make a pass on that baby!!
Mad Mike
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kcadby
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posted April 12, 2003 10:07 AM
Billet Block?!?!?!
CRAP!!! I was told that the machine shop STILL has the pistons for the one I'm "trying" to build 
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kcadby
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posted April 12, 2003 10:36 AM
OK...I've got my lunch and I feel better now
That sounds good Karl...
Cam timming makes a big diff. in "cranking comp." and...the motor WILL have more compression after it has been run for the first time...rings will seal better 
Sounds like yer gonna have FUN...AGAIN!!!
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RAC4IT
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Bergie
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posted April 12, 2003 11:42 AM
what's good news for one (entropy) is bad news for another (ycis) I suppose
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your car is slow
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posted April 12, 2003 11:51 AM
heh...well...im assuming his billet block setup should be of significantly higher compression than my stocker.
However I was not expecting 100psi difference :/
Time to look at the other 3 today.
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Cmarsh93z
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posted April 12, 2003 01:10 PM
13 to 1 on the billet block if Im not mistaken.. what the comp ratio of the stock motor?
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kcadby
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posted April 12, 2003 03:49 PM
Stock is 12.2 and..."Useable Range" (manual lingo) is 149-228psi
I'd be looking for another guage to compare with the one you used Brian...
My guage shows 225-235 on John's bike...
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your car is slow
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posted April 12, 2003 04:48 PM
I went back and did the tests again 175, 165, 185, 175 reading left to right.
Now Ill do it yet AGAIN since my dumb ass forgot to open the throttle while doing the tests :/
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INTRA
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posted April 12, 2003 04:59 PM
My Blackbird was 130 across,must be the pistons.Carl,get that thing on the dyno.
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ZXALAN
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posted April 12, 2003 05:21 PM
DAYYYUUUMM! You better have a DAMN good battery in that thing Karl and I would keep a battery tender on it all times. That thing is gonna be a HOSS. You taking it to Sabins for a map job or gonna try Cheese out? Gettin that thing on a suzuki dyno should help it out!  you saw what it did for AA's 636, 109hp, bone stock w/Nuetec. 230hp or bust eh Karl?
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ZXALAN
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posted April 12, 2003 05:24 PM
BTW my busa had 175,175,169,175 with yosh cams degreed to 105,107 and 16k miles. KEV, 230psi stock??? Maybe you should check your gauge?? Thats why that fuka runs 9.0s!
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kcadby
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posted April 12, 2003 05:57 PM
I haven't cross checked any other guages...yet...it read 225 on the FIRST 1270 that I ever built ...
I did some combustion chamber work and didn't shave the head to make up for it...yet...
John's were 230-235...I checked both bikes (John's stocker and Eric's 1270) one right after the other so...the numbers on Eric's disapointed me but...I DO know why the 1270 was low-er...
My OLD Snap-on guage might read high...
I AM "AT Sea-Level" here though you know!?!?!?
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your car is slow
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posted April 12, 2003 06:17 PM
those numbers with the motor warm? or cold?
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entropy
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posted April 12, 2003 07:07 PM
The 250-255# were obtained cold, with the motor not yet run since the recent rebuild (rings & bearings). Its such a pain in the ass to get compression on a 12 the builder hooked up the lower motor mounts but not the top so it was leaning fwd enough to get at the plug holes.
The motor is set up the same as I had before which did 222hp SAE on Nutec (229 uncorrected) late last year. The chamber has not been cc'd.
Big hoss battery & custom box (thx Chuck/Lee) is ready, I'll mount it between the swingarms ahead of the tire.
I spent all day in Austin at #1 son's honor society induction but my mind was elsewhere...
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your car is slow
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Fuck Nitrous...Got Boost?
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posted April 12, 2003 07:59 PM
Its gravy to do the test with the jc whitney tester ...although it may not be all that accurate I suppose.
Anywhoo..you get 2' of flexible hose from the gauge that ends in a quick release fitting...then another 10' of hose that you can swap out the plug sized fittings onto....basically just slide the small hose into the hole...twist it tight..then quickconnect it to the main hose.
Can do them all in a matter of minutes from either side with ease.
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kcadby
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posted April 12, 2003 10:09 PM
Always warm when you can Brian but...being consistent is more important than anything...
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ZXALAN
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posted April 12, 2003 11:09 PM
Damn Karl, when that thing is warm its gonna make prolly 10+ more psi, not to mention after the rings seat. Thats gonna be a BAD MUTHA PHUCKA!
Kevin, I was just jackin with ya about your gauge. Those numbers do sound high though, maybe not on the 1270 but the stocker..???
Cheese did a check on a fresh 1397 with megacycles and it was around 195psi I think he said but cam timing you know....... I can't wait to see Karl's monster run. We'll have to put him on an IV and a respirator to keep him stable after the 160mph trap speed.
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entropy
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posted April 13, 2003 03:01 AM
Alan,
hahahahahahaha, a respirator for the big end, eh???
I don't think it should run any stronger than before because its the same set up. All I want is to be able get thru 1st without flipping it over. The longer arm won't arrive for a couple weeks, so maybe I'll do some road work with the street tire for a change. I may take it back to Jim at Sabin to tune the 1000-7000rpm range. He didn't do that last time because I said hi rpm only, but now I'mm thinking more about lo rpm launches and pinning it, especially with the 10" arm (if it ever arrives... )
Yr Grocery-getter will smoke me pretty easy, especially with THE Ethiopian Test Pilot at the controls. It'll be good to see you back at the track.
YCIS,
good tip on the JC Whitney set up. Thx!
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your car is slow
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posted April 13, 2003 09:14 AM
that post should say addition 10"...not 10'
still plenty enough to get into the cyls.
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entropy
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posted April 13, 2003 09:37 AM
I was wondering about the 10'
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