entropy
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posted July 22, 2002 03:07 AM
paging Y2KZX12R or other expert: question
As you might remember, I'm having Lee's cams put into my 1375 this month. The builder has a ton of experience but the only built 12 he has worked on is mine, so its a "learn as you go" situation.
Q: what valve clearance do you suggest? The cams are being set up at 106/108. Its happening today (finally) 
thanks a million.
BTW could I call you if runs into problems??? If so, pls send me yr ph # to guntekd@texaco.com
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ra12r
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posted July 22, 2002 06:00 AM
Entropy, Lee has built other zx12's so I am confused about this being the first one?!?!?!? He did several 1270's early after the kit was available in 2000.....
He is a busa man mainly, however his engines are not the faster busa's in the circles that I travel.....We race his engines to WIN money cause the owners ALWAYS THINK they have more hp than they really do......might be a "happy dyno" issue?!
See if he will give you a comparative dyno guarentee say give or take 5hp?!??!
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Y2KZX12R
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posted July 22, 2002 07:28 AM
 Edited By: Y2KZX12R on 22 Jul 2002 08:29
I'm not a "bike motor" expert. But...
Well with stock pistons it gets ugly real quick. With stock pistons and my factory installed cam timing of 102.5 I had less than .025" piston to intake valve clearance. The clearance changes about .0045" per degree in the zx12r engine with stock cams.
As far as your cams(ramps) I dont know how agressive they are. If they grind the opeinig ramp speed high it becomes more of an issue. If he is using a valve spring with more than 10% more seat pressure then he must feal the ramps are agressive.
Lucky for you, you have JE pistons with generous valve reliefs so clearance shouldnt be an issue.
The more you advance the intake cam the closer the valve gets to the piston. Basically the valve is opening towards the piston that is going up the bore still. The closest point is when the crank pin is about 8 degrees ATDC.
Sence you are retarding the cam and have generous valve reliefs you are sitting well.
I dont know the lift of the cams you are using but with all the above in consideration I wouldnt think you would need to get closer than .050"
The factory setup with the intake cam at 104 yields about .035"
That is concidered by many to be the minimum on larger valve automotive applications
I'd like to see what Doug Meyer recomends for the zx12r engine.
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entropy
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posted July 22, 2002 07:34 AM
Jim,
LEE is not building my motor. A local guy is doing it with lee's cams on top of my muzzy 1375 (was a 1361).Thx for the info, I am late for a meeting will get back to you with more
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ZRXDean
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posted July 22, 2002 08:02 AM
I've been advised .045 intake/.065 exhaust as numbers to shoot for.
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entropy
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posted July 22, 2002 08:51 AM
Thx for the numbers!
I have now been told that folk within Muzzy have said that min .040 deck clearance is what to shoot for.
A VERY stupid question:
the clearance between the radius on the cam and the bucket on top of the valve???? Lee's cams are about .010 less radious than stock. I am assuming that the builder will use different valve shims to achieve the correct clearance???? Sorry to be so ignorant. 
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entropy
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posted July 22, 2002 09:03 AM
OK, I got in touch with the builder, he said that it had about .070", and that Lee said to use the stock spec for the gap between the cam radius and the bucket.
I am as nervous as a new bride about this motor. 
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krexken
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posted July 22, 2002 09:39 AM
Edited By: krexken on 22 Jul 2002 10:41
I wound up using mostly 75s, 80s,85s and even a 90 to get the clearance back to stock. Naturally my dealer didn't have these sizes in stock so he had to order them. I think that's just the way it is with weld up cams. They have to skim just a tad off the base when regrinding. You could always spring for some oversized valves and have the grinder set them back up to stock specs. Maybe next time, eh? With the extra stroke of your new crank I'd be curious as to what your deck height was. Mine was right at .040 with the shim left out.
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entropy
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posted July 22, 2002 10:15 AM
Ken,
how is the "deck Height" measured/???
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krexken
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posted July 22, 2002 11:59 AM
It's the distance from the top of the block(gasket surface) to the top of the piston at TDC. I use a few head bolts with spacers to mash the block to the case. A good straight edge and feeler gauges will work to measure the distance. A depth mic is best.
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entropy
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posted July 22, 2002 04:40 PM
Thx Ken,
too bad its all buttoned up, but maybe he measured it; i'll ask. The motor was going back in the bike today/tomorrow.
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ZRXDean
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posted July 22, 2002 06:33 PM
Congrats entropy, I hope it's a long and happy marriage Looking forward to seeing the graphs.
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krexken
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posted July 22, 2002 09:57 PM
Gonna have er ready for the Shootout this weekend? I'm planning on going.
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entropy
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posted July 23, 2002 12:24 AM
Dean,
long and happy marriages are built on...... Mastercard!
Ken,
I'll be at the Shootout, just a question of which side of the fence. My job is getting unreasonable, and asking that I actually do something productive these days so I don't know if I'll get the 500 mi break-in done in time. See you there.
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entropy
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posted July 23, 2002 12:34 AM
Dean,
long and happy marriages are built on...... Mastercard!
Ken,
I'll be at the Shootout, just a question of which side of the fence. My job is getting unreasonable, and asking that I actually do something productive these days so I don't know if I'll get the 500 mi break-in done in time. See you there.
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