silver01bullit
Expert Class
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Posts: 333
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posted September 02, 2002 06:03 AM
JE high comp. pistons?
I noticed on JE's website that they make a stock bore 13:1 kit. Anyone heard if these will require any machining or if they're simply drop-in and go?
   
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oldkawboy
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posted September 02, 2002 11:13 AM
I don't know about the pistons but if you want to stay stock bore and bump your compression, just remove the base gasket. I did it and according to Y2K Jim, it will raise the 12's compression by about .6 of one point, getting close to your desired 13:1. It's easier and way cheaper than the pistons, $4 for the sealant and it's still "stock".
My gasket/shim measured .010".
Dan
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ZHooligan
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posted September 02, 2002 02:41 PM
A set of JE pistons are pretty spendy and require a fair amount of prep before installing them. I would suspect Weisco has pistons for the 12 as well. The Weisco pistons are significantly cheaper even though Weisco actually owns JE now. The trick of removing the base gasket is a good one.
____________
To those who do not count their life in years, but in how life
has touched them in the past and how much it can hold in the
future; -- Youth is forever.
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Y2KZX12R
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posted September 03, 2002 03:48 AM
Silver, if you remove the block shim, check your intake valve to piston clearance. Try to stay around 105 on the intake cam CL. 104 gets close.
12.2 is stock CR and 12.8 is with shim removed.
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silver01bullit
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posted September 04, 2002 04:45 AM
Thanks guys, I was curious about the removal of the base gasket myself but was unsure about how well it would seal. As for the seal part, are we talking about just some gasket sealant? Also, I'm sure the stock bikes all vary from bike to bike but I was curious what the norm is on the cam timing. I'm not in a position (at the moment) to spend the dough on the cam sprockets and degree wheel etc. Thanks, you guys have helped a lot!
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Y2KZX12R
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posted September 04, 2002 04:48 AM
from the factory my bike was 102.5/101
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ninja12
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posted September 04, 2002 12:45 PM
y2k, did you buy the adjustable sprokets, or use the stock cam sprokets.
If stock were any mods needed. Just to remove the base gasket, no piston upgrade.
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oldkawboy
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posted September 04, 2002 02:49 PM
I used Yamabond but a number of sealers will work. I was concerned about leakage around the cases but Y2K said not to worry...and as always, he was right.
Ninja12,
No other mods are needed, just make sure the surfaces are very clean. I bought adjustable cam sprockets from Muzzy.
Dan
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Y2KZX12R
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posted September 06, 2002 02:10 AM
I have APE gears. If you want to remove the block shim you need to degree the cams. If I had just removed the shim and not degreed the cams when my intake was 102.5 from the factory, then my intake valve would have been about .012"-.015" from the piston. Thats too close. So I moved the intake cam to 105.
I have sence moved it to 102 again but I cut the intake valve reliefs in the pistons .015" deeper.
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ninja12
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posted September 06, 2002 11:02 AM
Any advantage with APE over Muzzy? How about price?
All info appreciated!
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supraman95mb
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posted September 06, 2002 11:11 AM
man this is some good stuff!!! Will this work on a 2002? Is the gasket identical in size?
OldKawboy and Y2K, what hp increase did you see by doing this? (Oldkawboy, Chad, If I get this done and get some cam gears, would you guys be interested in helping me put them on and or understanding what I need to do to be safe!!!!
____________
02 Stroked 12R
95 Supra Single Turbo 750+ hp
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silver01bullit
Expert Class
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Posts: 333
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posted September 06, 2002 02:55 PM
Yeah, I'm certainly interested in doing this but since I wanna do it right I'll invest in the gears and degree wheel as I'm not very interested in cutting valve releifs in my piston tops  .
Y2K,
If I set the intake to 105, this will compensate for any rod stretch at high heat/rpm's?
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Y2KZX12R
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posted September 06, 2002 06:54 PM
 Edited By: Y2KZX12R on 6 Sep 2002 20:06
ninja12, I dont think APE has the best way of indexing the gears to the hub. Muzzy might have a better setup? I havent seen the muzzy gears.
The APE gears are a bit cheeper, but the muzzys might be better. Like I said I havent seen the Muzzy gears.
But Muzzys is a sponser of this board.
Setting the cam at 105 is 1 degree retarded from what the book says it should be. And retarding the intake cam gives more clearance. But that shim is .010" thick of stainless steel. And removing that takes .010" away right off the bat. So if you had .035" you now have .025" of piston to intake valve clearance. So you decide what you want to try and get away with. I'm running .028" You dont want to miss a shift with my setup. It could bend valves with stock springs. But then again I'm running the intake cam at 102++ without the block shim. Oh, just for the record... its not really a gasket its a stainless steel shim. It does have some kind of film on it thou.
As far as power? well that depends on how much power you were loosing from poor cam timing. It all depends on your combo. But you can pick up as much as 6 hp in some areas of the power curve.
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