trenace
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posted August 07, 2004 09:37 PM
 Edited By: trenace on 7 Aug 2004 22:39
JE pistons, or others: round at operating temp?
Are JE 1270 pistons designed and produced as round at room temperature; or are they machined in a very precise way very slightly out of round at room temperature but designed to come to essentially perfectly round at operating temperature?
I don't know if that is an issue dealt with by JE, Wiseco, and MTC or not but hope someone does?
Yes, I know I could ask JE if they do this or can do this and if no one happens to know already I'll do so! 
Thanks!
  
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entropy
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posted August 08, 2004 01:34 AM
trenace,
whoa! there's a cool question!
go on suzukihayabusa.org, ask the question to "speedking" aka John Noonan, JE's MC division manager and frequent contributer to sh.org forum. REALLY good guy and top end maniac.
He gave me a tour of JE's mfg facilities earlier this yr and I have his work # if you want it.
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VincentHill
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posted August 08, 2004 05:07 AM
Most pistons are Oval shape (Cam Ground) and are also pirimid shape also smaller at the top than at the bottom. The thinhing is a little blow by is good in the cold start up to take some of the shock and pressure away while the oil warms up and everything else does. The taper from top to bottom is because the heat at the top is a "LOT" greater at the top (Which causes swelling) than at the bottom. These are the reason they give you a measuring point near the bottom for clearance because all things being equal, if that point is correct, then the expansion of the piston will generally be controlled at a rate best for that engine's application (NA, NOS, Turbo) That is one of the reasons you need different pistons for these applications because the piston maker needs to change the profile to handle the heat.
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entropy
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posted August 08, 2004 06:53 AM
hey VH: how is yr re-build going??????
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VincentHill
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posted August 08, 2004 11:59 AM
quote:
hey VH: how is yr re-build going??????
CP Is making my pistons as we speak. I found a "Stupid" I did to myself and had to take the case apart to fix it! I put the step washer behind the clutch Hub on backward and could see where it had heated the bearing so i am replacing that bearing and the Countershaft bearing while I am at it. I will also look at the back cut of second gear!
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trenace
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posted August 08, 2004 12:13 PM
Thanks, Entropy, that's good information: I didn't know John Noonan was online. Definitely the way to get the authoritative answer quickly -- too often just writing or calling a company on the phone gets people that don't really know and it can be hard to get information.
Vincent, thanks also for your as-always top-notch information. It sounds like you're saying, not necessarily specific to these JE pistons, that the aftermarket manufacturers as well as the OEM do indeed at least often pay attention to this issue. I knew the OEM's did, but it's obviously a trickier machining to do it this way, and it's been said (when responding to complaints of others about failures of pistons in the price range of a few hundred bucks) that well if you want a top-notch piston you have to pay more, so I was wondering if maybe this was the difference, or one of the differences, between a pricier piston and your general aftermarket piston.
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VincentHill
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posted August 09, 2004 04:09 AM
My thought is some makers supply a piston and you use it anyway you want other than the way it was intended and some tell you up front that the piston was made for 1 thing period (Like MTC only makes Turbo Pistons for the 12) Yes the machining has 2 problems, the Knowledge to know what it is doing inside your engine and the machines to make the piston as designed!
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entropy
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posted August 09, 2004 05:53 AM
VH:
you put yr finger on it.
The tough part:
"Knowledge to know what it is doing inside your engine..."
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psycho1122
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posted August 09, 2004 07:27 AM
VH;
I strongly suggest NOT running "back-cut" or "undercut" gears in the trans.
This weakens the "spokes" or the "windows"...ESPECIALLY on the offset 2nd, 3rd and 4th gears.
I have had 3rd gear failure myself!!
Robinson Industries makes billet gears for the 12 
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VincentHill
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posted August 09, 2004 01:45 PM
quote:
VH;
I strongly suggest NOT running "back-cut" or "undercut" gears in the trans.
This weakens the "spokes" or the "windows"...ESPECIALLY on the offset 2nd, 3rd and 4th gears.
I have had 3rd gear failure myself!!
Robinson Industries makes billet gears for the 12
I understand what you are saying and have seen some people go crazy on the back cut to the point that the dogs look like pirimids. What I am doing is taking the dremmel tool in a little fixture I make and with each gear on the shaft for trueness one at a time slide them over to the cutting wheel. On the inside edge I may take .005 or as much as .010 until the all match perfectly (Same bottom width and top width. It is very easy to mess the gears up ny having one cut a few .001 more than another one which puts twice as much stress on the next dog. I think this is waht causes the dogs to break. Sometimes all that is needed is the abrasive rubber wheel to polish the ends of the dogs so that they will "Slip" past the ends and into gear better.
From the first time I tried to do this and back cut both sides and could not get ny Bighorn out of gear if i let off the gass in gear, I havelearned that little and nothing work real well!
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trenace
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posted August 09, 2004 04:29 PM
quote:
Robinson Industries makes billet gears for the 12
Do you have contact info?
I tried googling it but only found companies that seem different, for example a manufacturer of fans and industrial blowers.
Thanks!
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psycho1122
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posted August 09, 2004 09:05 PM
(www.robinsonindustriesinc.com)
Billy even has pics of the billet gears on the site
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