addisonzx12
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posted July 31, 2002 06:46 AM
Actually, the head gasket turned out to be perfect. The steam cloud was from the cylinder wall. Odd thing is if it WAS a piston to valve clearance problem, how did the valves last over 10,000 miles of some pretty hard riding without breaking sooner? Just don't make sense.
  
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ZHooligan
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posted July 31, 2002 07:52 AM
I had a CBR1100 bored and stroked to 1380. The pistons were JE pistons. They rocked back and forth in the bores and and left thhe dings in the tops of the pistons. Eventually a liner cracked and the engine failed. Much as your issue. JE denied that this was a problem. MVR got WISCO to make him four custom pistons. Something JE claimed could not happen. As they say Wisco is a mass production shop and that they (JE) are the custom guys. Wisco's pistons had the proper valve pocket clearances, almost no taper to the piston where as JE's were severely tapered (went through three sets and all were the same. The results are after blowing the engine up three times it has now been running around on the street for two years. The difference was / is WISCO pistons instead of JE.
JE's response in all of this was that my engine builder (MIke Velasco) didn't know what he was dong and lacked experience in building high performance engines. I asked Freddy Spencer personally about this. He said whom ever I spoke to about this at JE was an idiot. JE said that their pistons are not ready to be installed when they are shipped. The pistons should be polished, the valve pockets measured and trimmed as needed, and the clay should be used to check for clearances. Asked about the rocking in the bore they said that the engine builder should prep the pistons for that potential. This is a no bull shit conversation with these guys! In the same conversation they talked about the heat treating of the pistons. How they are treated in / at three different levels and or ranges. The top is treated to one level, ring area another and the skirt at another. With all that said you are susposed to polish and grind on the pistons to prep them??? so much for heat treating!
When I purchased my 1270 kit from Muzzy I was skeptical because of the JE pistons. Needless to say I examined the pistons very carefully. Either Muzzy influenced JE to do a decent job, or Muzzy prep the pistons prior to shipping or I got lucky. Because the set I received actually seemed to have been prepped properly, the taper was within tolerance and the valve pockets fit.
The long and the short of this whole story is it is possible that your valves were tapping ever so slightly and eventually you had a failure. These big bore bikes will run when they shouldn't. My 1380 XX on the 2nd blow up made some really bad noises at speed, stuttered and then made some really shitty clattering noises. I was along ways from home so I rode it. When we got it in the shop it would still start and idle. When we took the valve cover off, with a flash light you could see the crankshaft in the four hole. Usually there is a head, valves, piston and rod there! There were some piesces there but not enough to block the view!!!!
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swft
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posted July 31, 2002 07:52 AM
Maybe the 3mm bore just flat took too much out of the walls?
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ZHooligan
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posted July 31, 2002 08:16 AM
The cyclinder wall failed on the third motor when we went even bigger! We went bigger because of the damage to the cyclinder from the 2nd. blow up. And that bore is in a number of XX making up to 450 hp with turbos. Of course they a drag bikes that are not everyday riders.
And if you look at the pistons out of certain 1270 we both are familar with you will see where there has been shall we say no clearance between the valves and the pistons.
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To those who do not count their life in years, but in how life
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future; -- Youth is forever.
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swft
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posted July 31, 2002 08:46 AM
 Edited By: swft on 31 Jul 2002 10:03
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RobMuzzy
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posted July 31, 2002 09:30 AM
The only 1270 that I am aware of is the kit offered by muzzys. With a stock height cyl. head (not milled)there is 1.5mm intake and 2mm exhaust piston to valve clearance. MUZZYS has sold hundreds of these kits and it has never come to my attention that any customer has had a problem with either cyl. cracking or not enough piston to valve clearance. Remember we use these same products in our own racing efforts, wich include Drag racing,Top speed runs, and Mini sprint applications. We have ZX-12 engines that are 1427cc normally aspirated, 1225cc Turbo charged, and 1270cc on Nitros. If there is a reader on this board that has had a problem with a MUZZYS 1270 kit please contact me at muzzys.com.
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swft
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posted July 31, 2002 09:43 AM
Thanks for speaking up, Rob. I was trying to make that point, but wasn't having much luck with it.
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ninja12
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posted July 31, 2002 10:34 AM
I think muzzy RECOMMENDS the adjustable cam sprockets with the 1270,
but are they REQUIRED?
What is the risk if you don't, less power or engine damage?
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addisonzx12
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posted July 31, 2002 11:29 AM
Please note, we are talking about 3mm over JE pistons 1287cc not the 1270 kit from Muzzy.
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ZHooligan
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posted July 31, 2002 01:19 PM
As I stated above Rob, I look at the JE pistons your kit supplied and they were properly prepped unlike the JE pistons sold to Joe Dokes off the street.
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future; -- Youth is forever.
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swft
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posted July 31, 2002 02:14 PM
Who's Joe Dokes? Does he work for Superbike Mike? 
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