suzukidude87
Expert Class
Posts: 228
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posted March 18, 2010 04:56 PM
zx12 stroker motor
Hello all, My brother baught a zx12 with a 5mm stroked crank, the motor should be like a 1420cc , well it was built by a well known and respected builder so I wont say any names, the bike never made to down the track for my brother, he had it on the dyno a few times, the previous owner put about 20 passes on this freshen up, previous owner was spraying the bike as well, it was determined on the dyno that there could be a head gasket problem, sure enough we take the motor apart and thats the problem,blown head gasket, funny thing is the bike would run fine sometimes and breakup other times, also the pistons are hitting the head, slightly, # 3 piston had a hot spot were the valve pockets leaned in slightly and the valves touched the piston, and same cylinder rod berring spun just enough to knock the tabs of the berring caps. didnt hurt the crank, question what kinda piston to valve clearance should there have been? piston to wall clearence was like .005 is this to much? looks as though the pistons are really rocking alot, also he has corrilla rods they seem to have alot of side to side clearence. anyone know what the limits are there, long story short this combo seems like it could be a piston eater. who has run this with any success? he may just go back with a stock crank. any advice !
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KZScott
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Posts: 7235
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posted March 18, 2010 09:49 PM
so was this a 3x5 or 4x5 motor? offset crank?
what was the squish?
Karl has run just about every 4x4.6 combo he will know more on the clearances
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01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
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entropy
Moderator
Posts: 8671
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posted March 18, 2010 10:38 PM
quote:
Hello all, My brother baught a zx12 with a 5mm stroked crank, the motor should be like a 1420cc , well it was built by a well known and respected builder so I wont say any names, the bike never made to down the track for my brother, he had it on the dyno a few times, the previous owner put about 20 passes on this freshen up, previous owner was spraying the bike as well, it was determined on the dyno that there could be a head gasket problem, sure enough we take the motor apart and thats the problem,blown head gasket, funny thing is the bike would run fine sometimes and breakup other times, also the pistons are hitting the head, slightly, # 3 piston had a hot spot were the valve pockets leaned in slightly and the valves touched the piston, and same cylinder rod berring spun just enough to knock the tabs of the berring caps. didnt hurt the crank, question what kinda piston to valve clearance should there have been? piston to wall clearence was like .005 is this to much? looks as though the pistons are really rocking alot, also he has corrilla rods they seem to have alot of side to side clearence. anyone know what the limits are there, long story short this combo seems like it could be a piston eater. who has run this with any success? he may just go back with a stock crank. any advice !
i have quite a lot of experience with exactly that build configuration. It sounds like the guy who sold it to yr brother spent a ton of money, got all the right parts, but just bolted it together, measured nothing.
If the valves have been hitting the pistons at all, head has to be freshened & those tagging valves are likely bad.
spun bearing definitely means the crank needs to get checked, very likely repaired.
Pistons rocking in .0050 clearance (should be .0035 max) means they are likely deformed = junk. They might be OK but definitely gotta be measured.
How is the cylinder block?
It took me quite a while to figure out how to build the 1427 configuration so it would live, its all about attention to detail. Along the way I cratered a buncha motors, some ending up just like yr brothers.
Mine lasts now, several years ago, I ran 8.790@159mph at drags and last year 222mph in measured 1.5mi so it now makes power and apparently lives.
You need a very good builder to help you with path forward.
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suzukidude87
Expert Class
Posts: 228
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posted March 19, 2010 09:35 AM
this is 5mm stroke with 1290 pistons, we didnt check the squish but will deffinately check all the clearances before this motor goes back together, the berring just moved enough to remove the tab that holds it in place, the crank jurnals look perfict, you can tell this motor was fresh, it just was not working good at all, we will be taking a closer look at it tomorrow, im thinking my brother is planning to go with a stock crank, our builder thinks the rods in the 12 being so short causes longgevity problems. another thing noticed the wrist pins were very tight in the pistons.
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KZScott
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posted March 19, 2010 08:35 PM
Ill trade you for a stock crank if yours checks out ok
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
|
kaw12
Expert Class
Posts: 172
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posted March 19, 2010 09:38 PM
whats so different about _stroker crank opposed to a stock crank?
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KZScott
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Posts: 7235
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posted March 20, 2010 01:11 PM
mostly the rod journal location on a weld up  .
a few pics here for ya http://www.bikeland.org/board/viewthread.php?TID=51424&FID=13
a billet may have slightly different locations for the oil holes (centered like a stock crank) but i dont think its really much if any of an issue unless you go huge (like a 10mm)
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
|
suzukidude87
Expert Class
Posts: 228
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posted March 20, 2010 08:14 PM
whats a good used stock crank worth ?
____________
thanks GOD for blessing us with bikes!
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KZScott
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Posts: 7235
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posted March 21, 2010 08:19 AM
not really sure $300-400? ron ayers has new ones for 800
i have one in my 1290 that Im pulling out for a 4mm in a couple weeks...
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
|
suzukidude87
Expert Class
Posts: 228
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posted March 21, 2010 03:05 PM
I have a perfect stock crank, just didnt know what they brought. KZ Scott if your serious about the stroker call me Bernard 330-812-7910
____________
thanks GOD for blessing us with bikes!
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KZScott
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Posts: 7235
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posted March 21, 2010 07:35 PM
im not looking to buy one out right, but interested in a trade, but you have a stocker so no real need for a trade i assume.
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
|
suzukidude87
Expert Class
Posts: 228
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posted March 22, 2010 04:20 AM
yeah we have lots of ZX12 parts laying around but thanks for the offer Scott.
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thanks GOD for blessing us with bikes!
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