Mikkel
Novice Class
Posts: 57
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posted July 04, 2010 03:14 AM
Piston damage
The #2 piston in my 1270 engine gave up, a piece around the exhaust valve pocket cracked off, the missing piece bent the exhaust valves, one valveguide shows craks and #1 and #2 rod bearings are bad, the rods don´t spin freely. I haven´t split the cases.
Looks to me like the squish was set too tight. I recently changed the oilpan from stock to a Koenig. The bottom end of the engine has never been opened, I just installed a used 1270 piston/barrel kit i bought from Jim Y2KZX12R and have been using the bike for dragracing for over a year. Everything else is stock exept I left out the base gasket. Squish and PTV clearances checked out fine but perhaps i haven´t been careful enough! I´m thinking of getting another engine and fitting the 1270 big bore if I can find a good piston (i´m on a tight budget!), it´s the 85,4 mm JE. Has anybody got a good piston or an engine? The cylinder is still good. Email: larsvegas@vip.cybercity.dk
  
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ZRXDean
Needs a job
Posts: 2225
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posted July 04, 2010 04:30 AM
I'm just guessing, but could detonation be part of the problem? What fuel were you running?
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KZScott
Needs a life
high on speed
Posts: 7235
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posted July 04, 2010 05:14 AM
did you prep the pistons any?
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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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Stuart Racing
Zone Head
N.H.R.A . Dragracing.
Posts: 999
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posted July 04, 2010 05:46 AM
Thats the way they should look....Good job....
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Life in the Fast Lane..........
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kawa74
Expert Class
Posts: 226
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posted July 04, 2010 07:22 AM
I believe you said in your post , recently changed OIL PAN , I would look at oil pan real close did you prime oil pump ? fill oil filter ? Sounds like you got AIR in oil lines , starved bearings ,, wiped bearings , clearance opened up , let pistons hit head , IF squish is too tight you would know on first pass , crush rings , smash bearings , bend rods .
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"I have never met a man so Ignorant that I coun't Learn from him"..."Galileo"
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Mikkel
Novice Class
Posts: 57
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posted July 04, 2010 10:51 AM
I did sand the sharp edges. I use 99 octane pump gas (that is 94 in US measure!) I noticed that the #2 piston top is cleaner than the other pistons, that is also the case on the stock pistons, I didnt´t notice that when I pulled them out. Maybe a bad injector that could cause detonation? Must have the injectors cleaned and checked. The plugs look the same all 4 (ok). I did fill the oilfilter but didn´t prime the pump. The dummy light went out immediately at the engine startup after the oilpan change and it hasn´t flickered at any time to my knowledge. I guess the light goes out at a very low pressure so that doesn´t necessarily mean that the pressure is ok. Oil level is at the top of the glass. I also think that too little squish would have shown ealier, but it looks to me as if the pistons have signs of barely touching the head. When I measured the squish it was ,031". Isn´t a tight squish supposed to help reduce detonation? Has anybody got some parts I can use?
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dougmeyer
Needs a job
moderated
Posts: 2713
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posted July 04, 2010 12:25 PM
Got a picture of the broken piston and the bearings. We can pretty much tell you the cause if we can see the bad parts. Your piston prep looks great.
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It's not that I think you're dumb, it's just that so much of what you know isn't true....
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Mikkel
Novice Class
Posts: 57
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posted July 04, 2010 12:47 PM
Doug, I have emailed you pictures of the piston, the bearings are still in the engine.
Thanks for all the reply!
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KZScott
Needs a life
high on speed
Posts: 7235
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posted July 04, 2010 12:50 PM
Doug, those are my pistons. thanks 
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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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