jerry coomer
Novice Class
Posts: 43
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posted October 23, 2005 05:16 PM
strocker crank longivity
will a welded up stroker last in a zx 12? and is it even worth messing with?
  
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kawachan
Pro
Posts: 1031
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posted October 23, 2005 05:34 PM
If heat-treated right, yes they will.
Krexken had one that I personally saw go 159ish on motor. He rode it everywhere and raced/rode it all the time. Still running as far as I know.
MadMike had lots of passes on his too.....
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RED NINJAS RULE!!
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trenace
Needs a job
Posts: 3056
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posted October 25, 2005 04:30 PM
There have also been very many short-lasting results.
If anything it seems to me that the number of guys reporting a long lasting result (by street standards of mileage, as opposed to "I got a full season out of it") is considerably less than the number that have had failures at rather low mileage.
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krexken
Zone Head
Posts: 732
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posted October 25, 2005 04:38 PM
I have yet to hear of a stroker with a crank failure in a 12. Maybe bearing failure but I believe that's totally unrelated. Yeah, my old bike still runnin. Almost 5 years later. No rebuilds. Just a little nitrous every now and then. LOL
What's up Chan Chan? My old track is closed. WAHHHHHHH!
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trenace
Needs a job
Posts: 3056
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posted October 25, 2005 05:06 PM
 Edited By: trenace on 25 Oct 2005 18:35
Well, if totally unrelated then it's quite a coincidence how high the failure rate has been. There's also a direct possible causal relationship, namely that when one increases stroke, piston accelerations increase, which increases bearing load. There is also an increase in peak piston acceleration -- kind of a whiplash effect -- associated with reducing the rod/stroke ratio, which with the stroker goes to a regime generally not considered so suitable for a performance engine and certainly not preferable, namely down to the mid 1.4's range.
Imagine a 350 Chevy with 5.06" rods, and that's the kind of severe short rod situation we're talking about with force-fitting a 60mm stroke into a ZX-12R engine, if that helps picture it. It is not within any engineering standards for a production motor at that point, or certainly not a high-performance motor anyway.
However, I can't disprove that it might not be pure coincidence that the failure rate within fairly modest miles (by most street standards) is so high. Quite a coincidence though if so. Certainly stock motors aren't suffering bearing failures at remotely that rate. If they were we'd have 1000 reports of it or more, given the number of members on this board.
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rac4it
Needs a job
Bergie
Posts: 3009
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posted October 25, 2005 05:49 PM
99% builder, 1% parts.
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NOX
Needs a job
PMRA / TMRC Super Street 4022
Posts: 3745
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posted October 25, 2005 09:51 PM
It is true that short stroke, big bore is better, but at some point you run out of bore. I would think a beefier low end, stock stroke, cams, and a 1317 would be a great package, and could be turned at a higher rpm for more power. At least that is what I am wanting to do right now.
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dougmeyer
Needs a job
moderated
Posts: 2713
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posted October 28, 2005 06:20 PM
Amazing insight, Bergie.
D.
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johns
Expert Class
Posts: 205
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posted October 30, 2005 05:47 PM
Edited By: johns on 30 Oct 2005 17:49
Jerry, where are you from, you have to be the Jerry Coomer I know from Louisville?
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2006 ZX-14 (sold)
2012 ZX-14R (Brock's Perf. project bike Louisville Slugger)
2013 Honda VFR1200F
2003 124 C.I. H.D. Super glide
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Hells Dark Lord
Needs a life
living life, and loving it.
Posts: 7981
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posted November 01, 2005 06:46 AM
dam lots of Louisville guys on here...bhut I never see those Zx12's out whats up with that?
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When in doubt, lean farther and go faster....
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bossman12r
Zone Head
Posts: 513
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posted November 01, 2005 01:14 PM
The only thing I lost in louisville, Ky was my ex wife.
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gen 4 zx10 is fast
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johns
Expert Class
Posts: 205
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posted November 02, 2005 01:47 PM
Jerry Coomer
If this is the Jerry Coomer I know from Louisville he owned a couple of very fast Hayabusas and some very fast Chevrolets. Last I heard he got out of dragracing bikes.
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2006 ZX-14 (sold)
2012 ZX-14R (Brock's Perf. project bike Louisville Slugger)
2013 Honda VFR1200F
2003 124 C.I. H.D. Super glide
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