canadamaxxer
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Posts: 1090
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posted November 28, 2004 04:58 PM
Stroker cranks
I was reading on another forum about reliablity issues with stroker cranks (breaking after 4,000 to 8,000 miles). Is this realistic? I have to assume that this is with weld up strokers, but why should they fail as a reuslt of the weld up? Making stroker cranks is not anything new, and repairing cranks by welding and regrinding has been done for decades. Why is this so different.....or is it?
  
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Ra12r
Zone Head
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posted November 28, 2004 05:28 PM
There isn't any issues with a modified crank. The busa and the GSXR 1000's are 60mm OEM (5mm for the zx12) and are not considered stroker. So frankly it is more of an academic arguement between folks. All I can say it that the motor runs much better with the crank modified.
Don't confuse racing reliability vs street.
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canadamaxxer
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posted November 28, 2004 06:16 PM
Here is the forum topic I stumbled across: http://www.zx-12r.org/phpBB2/viewtopic.php?t=28716
Here is the quote in question:
(snip)
Allen, I was talking to Blais today and discussing your best options if indeed you needed to rebuild the motor.
He said that the 1375 kit is a great idea...IF you don't plan on riding it on the street all the time. He said the crank only lasts about 4-8k miles before it snaps and destroys the motor. So if you want it to be a trailered bike...go for it...if you want to ride it around on the street....go with his suggestion which is...
1270 Muzzy kit
Muzzy Race cams
Full headjob
Custom remap (would be free of charge)
and a 50 shot of NOS.
He said this combo would make for a RELIABLE 200+rwhp SAE on motor and 250rwhp SAE on spray. This combo could be run all day everyday without hurting the motor.
(snip)
Is this simply one dude's opinion or is there validity to this? I have never heard of a proper done stroker crank failing...until I saw this.
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TurboBlew
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posted November 28, 2004 07:08 PM
Well.... there is the problem.... Blais building the shit....lol.
NONE OF HIS SHIT WORKS... period. And its not brand specific either. He's fucked up alot of BUSA motors too.
In short... the guy cant build anything that lasts or goes fast. He (Blais) just happens to be in an area (South FL) thats full of thick wallets and small brains.
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TurboBlew
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posted November 28, 2004 07:12 PM
Oh, and you can poke around Dales site to find pics of Blais "world killer" ZX12.
Damn thing couldnt get past 196mph at sea level. He was a laughing stock when a stock bore/stoke stroke/ stock wheelbase Hayabusa went 5mph faster than his $40,000 Ohlins shod/custom bodywork ZX12 at 9/10ths.
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canadamaxxer
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posted November 28, 2004 07:16 PM
Oh, ok.....That is very good to know. I just wanted to get that clear based on the experience of our members. I have a crank sitting ing a box in my garage that is patiently waiting to become a stroke......and I want to know if I was buying into a timebomb. Good also to know that Blais is not a credible builder....I had never heard of him.
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TurboBlew
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posted November 28, 2004 07:29 PM
I know Entropy posted the contact info for the machine shop that did his crank in less than a week.
How much of a stroke were you going to go on the motor?
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canadamaxxer
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posted November 28, 2004 07:54 PM
I am thinking 4.6mm. I just want 1375cc at the end of the day. I already have the 1270 kit, and am thinking of doing the stroker with a spacer plate so that I don't have to cut the pistons down (I intend to run a fairly big shot eventually as well, so I want the dome thickness). The spacer technically should give better connecting rod angularity, which may actually show real gains, if not sound really good while having a pint with the boys.
I think the place that Entropy had fix his crank (and they will see my business also) is Marine Crankshaft.
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zrxdean
Needs a job
Posts: 2225
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posted November 28, 2004 10:04 PM
I don;t have any personal experience, but I was told my Muzzys, Falicon, and APE that stroked cranks, 4mm or more, will eventually crack. The additional leverage of the con rod on the crank leads to failure. Doug Meyer suggested no more than 3mm for a street motor, if I wanted to drag only, I could go to 7mm on the ZRX, but expect to replace it once a season or thereabouts.
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entropy
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posted November 29, 2004 12:29 AM
 Edited By: entropy on 29 Nov 2004 00:33
CANADAMAXXER,
I HAVEN'T HEARD OF A SINGLE CRANK, STROKED OR NOT, WHICH HAS (fukken capslok) had a cracked or completely failed journal or throw.
I have heard (and experienced 2 personally) of plenty of toasted motors due to failed bearings (oil starvation). Not the stroker's fault.
I wouldn't think twice on running a stroker on the street; Au contraire, IMO it's best single mod you can do for the 12.
The good hp the 1270 has at 10,500rpm is rarely experienced on the street; whereas the stroker's lo rpm hi hp is experienced every time you twist the wick. night n' day difference!!!!!! 
Marine Crankshaft is likely to take more than a week on welding up a stroker, but that's sure as hell where i'd take it! Give em a call.
Good luck!!
BTW: a 1375 Zx12 has a 60mm stroke, a STOCK Busa has a 63mm stroke...
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bossman12r
Zone Head
Posts: 513
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posted November 29, 2004 07:04 AM
What about the heavy 02 crank vs a 00-01 crank. Would it help an 02 motor to have an 00-01 lighter stroked crank in it or the heavier 02 stroke crank?
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gen 4 zx10 is fast
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dougmeyer
Needs a job
moderated
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posted November 29, 2004 11:45 AM
My comment to Dean regarding stroke length/reliability was in reference to ZX/ZRX-11 cranks only.
Entropy has it right- no breakage, only bearing failures due to oiling issues.
Doug
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bossman12r
Zone Head
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posted November 29, 2004 12:11 PM
Doug, what about the 02-00 cranks?
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gen 4 zx10 is fast
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dougmeyer
Needs a job
moderated
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posted November 29, 2004 01:26 PM
There's really no downside to the heavier 2002 crank, especially for drag race applications. Stroking any crank changes the rotational mass/moment slightly as well. Keep in mind that the alternator stator/rotor also differs between the early and late units and further allows you to run a slightly heavier or lighter set-up.
Crank weight (mass) effects the rate that the engine spins up (or down i.e., resistance to "bogging" at launch)
Doug
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bossman12r
Zone Head
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posted November 29, 2004 01:29 PM
So an 00-01 will not just bolt up to an 02 then.
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gen 4 zx10 is fast
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ninja12
Needs a job
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posted November 29, 2004 05:19 PM
Edited By: ninja12 on 29 Nov 2004 17:21
yes it will.
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ZXLNT
Needs a job
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posted November 29, 2004 09:45 PM
Bossman I have the flywheel for that crank as well..
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bossman12r
Zone Head
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posted November 30, 2004 04:57 AM
Time to expand on the christmas list  Now if santa will leave me some money for a gift
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gen 4 zx10 is fast
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