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ZX12 Big Bore kits ?????

This is a discussion on ZX12 Big Bore kits ????? within the ZX-12R forums, part of the Kawasaki Motorcycles category; I currently own a Yamaha Banshee Powered by a ZX9- R motor (my daily driver) & I'm looking into stuffing a ZX12 motor in a ...


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Old 10-28-2003, 05:48 PM   #1
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From: Omaha, NE
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ZX12 Big Bore kits ?????

I currently own a Yamaha Banshee Powered by a ZX9- R motor (my daily driver) & I'm looking into stuffing a ZX12 motor in a Banshee frame also (my dragster) & was wondering what big bore kit you guys would reccomend? I would like something in the 200rwhp range on race fuel only. I called Muzzy today and was told I can accomplish this feat with the 1270 & 1317 big bore kits. I'm looking to get your opinions on this. I'm looking for the most reliable & affordable setup as possible. And I do not want to run nothing more than race fuel.



thanks
Jay
   
 
Old 10-28-2003, 06:14 PM   #2
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They claim 203 hp for their 1317 kit, at $2850.

Subtract 5-6% to account for the fact that their dyno reads in units of Muzzy mini-horses rather than real ones -- or at the very least if I'm too cynical reads in STD hp rather than the more accepted SAE hp -- but add about that much back in again for oxygenated race fuel, and that winds up right around 200 hp.

Also sounds about right for other reasons.

200 hp sounds a little high for nothing but 1270 pistons, pipe, and mapping, unless talking about figures off a happy dyno.
   
 
Old 10-29-2003, 07:49 AM   #3
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Thanks for the input. I'm just trying to make sure when throwing down this kind of coin that I'm getting the best bang for my buck. 8)
   
 
Old 10-29-2003, 08:07 AM   #4
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From what I've heard, it takes some breathing work to get 200hp out of a 1270. Here's some interesting charts:

http://www.leesperformance.com/dyno.htm
   
 
Old 10-29-2003, 10:48 AM   #5
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Definitely some interesting charts there. The 1270 with cams, throttle bodies and
ported head looks very satisfactory, probably even moreso with an Akrapovic :D

Decisions, decisions. The same power could be achieved with stock cam (giving more
low rpm pull, better gas mileage, more overall "driveability" probably) by going to a
big block and billet stroker, but that indeed would be a lot more money, mostly just
to accomodate lazy moments at low revs. This 1270 set-up definitely would seem
to provide, for me anyway, completely satisfactory midrange and top-end rush:

   
 
Old 10-29-2003, 11:42 AM   #6
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I've been thinking about what could be accomplished with a stock bore. The 1270 is 6% bigger than our 1198. Assuming an equal power discrepancy, that brings you down from 210 to 197-ish. The 1270 also has a higher CR, though, 13.6 as opposed to the 12.2 of stock. JE offers stock bore 13:1 pistons which (they say) would only require deglazing the cylinder rather than a replate, but would still be .6 down on compression. I don't know if Shierts (or anyone else) could get that back by shaving the head. Plus, you'd give up some of the bottom end and mid range you're after.

You say a big block/stroker setup would be a "lot more money", but I'm sure Lee's breathing magic doesn't come cheap. :wink: There were some prices quoted in dragbike.com's GSXR1000 buildup, though. The whole motor was like $5000, but that was 200hp out of 1052cc (I think).
   
 
Old 10-29-2003, 01:26 PM   #7
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Well, if from Muzzy's, the big block is $2850, and the billet stroker crank is $3700.
All for the sake of an extra 3.7% displacement increase relative to the 1270 from
the boring, and a further extra 3.8% increase from the stroke increase -- which doesn't
necessarily fully translate into equivalent percent increases in hp.

Headwork has always been in the picture, so it isn't a savings of either doing that
or not. I hadn't known about Lee's before this. It looks like their price is about
$800-$1200. I'd been impressed by the results claimed by
http://www.cylinderheadshop.co.uk/perftune.html and still so far am probably leaning
that route for the heads.

The throttle body boring is probably a good idea in either case.

So the cost comparison is really between Lee's cams, vs the billet big block and
crank, or vs combining them all... for sure the first is a big savings!

It's also interesting to note that unlike ZX-12R dyno charts with stock cams, the
Lee's dyno chart even on the pump gas not only is pulling all the way to the limiter,
but actually has peak hp there, the hp curve still climbing, and with the torque not
falling off too badly... this suggests that if the rpm limit could be raised, another
10 hp or so might be found at 12,500 rpm with stock stroke. Which would eliminate any
motivation to increase stroke with the billet crank, as essentially if this is the case,
the stock stroke could produce the same max power as the 60 mm crank, as I wouldn't
spin that crank past 11,500.

However, how do you increase the rev limit, short of going to the Muzzy's ECU? Which
overall I do not want to do.

Anyway, these were the first graphs that made a cam change seem really promising. The
only report I'd seen on a cam change was one over on bikeland, reporting something
like only 3 or 4 hp for the trouble, and with no specific information on how much was lost
at lower revs. With this chart, it was pretty clear that the loss was reasonable. :D

And on the stock bore concept: agreed, stock bore in and of itself should cost no more
than about 5.7% power relative to 1270 due to that percentage of displacement
increase, as a reasonable approximation -- could be a little less or more depending on
whether shrouding is significant and that sort of thing, but this should be close enough.

I myself (unless in a racing application, which isn't the case for me) wouldn't swap
out good 12.2:1 pistons for 13:1. On a thermodynamic basis, which admittedly isn't
the full story but usually is close enough, that 0.8 point increase is worth only 1%. I'd
stick with stock pistons rather than swap out for just that.

So from that standpoint, possibly, the 211 hp on pump gas reported above, could
come out as an estimated 194 hp SAE with stock pistons, figuring 5.7% loss due to
lesser displacement and a further 2% loss from lower compression relative to
the 1270. Hardly bad, and quite possibly enough for 200 mph if say MR9 is used, as
that might give an increase to about 210 hp.

Still, I'd go for the 1270 :D
   
 
Old 10-29-2003, 08:09 PM   #8
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I've visited the link you quoted before. Are you in the UK?

I was hoping you'd give me a clue as to how much the compression difference would be worth.

Seems that some think that the 12 is restricted on the exhaust side:

http://www.zx-12r.org/phpBB2/viewtopic.php?t=14690 (all the way down)

I dunno. I might have to take visit to N.C.
   
 
Old 10-30-2003, 03:17 PM   #9
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i have a 1270 and it only makes 197 on motor
   
 
Old 10-30-2003, 04:25 PM   #10
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Unfortunately, most of the time, more than one thing gets changed at a time so it's hard to pinpoint how much each thing was worth, but where the only change is compression ratio, or compression ratio with just a little displacement increase, and compression ratio was reasonably high to begin with, it seems that top end power increases are never very much. Just from observation.

In an older engine that was say 9:1, knocking that up to 11:1 is a pretty noticeable difference. But say 12.2:1 to 13:1 or 13.5:1, that's not the impression I have.

There's an equation for it which is based on theory of heat, and the calculator is at that link. Sometimes it seems like the midrange can be improved more than that, so I guess that isn't due to better utilization of heat but improving flow somehow.

I'm not in the UK -- I'd have to send out to that company if I went that route. It just sounds promising, not only from the result they report, but it sounds as if they definitely have some very high-end experience and are working at a top level. Just a personal confidence thing, I'm not worried they'd hurt power while increasing flowbench numbers as can happen with full porting, and maybe they might do an exceptional job. If I got results like they say from just the head and pipe -- stock displacement, stock cams etc -- it would have to do really well with more work! :D
   
 
Old 11-01-2003, 10:20 PM   #11
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From: Scottsdale, Arizona, USA
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Fascinating discussion!

Trenace, could you give me any good reference/information about the difference between stock and aftermarket camshafts? I hope to find a before/after dynamometer chart with the camshaft change only so that I can see just how the torque curve changes.

I agree that "only 3 or 4 hp for the trouble" is nothing much at a 200 HP level. "how much was lost at lower revs" is my other concern; words are rather vague, here - I want pictures!


Grinder
   
 
Old 11-02-2003, 09:38 AM   #12
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Unfortunately, I don't have any more information than this on comparative dyno
figures for the 12R with aftermarket cams.

I came to the conclusion I did on the Lee cams still offering reasonable low end
performance based on the chart showing 70+ ft lb all the way down to 3500 rpm. With
stock cams, I'd guess that would be something like 75 ft lb or a touch more.

So basically, you're trading off modestly below about 6400 rpm, in favor of really
coming on the cams from that point on.

All depends on application... from one viewpoint, there's still plenty of torque at
low mid rpm for ordinary street riding at those revs, since after all if you really want
hellacious power at that moment, what are you doing at those revs anyway? and
you get a great 6400 - all-the-way-to-the-limiter powerband.

From another perspective, you don't pull quite as hard at say the 3000's and 4000's
as you would with the stock cams, which depending on application might not be a
price worth the extra top end rush.

I wish charts had been posted for the Muzzy cams but I haven't seen them, only
the figure for the rather limited top end gain, and general statement of reduced power
elsewhere.
   
 
Old 11-03-2003, 06:17 PM   #13
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From: Scottsdale, Arizona, USA
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Trenace,
Thanks for your quick reply.

(Thanks for helping me think, and please correct me.)

[Lee's is a 1270cc]

I've got to do this the old-fashioned way, then? I have the torque curve from some magazine several years ago; I have found the various magazine dynamometer curves to be close enough to each other - both the the 12's and the dynos (maybe the same dyno?).


>" . . . Lee cams still offering reasonable low end performance based on the chart showing 70+ ft lb all the way down to 3500 rpm. With stock cams, I'd guess that would be something like 75 ft lb or a touch more."

You know, I digitized my magazine torque curve (by hand/eye!) and I read 65 at 3,500 for the magazine's 12.

Most interesting!


">So basically, you're trading off modestly below about 6400 rpm, in favor of really coming on the cams from that point on."

(Ha, ha, "really coming on" is the point of going Kawasaki, I believe.)

Dang!, I have no convenient way to overlay the curves. At 6,500, I read about 97 on Lee's vs. about 87 for the magazine's 12. Yes!

This seems to be one of those magical situations (like a 513 CID in a Camaro?) where the bigger heads and the bigger cam work synergistically.

I see no RPM at which the torque is less with Lee's.
(Did I just answer my own question?)


>" . . . still plenty of torque at low mid rpm for ordinary street riding at those revs, since after all if you really want hellacious power at that moment, what are you doing at those revs anyway? and you get a great 6400 - all-the-way-to-the-limiter powerband. "

>"From another perspective, you don't pull quite as hard at say the 3000's and 4000's as you would with the stock cams, which depending on application might not be a price worth the extra top end rush. "

The only slightly peakier torque curve might accentuate the illusion of a weak low end; still, I see higher torque at every RPM with Lee's from 3,500 (where the Lee's curve started) on up to the 'artificially low' 11,500 RPM rev limit.


When we read the Lee's curve, we need to be careful to get the correct curve, where they cross over! They are almost the same color on my 16,777,216 color computer . . .

Note that the "96.9" on the torque curve is _not_ at all the peak!; it is merely at the ~11,500 RPM cursor. The torque peak(s) at around 7,500 RPM to 9,000 RPM is at about 108 (that horizontal line is really the 200 HP line).
Call this 20% more than the OEM ~91 at 7,500 RPM? Extra neato!

BTW, at the end of the chart - a mere 11,500 RPM - the torque curve is level and the HP curve is pointing up sharply.

As mentioned, Kawasaki likes to rev.


Grinder (I answered my own question!)
   
 
Old 11-04-2003, 06:08 AM   #14
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Cool thread... 8)
   
 
Old 11-04-2003, 12:18 PM   #15
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From: In front of the EyeAbusers
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I am making 189 SAE with a 1270, and a Muzzy.
   
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