supra5677
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posted April 28, 2007 06:05 AM
oversize exhaust valves zx12r
Someone posted on here that they netted 9RWHP with the intake cam on the exhaust side and 1mm oversize exhaust valves..Can't seem to find the post again.. Does anybody know who manufacturers these vavles.. Since i'm down might as well do it right..
suora
   
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entropy
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posted April 28, 2007 06:58 AM
Kibblewhite is where i get all my valve stuff (except fine shims).
you doing oversized exh valves and not oversized intakes???
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supra5677
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posted April 28, 2007 07:20 AM
the stock 33.4 mm valves are larger than the busas.. seems that its hard to get good exhaust flow out of the stock head from what Iv'e read from other posts.. I think Y2k said that the stock valves ( intake )would not become a restriction until like 14,000 rpms...
supra
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supra5677
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posted April 28, 2007 07:51 AM
how did you get valves from kibblewhite, they dont sell to the public?
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dougmeyer
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posted April 28, 2007 07:23 PM
Oversize valves will not result in more power on a 12. Waste of time.
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ZXLNT
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posted April 29, 2007 03:49 AM
Doug was that some info gleaned from tuning the Pro Stock 12R??
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dougmeyer
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posted April 29, 2007 07:21 AM
I did not work on the Muzzy prostock bike.
But, that is "info gleaned" from pretty direct knowlege of quite a bit of R&D on the 10, 11, 12 and other Kawaskis. Generally speaking, Kawasaki is amazingly good a designing their engine combos, especially in this area. I personally tried big valves on the 10 and 11 and saw no improvement. I am familiar with others who tried oversize valves on the 12 and also saw no appreciable improvement.
Here is why:
The whole idea of "big valves" being a easy route to power is a hold over from two valve engines where increased valve area and good flow at low lifts was really tough to come by. It's not the same in 4 valve setups where you've already got a huge amount of valve area per bore size.
There is quite a bit to be gained however, from doing a precision 5 angle valve job and bowl port to make maximum use of the valves you have.
Doug
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Y2KZX12R
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posted April 29, 2007 03:58 PM
Yea I would agree Doug on a stock 1199 cc engine.
But I would think 1375 or bigger engine spinning at 13k-15k could make use of bigger valves.
On a big cc engine at high rpms, bigger valves would depressurize the port quicker, no?
The 12r's valves are larger than a busas even thou the engine is 100cc smaller. I believe this to be the reason why. It aids power at higher rpms the quicker you drop the port pressure.
On the other hand those those big valves hinder power on valve closing at low rpms due to the reduced velocities and the reversion effect.
But for a drag engine or especially a top end run bike for the texas mile or bonneville thats not a concern.
I havent dynoed a big valve 12r of any displcement yet, so I,m just going by seeing what software simulation trends are on the 12r and busa engines.
Sometime this summer I'll be past the development stages of the big valve Busa head and have one for testing. I'm not so sure i'll do one for a 12r. The cylinder block skirts are too short, and the crankcases have little room for more than 60mm of stroke and the bores are allready maxed out.
The 14 will be a good canidate. Anyone got a 14 head they dont need?
Doug whats your take on a big valve 14 displacing 1600 cc or so? Think it could use bigger valves if its revved above 13k?
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MadMike
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posted April 29, 2007 08:49 PM
I heard a rumor that Bob Carpenter said there is a lot of room for improvement in the 14's head, unlike the 12 head was super good from the factory...
but you know as with any salesman they have to sell their product...
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dougmeyer
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posted April 29, 2007 09:56 PM
Good question Y2. I haven't given much thought to the 14. I'd be interested in what the software says..... It won't be long before there is some real data out there.
Doug
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TRNorBRN6001
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posted April 30, 2007 01:56 PM
Doesn't Mad Mike sell them Kibble valves? Whatever you decide, small or big valve you might as well put some nice ss valves in. I have heard some improvement with a big valve on the exhuast side when running a nice touch of Nos.
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dougmeyer
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posted April 30, 2007 03:04 PM
I could see (theoretically) looking for some better flow on the bottle, BUT- consider this,
if you are adding 50 or 100 hp (or more) with the nitrous, and you can change that at will with a simple jet change, why would you go to the trouble of machining the head, porting, and buying the valves just to find a few hp somewhere in there?
The stainless wouldn't be a bad idea at all, though.
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entropy
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posted May 01, 2007 03:41 AM
Me too, been curious about this topic for some time
i am getting ready (in June) to do back to back tests on a big valve head vs stock sized valve head. (both w/ss KW valves)
Both heads have similar minor porting/boot-matching, and both recently had their seats race cut on Metric MC's new "whammer-jammer" (osti TM) head machine.
Both will be set up w/60-65# seat pressure, and i'll use the same Muzzy cams at 107/110.
The dyno is a Factory Pro so no worries about DynoJet "different day, different results" syndrome.
i ought to start a contest to see who guesses the outcome most closely 
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TRNorBRN6001
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posted May 01, 2007 06:20 AM
Sounds like a neat project! After you keep the constants and have the results, you may want to play with the cam timing on the big valve head to find the best results. Maybe with the lower velocity it might be good to have late intake and early exhaust opening............ I may be completely wrong in my thinking though. Karl, the Garage Barbies want a Factory Pro at your house so you will spend more time with them!
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dougmeyer
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posted May 01, 2007 07:09 AM
OK, but NO other changes along with the head swap, OK? Same C/R right?
If you change the cam timing to "take advantage" of the big valves, you have to go back to the stock valve head and run the timing on THAT head to eliminate that as the reason for whatever change you see, right? Right. 
D.
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entropy
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posted May 01, 2007 07:26 AM
quote:
... you may want to play with the cam timing on the big valve head to find the best results...
Gary,
We think alike as usual.
The reason I am waiting till June to do this experiment is because Noonan is making me a new set of custom JE's with deeper pockets but a built up dome (keeps my CR hi).
The deeper pockets will allow fooling with cam timing bc now i can't really go much under 107 on intake without making the VTP too skinny.
big head? little head? lets see, eh?
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entropy
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posted May 01, 2007 07:26 AM
supra
sorry about the thread jack... 
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entropy
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posted May 01, 2007 07:38 AM
 Edited By: entropy on 1 May 2007 08:40
quote:
OK, but NO other changes along with the head swap, OK? Same C/R right?
If you change the cam timing to "take advantage" of the big valves, you have to go back to the stock valve head and run the timing on THAT head to eliminate that as the reason for whatever change you see, right? Right.
D.
Doug,
yep! exactly.
I don't understand all the tech mumbo jumbo you and the other experts offer me (you KNOW who you are ), but I do try to follow expert advice
I will assemble the new motor with the new deep pocket pistons, and small valve head, cams at 107/110.
Then mount the big head, cams at 107/110. See who wins round 1.
Then start playing with CL's on the large head; depending on results, go back to the small head, etc.
I am very open to any suggestions, just please don't suggest adding my other 2 sets of cams into this experiment (yet )
or maybe i'll start with the big head...
THEn go to the lil head...
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supra5677
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posted May 01, 2007 09:17 AM
I think there is something to be had with the exhaust valves...
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TRNorBRN6001
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posted May 01, 2007 11:21 AM
Get a hold of BossMan if you can he ran big valves on his exhaust side and had a SBM 1320 (paper thin) block if I remember correctly. I know he has had it Dynoed (at least a couple of times at JC's old place). I can not remember what kind of numbers he was running, but just N/A I do not think it was very impressive as he was mainly Built for Nos. I think he ran 120 shot and maybe a 150 shot. I do not know how that head gasket stayed for as long as it did!!!!
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NOS1290
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posted May 01, 2007 12:31 PM
I ran an intake cam on the exhaust side and a 1mm oversize exhaust valve setup 2 years ago, and saw a 7hp gain on a 1290 turning 12,400 rpm. BUT I would not attribute the gains to the exhaust valve change. I am still using OS exhaust valves from Orient. I still run a very large land on a 3 angle valve job to optimize thermal transfer for large NOS shots. The purpose of the larger SS valve with big lands and larger exhaust cam (advanced a bit) was to keep from melting valve heads off under spray. It was not my intention to make gains on motor, but I did see an improvement (due to several small changes). The valve job actually costs power. Since gave up on the inake on exhaust trick and run big Megacycle cams.
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supra5677
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posted May 01, 2007 01:08 PM
I saw your old post that said 9 horsepower... but your posting was the one I was referring too..
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dougmeyer
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posted May 01, 2007 02:46 PM
Now we're getting somewhere!
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supra5677
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posted May 01, 2007 04:15 PM
my buddies zx11 made 140 RWHP at 11,500 still climbing.. muzzy pipe and jet kit thats it..
My bike makes power to 10,750 then table tops to 12,200..
I HATE THAT..
zx11 has 31.5mm intake valves and 26mm on the exhaust.. As kawi says" the bore determines the valve size, the valve size determines the cam profile".. Not sure they followed this secret formula.. Reading from the Silver Book.. Have yet to see any 12 anywhere stock or kitted out, use the ENTIRITY OF THE POWER BAND... when I finally get the bike to do this I'll be happy similar to a 2004 Ninja 6RR..
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dougmeyer
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posted May 02, 2007 12:09 PM
Talk about a big apple and orange.
What makes you think "the entirety of the powerband" is not in use. Whose powerband, the one Kawasai designed or the one you have in your head?
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