99midnightZ

my buddy has a zx12....and he is wanting to port and polish the head but was just currious what hp gains he could get and if its worth it...so ne one who has done it...i need your opinion...thanks

Mike_C.

I dont know about the ZX12 but in general, yes porting and polishing the head is one of the oldest and best ways to get natural hp's out of an engine. Not many people do it now beacause tech. has gone past pulling the engine apart and just plug in a PC3 or other componants for fi bikes. Plus its big bucks to pay someone to do it who knows what they are doing. Lots of manuel labor. Its not something you want to try and find a good deal on even though Jose says that he can do it for 200 bucks in his shead in the back yard you dig?

Thats all I have to say about that

ZXLNT

Unless your doing other engine work with it like a big bore kit or stroker, I wouldn't mess with it..

zx racer

u can make more HP out of your heads by porting and polishing, cams will wake a motor up, but if your not going to race the bike and just only street ride it, then i would say it's a waste of money to me, spend that money somewhere else on the bike besides the head

Motowerkz

Porting your head??? Bigger is not always better. Porting might help to increase CFM but will reduce your intake velocity. Look at this picture from www.mototuneusa.com on how from the factory is increasing horsepower using the secrets from MotoGP and the AMA bikes(there making the intake ports smaller)...Left to Right-Stock, Race, 07' Race

hiyaboa

HAHAHAHA Not that website again....lol. I cant believe anyone actually believes that shit.

mr.croom

Polishing is always the way to go if you are uncertain about WHAT PARTS OF THE HEAD need to be ported. Smoothing the flow tract of the intake and exhaust is where the power is at. Lots of heads come polished from the factory nowadays.

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Phantom13

You NEVER polish the intake side of the head.


Everything 9er said is 100% the truth.



The Stock ZX-12R CAN use a light "clean-up" in the ports along with some reshaping here and there.... but by no means does it need to be opened up unless you're increasing displacement. Either way, any kind of headwork is something you do on a racebike. If a little more power is what you're after, there's no better bang for the buck than a dry nitrous kit using a small and SAFE 20-30hp shot of nitrous. Just be sure to have the A/F and ignition timing properly set-up for it.

__________________
2003 Ace Performance Stage 2 R-Spec ZX-12R
ECTA #9577
205.6mph @ Maxton.... All Motor.

www.AcePeformanceRacing.com

mr.croom

Ok, I'll bite. Explain why you should NEVER polish the intake side of the cylinder head. I'm sure the Kawasaki factory would like to know as well, being that they started polishing intake ports from the factory, with the introduction of the 2005 ZX-6RR.

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Phantom13

A smooth surface, such as a polished one, creates puddling of fuel which leads to poor fuel atomization. Only the exhaust ports benefit from a polish.

You want fuel to break-up into the air for a more efficient burn, not drip down the ports.

The gains achieved via a more efficient fuel burn greatly outweight any miniscule increase in intake velocity achieved with polishing the intake ports. Polishing the intake is much like the saying, "Stepping over a dollar to pick up a dime."



btw, Kawasaki doesn't "polish" the intake ports, they hand finish them. There's a difference.

__________________
2003 Ace Performance Stage 2 R-Spec ZX-12R
ECTA #9577
205.6mph @ Maxton.... All Motor.

www.AcePeformanceRacing.com