Custom head porting

[joeb2300]

Has anyone ever tried to port their own head? I found a cylinder head for really cheap and thought about taking a dremel to it and then wet sand it. Then polish it with wax powder to give it a real "polish"

It just seems like every port job I've seen doesn't really look polished but rather scratched on. I mean why pay $500+ for a port and polish if it isn't even polished?

[joeb2300]

Heres what Im talking about. This is ported but definitely not polished.

[Fred55]

Polishing to a shine will actually hurt power. You want the surface to be rough. Similar to the way a turbulent air layer around a golf ball, caused by the dimples, helps it travel farther.

See page 5 under port polishing
http://www.stealth316.com/misc/grapeape-inductionsystems.pdf

[Fred55]

The rough surface also helps mix the fuel into the incoming air.

[eastside 400]

you want a rougher intake port but a smooth and polished exhaust port and combustion chamber. All the polishing does is help keep the carbon from combustion from sticking to the port walls and building up

[01boneless]

u could prolley polish it your self just dont do the intake... here how my exhaust port looks

[njquadracer11]

^^^^^ noooooo you wanna do the opposite, you never everrr want to touch the exhaust, the intake is what you need to open up

[eastside 400]

thats not true. and he also said polish, not port. But making the intake bigger isnt always better. It depends on what year bike you have, cam selection, where you want your power. There is way more to porting a head then just taking a dremel and hogging it out. Unshrouding the valves will pick up big gains, working the valve guides is huge too. On 04-05 heads you need to actually make the intake port smaller by applying epoxy to the roof of the port.

[01boneless]

Originally posted by njquadracer11
^^^^^ noooooo you wanna do the opposite, you never everrr want to touch the exhaust, the intake is what you need to open up

no offence but your completly wrong... u NEVER polish a intake port, u can open up intake and exhaust but only polish exhaust ports intake must stay rough

[njquadracer11]

no offence but your completely wrong...ask any somewhat knowledgable engine builder and they will tell you that the reason you cut the intake port up and make it rough is for a better air/fuel mix and better fuel atomization....they will also tell you that you done want to touch the exhaust port that much because when you open up the exhaust port you have less back pressure which in turn means less tourque

[njquadracer11]

no offence but your completely wrong...ask any somewhat knowledgable engine builder and they will tell you that the reason you cut the intake port up and make it rough is for a better air/fuel mix and better fuel atomization....they will also tell you that you done want to touch the exhaust port that much because when you open up the exhaust port you have less back pressure which in turn means less tourque

[TheAwesomehonda]

You want the intake rough to mix the fuel and air.. The exhaust smooth to let it flow better..

[mx Eli]

Originally posted by njquadracer11
no offence but your completely wrong...ask any somewhat knowledgable engine builder and they will tell you that the reason you cut the intake port up and make it rough is for a better air/fuel mix and better fuel atomization....they will also tell you that you done want to touch the exhaust port that much because when you open up the exhaust port you have less back pressure which in turn means less tourque


if this is true tell me why every major engine build that i know of in the atv industry port the exhuast side too

[01boneless]

Originally posted by njquadracer11
no offence but your completely wrong...ask any somewhat knowledgable engine builder and they will tell you that the reason you cut the intake port up and make it rough is for a better air/fuel mix and better fuel atomization....they will also tell you that you done want to touch the exhaust port that much because when you open up the exhaust port you have less back pressure which in turn means less tourque

these knowledable builders dont build much do they?

[05 450R in pa]

you only port the intake,you port AND polish exhaust..you only port intake because a lil roughness is needed to give the incoming air turbulance and help with mixing of fuel...you port and polish exhaust to allow the exhaust to exit quicker,you can only bring in as much air as you can push out (been told this numerous times by multiple builders)...and on the less back pressure equals less torque its total B.S. and untrue,if that was true then how do you actually gain torque when you run an aftermarket exhaust??

[01boneless]

Originally posted by 05 450R in pa
you only port the intake,you port AND polish exhaust..you only port intake because a lil roughness is needed to give the incoming air turbulance and help with mixing of fuel...you port and polish exhaust to allow the exhaust to exit quicker,you can only bring in as much air as you can push out (been told this numerous times by multiple builders)...and on the less back pressure equals less torque its total B.S. and untrue,if that was true then how do you actually gain torque when you run an aftermarket exhaust??
very well put .. he know whats up!