Porting 101

[go-blow-or roll]

well first off the intake polishing thing is somewhat of a on going battel(polish-don't polish) think of it this way. no matter what you do you are still going to have a "drag" on the intake surface. the fuel is going to cover the intake runner, once this happens there is going to be to be some what of a surface resistance to the air-fuel mixture. when you polish the intake you are delaying the atomization of the fuel. so it must take place later on, which would be in the combustion chamber, this will cause a less eficient burn of the air fuel mixture. and when the fuel doesn't burn totaly the flame front propagation will not be even in the combustion chamber. i am not claming to be an expert by any means but i have been to school(still didn't learn to spell though lol) and i learned about porting from a man who has 20years expeariance. and also has many grass drag titels under his belt, not to mention the fastest 700cc(215hp) snomobile in the country.

[370banshee]

ok i'm jumpin in here. i was really trying not to. this is looking to be a E2S civil war or something. ok i'm not the porting expert or anything but i do know one thing. my ported 370 cyls are not polished. the polishe don't polish argument has banne and will continue to be an argument till the end of time. i've heard this same arugment dealing with chevy V8's. here what i ahve gathered in my travels so far. i've leanred that in something with valves the polishing seems to help on the intake side. but in a V8 you have alot of intake tract to atomise fuel. now to the part that you peopl wanna hear. in a 2 stroke it seems that the unpolished port seems to work good. i think "go-blow" is right about the rough surface aiding in atomosation of air fuel mix. (sorry steve i usually agree with you) but heres the real deal i say just pay somebody to port it. whatever they do just live with that. and i really think that youi probably won't tell the difference between polished or not. being taht your just a rec. rider not a big time drag racer or MX rider. hell they may not even be able to tell the difference. if i were you i'd definatly pay somebody to do it. talk to scott at SORE he can probably get ti done for you or point you in teh right direction for a very good shop that does a LT500 port. other than that just take it out and ride it. oh yeah and don't pull up and talk smack next to the wrong shee!!! lol

[Bandit]

mcdizzy has a big long artical on his website about this somewhere i will try to find it

[370banshee]

solo you look on macdizzy.com also?? i thought i was the only one.

[Bandit]

yea i sure do, theres some very good info on that site, i've learned alot by reading up on there

[atcsteve]

yea I was not sure I was going off what I have and what I was told,Im defenatly not an expert.I was hoping to learn, not to start a war! hope I didnt come across that way.anyway everybody has their opnions and thats what makes racing fun. P.S. my shee needs a litle help didnt do to well sat. night.

[370banshee]

little help huh?? how bout some 404 sleeves, drag porting, and a 4mm stroker. would that help!!! if you build that lemme know how it runs. thats kinda what i'd like to build for my 96 shee.

[ReeperLT500]

Well I ported my LT250 and didn't really hog out the ports just opened them up alittle and polished them(intake and exhaust). The bike never used to rev but now the thing pulls hard at high rpm. The bike feels like a completely different quad.

Now on my zilla ofcourse it's not gonna rev like my 250 that I know. But I would like it to get a few more rpms. It seems to kinda fall on it's face after midrange. The FMF pipe that's on it just says "gold series" don't know if it's a high end or low end pipe. I thought all gold series were high rpm pipes? I have heard of the term atomization which like 370shee said about v8's(will mix later). I've ported my on intake on my car, 250 and yes my push lawnmower. (practicing) I just can't justify paying someone when I can do it. So from all the replies/opinions I think I'll try it different on the zilla.

Port the intake
Port and polish the exhaust

Thanks gentlemen for all the advice. -Mark

[go-blow-or roll]

something else i wanted to add, and not get back into the polish and don't polish thing. but porting on the banshee is some what of an chore and they are a little diffacult and take alot of time to get them "right". most of the 'shee motors i have see the ports were pretty far off (from the deck to the top of the ports) this is the reason i had to go with the (full race) port&polish. while not all are as far off as mine were, i had to find other ways to get more bottom and mid-range power. i.e. reeds,pipes...... may be i'm just babling but just something to think about before getting a port job done.