Porting 101

[ReeperLT500]

What is the bottleneck about the zilla motor? I have a 90 and what would be ideal for porting? Does the intake port need to be bigger or exhaust port or both for that matter? I wanna try and get a few more rpms out of it. Thanks.

[bansheeracer18]

the intake ports are grinded out for more flow and if you polish them you get even better flow for the exaust port leave it and get a good aftermarket pipe if you want more rpm's

[87quadzilla_guy]

yeah if iwas you i would just port the intake ports and have it polished and worry bout getting a pip that will make it run a hole lot better ang give ya extra rpm's

[ReeperLT500]

It has a FMF pipe and exhaust with pro series reeds. But I just wanted it to rev up alittle more. So port the intake and just smooth out the exhaust? -Mark

[atcsteve]

yes do intake and polish.power pro's makes a good drag pipe for it.you'll feel that for sure! I think they are about $270 my cost.also I have a rare K.R. drag pipe used,like the one on my 250r atc pictured here.Its going for $375,not a better pipe out there!

[go-blow-or roll]

bout to make some enamies here!! ok first of all do not polish your intake ports!!!! clean them up thats all. the roughness of the port helps to atomize your in comming fuel. along with the turbulance it causes.you want the air comming into the carb to be as smooth as possible after that you need turbulance, to mix the air fuel mixture.if your going to polish anything do the exhaust port!! it will help with carbon build up. as for the porting it self if you change your exhaust or intake ports your going to move your power band.so it depends where you want it to "hit" i moved my exhaust port down about .050 on my snowmobile and it has a great mid-range.and keeps pulling. another thing you want to check is that the ports are the same distance from the deck. well nuff blabing if you need more help be glad to help.

[atcsteve]

its all good,but I was wondering if the advise about not polishing the intake ports was from yamaha?and you are right about where you port and where it hits,but Ive found that when you polish the intakes its a smoother and faster flow.is this not correct?and yes polishing the exaust ports is a must!Im just getting ready to new my "new" shee 89 but I just want to ride the hell out of it since I got her.Im also lookin for a good price on a 5-6mmrod kit,if anyone know somewhere with good prices please let me know.thanks

[zillaguy89]

Are you looking for the engine to physically rev farther, or are you just looking to move the powerband up. if you just want the powerband to move up, you'd have a lot less work involved in just doing a pipe change. You say you have an FMF pipe on it. is it a "Gnarly" style, for low end powerband, or is it, say, an "SST" pipe for screaming it up high? I think those may be banshee pipes, but the concept is still the same. I think there was a good post on here somewhere that explained what porting in specific areas did, but I may be mistaken.

[atcsteve]

yea there is a lot to do with porting,including that you have to factor in what exaust,your top end fuel intake and what your after.Ive done my own 250r's and just hogged the crap out of em and also just clean up existing ports.you figure out where you want the power and then go to fuel&air intake then exaust,then gearing it all plays a big part.Ive seen guys who have good port jobs and the wrong air&fuel or exaust and lose power.i broke down ans sent my good 250r out toESR racing for a stage 2 port,then I figured out the rest and what a rocket! I would recommend them to anyone,they do great work

[zillaguy89]

yeah....porting is definitely something you want to leave to a professional. Unless you have experience in this field, which I personally don't. hell, my 2-stoke won't even run right, its 30 years old, it needs a top end for starters. BUt be it 2 stroke or 4, it needs the same things to run properly. a 2 stroke just does it in half the time. =) so honestly, again, you gotta know twice as much about what your doing if you don't wanna get screwed. Every little thing you do makes twice the impact.