porting specs

[bansh450]

hey there every one I'm new to this. I'm moving from 450's to banshees my daughter has a banshee and now i have one. i used to have a yfz 450 before i blew it up, since then Ive taken all the good 450 parts and put what i could on my banshee, 450 front end that widened me almost 6" in the front all custom paint and i did it all. i love my quad and it came to me in a box and I'm having fun making it mine.

i have a 4mm crank, 35mm carbs, stock cylinders, stock head all brand new.

 

 

 

 

i wont to port and polish full race port polish. my lower end has already been done now i need some feed back on spects maybe pictures or someone to talk to that isn't trying yo make money because this is something i will do my self. so if any one has info please send it my way.

[sinisterboo]

you are stepping into a mine field asking that question. seriously involved job that take skill, patience, and most of all, experience! I'm not saying you are incompetent, or un-skilled, just saying its cheaper in the long run to get someone to do it. Or buy a cub, LOL

[rb0804]

you are stepping into a mine field asking that question. seriously involved job that take skill, patience, and most of all, experience! I'm not saying you are incompetent, or un-skilled, just saying its cheaper in the long run to get someone to do it. Or buy a cub, LOL

 

 

i agree there is so much to the stock banshee cylinders, they are so f'd up

[Titan up]

We'd like to see your Banshee,post up some pics!!

[bansh450]

you are stepping into a mine field asking that question. seriously involved job that take skill, patience, and most of all, experience! I'm not saying you are incompetent, or un-skilled, just saying its cheaper in the long run to get someone to do it. Or buy a cub, LOL

[bansh450]

you are stepping into a mine field asking that question. seriously involved job that take skill, patience, and most of all, experience! I'm not saying you are incompetent, or un-skilled, just saying its cheaper in the long run to get someone to do it. Or buy a cub, LOL

 

 

i ported my stock stroke banshee already and it runs grate its only for my 16 year old daughter so i didn't go to radical. and I've been told you cant use a stock port on a 4mm i have all the tools and i have a good know how. i just don't know about the 4mm. im looking for the numbers. thanks

[bansh450]

We'd like to see your Banshee,post up some pics!!

as soon as i figure out how. the yfz 450 front end fit good i only had to move one mount on the lower a arm and 1/8th " over on the shock mount

[sinisterboo]

Well, with a 4mm stroker crank, you are basically pushing the piston up 2mm higher out the top, and pulling it 2mm further down the hole. But the stroker also affects piston speed, and the duration at which the piston stays at the top and bottom. what pistons are you using? standard? or 795 series? plate under the cylinders or cut domes? For me, when I build a 4mil motor, I dont use the plate, and just port accordingly, and run domes that are cut to clear a 795 series piston and I use longrods.

[bansh450]

Well, with a 4mm stroker crank, you are basically pushing the piston up 2mm higher out the top, and pulling it 2mm further down the hole. But the stroker also affects piston speed, and the duration at which the piston stays at the top and bottom. what pistons are you using? standard? or 795 series? plate under the cylinders or cut domes? For me, when I build a 4mil motor, I dont use the plate, and just port accordingly, and run domes that are cut to clear a 795 series piston and I use longrods.

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its not the long rod and the pistons are standard. I'm not sure if i should use the plate or not?? i have a cool head by pro design that came with the quad the old owner said he had nothing but problems with it so i wasn't going to use it.

i was thinking if i did use the plate it would make things easier. but every one i talk to says the porting i have now wont work on a 4mm. i have a stock set of cylinder that ill report that's no problem. so do i port 2mm down and 2mm farther up with no plate? and with a plate everything has to go down right? that's the reason a race port wont work on a 4mm you want to move the exhaust down and a race is up and down that's why the exhaust has to have at least 28mm to the top?

well any info you can pass on will help

[Wildcardracing]

Running no plate, you will move the exhaust and transfer port floors down 2mm, how much you raise each of them will depend on what kind of port you are trying for, pipes and rider wieght. You can just use a plate and bolt it together, but it won't run as well and the floors of the ports won't be flush with the piston at bdc. I recommend not using the plate because it is just one more sealing surface to develope an air leak. I've personally never had any issues with my cool head, and cut domes are by far the best way to go on a stroker IMO. What kind of riding do you do with your banshee? What pipes are you running? These are two ?'s you will need to answer before you cut anything.

[bansh450]

Running no plate, you will move the exhaust and transfer port floors down 2mm, how much you raise each of them will depend on what kind of port you are trying for, pipes and rider wieght. You can just use a plate and bolt it together, but it won't run as well and the floors of the ports won't be flush with the piston at bdc. I recommend not using the plate because it is just one more sealing surface to develope an air leak. I've personally never had any issues with my cool head, and cut domes are by far the best way to go on a stroker IMO. What kind of riding do you do with your banshee? What pipes are you running? These are two ?'s you will need to answer before you cut anything.

 

cpi in frame pipes, all out riding all the time. mostly weekend hill climing and some trail riding all on soft oregon sand.my budy has a stock stroke banshee with a full drag port and cpi pipes he says he is running at about 75 hp i want more than that.

[Wildcardracing]

Well, looks like your wanting an aggressive dune port to be honest. CPI's live real nice around 196 deg of exhaust duration. Given a -2mm deckheight(no plate with stroker domes)that would put you at @26.78mm from the deck to the port roof. On the transfer ports you should cut them between 127 and 130 deg to have proper timing, depending on rider weight. The more transfer duration, the smoother the power delivery but a little less overall power at peak. So 127deg =43.05mm, 128 deg=42.85mm, 129deg=42.64mm and 130deg=42.44mm. All of those measurements are from the deck of the cylinder to port roof based on a -2mm deck. Add 2mm to the measurement if running a plate. Hope that helps. Good luck. As a note, I take absolutely no responsibility if it doesn't turn out right. But, I won't discourage anybody from porting thier own engine. Every builder had a first port job and most have learned the hard way through trial and error.

[bansh450]

Well, looks like your wanting an aggressive dune port to be honest. CPI's live real nice around 196 deg of exhaust duration. Given a -2mm deckheight(no plate with stroker domes)that would put you at @26.78mm from the deck to the port roof. On the transfer ports you should cut them between 127 and 130 deg to have proper timing, depending on rider weight. The more transfer duration, the smoother the power delivery but a little less overall power at peak. So 127deg =43.05mm, 128 deg=42.85mm, 129deg=42.64mm and 130deg=42.44mm. All of those measurements are from the deck of the cylinder to port roof based on a -2mm deck. Add 2mm to the measurement if running a plate. Hope that helps. Good luck. As a note, I take absolutely no responsibility if it doesn't turn out right. But, I won't discourage anybody from porting thier own engine. Every builder had a first port job and most have learned the hard way through trial and error.

great thank you so much.

[bansh450]

Well, looks like your wanting an aggressive dune port to be honest. CPI's live real nice around 196 deg of exhaust duration. Given a -2mm deckheight(no plate with stroker domes)that would put you at @26.78mm from the deck to the port roof. On the transfer ports you should cut them between 127 and 130 deg to have proper timing, depending on rider weight. The more transfer duration, the smoother the power delivery but a little less overall power at peak. So 127deg =43.05mm, 128 deg=42.85mm, 129deg=42.64mm and 130deg=42.44mm. All of those measurements are from the deck of the cylinder to port roof based on a -2mm deck. Add 2mm to the measurement if running a plate. Hope that helps. Good luck. As a note, I take absolutely no responsibility if it doesn't turn out right. But, I won't discourage anybody from porting thier own engine. Every builder had a first port job and most have learned the hard way through trial and error.

one more thing on my other set of cylinders the intake is hogged out almost 6mm higher than stock with 3.5mm holes drilled on the sides will that be the same on my cylinders?

[Wildcardracing]

one more thing on my other set of cylinders the intake is hogged out almost 6mm higher than stock with 3.5mm holes drilled on the sides will that be the same on my cylinders?

Personally on my port jobs, I do a full reshape of the intakes...but, enlarge them only enough to clean up the casting flaws. I try to enhance flow characteristics as much as possible without slowing down intake velocity. This is one area where a lot of builders disagree. Ask any five builders what intake size/shape/texture works the best and you'll likely get five different answers. I have experimented a lot with auxillery ports and found that they actually slow my engines down some. There are builders who swear by them, but I haven't found them to give any advantage in my portwork. I know what works best for me, but what works best for someone else may be different.