my First home 4mil porting

[Larry's Shee]

Looks real good so far 9090. Is this a clean up port job or did you raise / widen any of the ports? Be sure to champher the exhaust and transfer ports so the rings don't snag. Tried sending you a PM yesturday and it wouldn't go thru. Be sure to post pics before you bolt it back together , and let us know how it runs when your done !! Pasi , that's a good shot, beautiful job !!

[banshee9090]

Looks real good so far 9090. Is this a clean up port job or did you raise / widen any of the ports? Be sure to champher the exhaust and transfer ports so the rings don't snag. Tried sending you a PM yesturday and it wouldn't go thru. Be sure to post pics before you bolt it back together , and let us know how it runs when your done !! Pasi , that's a good shot, beautiful job !!

 

ya pal i will do that , actually i m looking for the maximum hp can 4mil give so i m doing 4mil porting that means i cut 2mm from the bottom of the transfair port except the one above the intak and the bottom of exhaust port , i will not tuoch the top of the ports and will widen all ports as i can.

[AKheathen]

uh-oh buddy....you need to at least get those port heights to proper, or at least close durrations, measured in degrees of rotation. masically, get a timing wheel, find an accurate top dead center, and measure when they open, and for how many degrees, then correct them. now, as a short-cut, you can probably take close to 1.5-2mm from the top of the exhaust, and be kind of close to corrected on timing, but it will be a more mid-range oriented motor. i'm guessing you are more of a duner? what pipes are you running? 2 stroke porting is verry different than 4 stroke. they really don't need to be, or benifit from being hogged out. you can actually loose a lot of power, because the airspeed slows down. before you touch the transfers on the 2nd set, get your plan and measurements worked out. "plan your work, and work your plan" we are here to help you out.

[banshee9090]

uh-oh buddy....you need to at least get those port heights to proper, or at least close durrations, measured in degrees of rotation. masically, get a timing wheel, find an accurate top dead center, and measure when they open, and for how many degrees, then correct them. now, as a short-cut, you can probably take close to 1.5-2mm from the top of the exhaust, and be kind of close to corrected on timing, but it will be a more mid-range oriented motor. i'm guessing you are more of a duner? what pipes are you running? 2 stroke porting is verry different than 4 stroke. they really don't need to be, or benifit from being hogged out. you can actually loose a lot of power, because the airspeed slows down. before you touch the transfers on the 2nd set, get your plan and measurements worked out. "plan your work, and work your plan" we are here to help you out.

 

AKheathen thank you for your kind , my i ask you ,what do you mean by take close to 1.5-2mm from the top of the exhaust, and you are correct i m more of a duner , I run t6 but I can run stage III do you think stage III pipe is ok for setup

 

All I m doing is to align the top of the pistons to the bottom of the transfer port and also will do the same with exhaust port,most of the guys doing this when they go form stuck crankshaft to 4mil crankshaft they call it 4mil porting. i did not get your point why it will be more mid-range orinted motor, is that means my setup will not give me the full power for 4mil when it use to be if so why pleas!!.

Edited October 10, 2010 by banshee9090

[AKheathen]

first thing- the tr-6 pipes are made for a stock motor. they will definitely choke out the 4mill. i forgot to ask, and assumed that you are using recessed domes, or head, or at least a head spacer. are you using the spacer plate under the cylinders? that will make it back to more top-end power range, but not leave enough material in the transfers for a decent mid-range power. best thing you can do is ditch the plate if you have it, and measure the degrees of when each port opens using the degree wheel. in worse case scenario, where you are just guessing, simply opening the top of the exhaust (like you are doing with the bottom of the exhaust port) by 1.5mm-2mm will get you kind of close to a decent running port time. if you can map it out- you want the exhaust to be open for about 186-188 degrees of rotation, and the transfers 30-31 degrees after that, for a total open time of 128-124 degrees. try to keep them resembling the same over-all shaping as stock, but angling the air a little more upward and toward the carbs. keep the center transfer that paints at the reeds at a steep angle, and widen it some. i could not come up with any info on the "stage 3" pipes you are talking about, but i hae seen some European pipes made resembling older fmf pipes that have a more mid to mid-top power profile, which is dune friendly, but will also make a big difference in how you should be ported. so, i need as much information on the pipes as you can give, and what method you are using for the stroker clearance (plate, domes, etc)

[banshee9090]

first thing- the tr-6 pipes are made for a stock motor. they will definitely choke out the 4mill. i forgot to ask, and assumed that you are using recessed domes, or head, or at least a head spacer. are you using the spacer plate under the cylinders? that will make it back to more top-end power range, but not leave enough material in the transfers for a decent mid-range power. best thing you can do is ditch the plate if you have it, and measure the degrees of when each port opens using the degree wheel. in worse case scenario, where you are just guessing, simply opening the top of the exhaust (like you are doing with the bottom of the exhaust port) by 1.5mm-2mm will get you kind of close to a decent running port time. if you can map it out- you want the exhaust to be open for about 186-188 degrees of rotation, and the transfers 30-31 degrees after that, for a total open time of 128-124 degrees. try to keep them resembling the same over-all shaping as stock, but angling the air a little more upward and toward the carbs. keep the center transfer that paints at the reeds at a steep angle, and widen it some. i could not come up with any info on the "stage 3" pipes you are talking about, but i hae seen some European pipes made resembling older fmf pipes that have a more mid to mid-top power profile, which is dune friendly, but will also make a big difference in how you should be ported. so, i need as much information on the pipes as you can give, and what method you are using for the stroker clearance (plate, domes, etc)

 

Ok , No spacer plate under or above cylinder, I run cut domes 2mm

 

Sorry I mean (stage IV) pipe it is made in America it is resembling t5, I will try to fix it because it has small accident between the connection of the pipes , and let you know the output.

[AKheathen]

Ok , No spacer plate under or above cylinder, I run cut domes 2mm

 

Sorry I mean (stage IV) pipe it is made in America it is resembling t5, I will try to fix it because it has small accident between the connection of the pipes , and let you know the output.

okay.....those trinity pipes will be pretty decent for dune setup.... start off with 186 degrees exhaust, keeping nice, curved edge to the shape of the opening, and widen it to 65% of bore diameter. set the transfers to 124 degrees open. chamfer all edges to prevent ring snag, and break it in on these timings. you can cut more out to increase durations after-wards, without needing to re-bore/hone, as ling as you don't ding them up again. if you find that the power seems to be too low in the rpm range, you can increase the exhaust duration, but keep the blow-down no more than 32 degrees. ideally, between 29.5 and 32 degrees blow-down is a good range to work with. if it seems a bit too peaky, and fall "off the pipe" too sharply, you can smooth it by decreasing blow-down when you increase transfer duration.

[banshee9090]

okay.....those trinity pipes will be pretty decent for dune setup.... start off with 186 degrees exhaust, keeping nice, curved edge to the shape of the opening, and widen it to 65% of bore diameter. set the transfers to 124 degrees open. chamfer all edges to prevent ring snag, and break it in on these timings. you can cut more out to increase durations after-wards, without needing to re-bore/hone, as ling as you don't ding them up again. if you find that the power seems to be too low in the rpm range, you can increase the exhaust duration, but keep the blow-down no more than 32 degrees. ideally, between 29.5 and 32 degrees blow-down is a good range to work with. if it seems a bit too peaky, and fall "off the pipe" too sharply, you can smooth it by decreasing blow-down when you increase transfer duration.

 

Yes thanks , I will Exercise degree wheel I will see if I can got your pint well !

 

 

[banshee9090]

I measured degrees of rotation , I got a timing wheel copy from internet I start from TDC , when timing wheel zero , the exhaust port open around 90 degrees and the transfers port open 60-75 degrees , I what do you think about this output pleas

[AKheathen]

I measured degrees of rotation , I got a timing wheel copy from internet I start from TDC , when timing wheel zero , the exhaust port open around 90 degrees and the transfers port open 60-75 degrees , I what do you think about this output pleas

you need more exact measurements. and it helps to do the full degrees from when it opens, to when it closes. for example- 188 degrees rotation open exhaust. 127 degrees open transfers. that would give you a blow-down of 30.5 degrees.

or, are you saying that the transfers open at 75 degrees, and the piston lines up with the bottom of the transfer ports ate 60 degrees? the full open rotation in degrees is also more precise, in case you have the tdc off a bit, or a half-degree, like my example....

if that is true about your measurements, you still only have 180 degrees exhaust, and 15 degrees blow-down. that will give you a lower rpm motor, that has no real power-band. i do not think those measurements are accurate, though. stock, it should come up with like 178 and 124? don't remember what it usually comes out to, but i'm sure it was a bit more than 15 blow-down, more like 26. the best way i was told to do it was to use a chunk of square stock bolted to the top of the cylinders as a piston stop, then you can measure the degrees it travles, and match it up with the wheel.

[banshee9090]

you need more exact measurements. and it helps to do the full degrees from when it opens, to when it closes. for example- 188 degrees rotation open exhaust. 127 degrees open transfers. that would give you a blow-down of 30.5 degrees.

or, are you saying that the transfers open at 75 degrees, and the piston lines up with the bottom of the transfer ports ate 60 degrees? the full open rotation in degrees is also more precise, in case you have the tdc off a bit, or a half-degree, like my example....

if that is true about your measurements, you still only have 180 degrees exhaust, and 15 degrees blow-down. that will give you a lower rpm motor, that has no real power-band. i do not think those measurements are accurate, though. stock, it should come up with like 178 and 124? don't remember what it usually comes out to, but i'm sure it was a bit more than 15 blow-down, more like 26. the best way i was told to do it was to use a chunk of square stock bolted to the top of the cylinders as a piston stop, then you can measure the degrees it travles, and match it up with the wheel.

 

Let say If I start at piston TDC rotating the crankshaft full one turn will read 180 degree that is full revolution of the crankshaft 180 degree, what do you mean by 188 degree ? i m saying the transfer port open at 75 degree and the piston line up with top of the transfer port!

the exhaust open at 90 degree and the piston line up with the top of the exhaust port that is my measurment !

Edited October 17, 2010 by banshee9090

[banshee9090]

Let say If I start at piston TDC rotating the crankshaft full one turn will read 360 degree that is full revolution of the crankshaft 360 degree, what do you mean by 188 degree ? i m saying the transfer port open at 75 degree and the piston line up with top of the transfer port!

the exhaust open at 90 degree and the piston line up with the top of the exhaust port that is my measurment !

sorry i just correct above 360 degree full turn of the cranckshaft so from tdc to bdc is 180 degree wht do u mean by 188 degree pleas ?

Edited October 17, 2010 by banshee9090

[AKheathen]

sorry i just correct above 360 degree full turn of the cranckshaft so from tdc to bdc is 180 degree wht do u mean by 188 degree pleas ?

the timings are measured based on full 360 degree rotation. so, the top of the piston lines up with the top of the port as it rotates and that is where you start counting degrees as it keeps rotating untill it lines up again on the upwards stroke and closes. the only measurement not measured in the full 360 is "blow-down" that is the degrees from when the exhaust opens, to when the transfers open. you can get more precise, like .5 degree increments, by subtracting the transfer time from the exhaust time and dividing by 2

[banshee9090]

the timings are measured based on full 360 degree rotation. so, the top of the piston lines up with the top of the port as it rotates and that is where you start counting degrees as it keeps rotating untill it lines up again on the upwards stroke and closes. the only measurement not measured in the full 360 is "blow-down" that is the degrees from when the exhaust opens, to when the transfers open. you can get more precise, like .5 degree increments, by subtracting the transfer time from the exhaust time and dividing by 2

 

I would say Thank you for correct my earlier measurement, I will Keep in touch. I would ask how helpful rewindow the pistons intake port to match with cylinder intake port?

 

Edited October 18, 2010 by banshee9090

[AKheathen]

I would say Thank you for correct my earlier measurement, I will Keep in touch. I would ask how helpful rewindow the pistons intake port to match with cylinder intake port?

 

i would not touch them. it weakens normal pistons. you can buy some that are already manufactured with the bigger windows, and boost porting. on those, they are beefed up when they make them.