how, what is the diff in port work?

[DEERCHOOPER]

ok i read this porting does this or works in this rpm range.


my question is, what is the actual differance in the port work?

can you look into your cylinder and compair it to another one and see what/ how its different?

if i were to just go into my cylinder and clean up all the casting marks and smooth it out, knife edge all dividers, what would it be?

all the years the 2 stroke porting has been around someone should know something, lol.

[rustyATV]

Yeah, a lot of people know something, but most guard it closely to make money off it.

You can tell a little between cylinders that are greatly different by looks (i.e. a woods cylinder vs a drag cylinder), but generally you're going to need to use a degree wheel and do a port map. The resulting port timing and area is where the nature of the cylinder is revealed.

Port map
http://www.macdizzy.com/cylinder_map.htm

Stock porting tends to be rather low ranged and mild on the 250R. I raced woods for a number of years with a cylinder that had cleaned up transfers and epoxied/raised .5 degree secondaries. With a PT Type 6 pipe, it was a tractor. Never tried it with my '03 race pipe, though.


P.S. Don't "Knife Edge" things. Smooth and blend to reduce losses.

[DEERCHOOPER]

thanks for the link, i like reading stuff like that.

i see what your saying and thank you.


would anybody like to add to this topic?


__________________

[1promodfan]

Originally posted by DEERCHOOPER
ok i read this porting does this or works in this rpm range.


my question is, what is the actual differance in the port work?

can you look into your cylinder and compair it to another one and see what/ how its different?

if i were to just go into my cylinder and clean up all the casting marks and smooth it out, knife edge all dividers, what would it be?

all the years the 2 stroke porting has been around someone should know something, lol.

Well, Rusty pretty much covered it. Can most people look at a cylinder and tell what kind of port work has been done??? I say probably not. Someone has to know something, yea, but they say it takes years to learn how to do it.

My stock cylinder had been ported when I got it, but I had no idea what type of port job it had. I know a drag port has been ported more, but I would have to see two cylinders side-by-side. I took it to C-Leigh Racing and he told me as soon as he seen it what kind of porting was done.

I would say the actual difference would be in the timing of the ports, which kinda determines where your power is made. But, I have to say that I have NO IDEA how to do any kind of porting. And my comments may be way off........if so anyone can feel free to correct me...LOL!!

[DEERCHOOPER]

cough cough C-Leigh Racing cough cough

[1promodfan]

Originally posted by DEERCHOOPER
cough cough C-Leigh Racing cough cough

^^^^What does that mean???.....hopefully something good!!

[DEERCHOOPER]

that means,

i hope c-leigh would chime in.

[regg187]

yes, where is neil?

[regg187]

Originally posted by DEERCHOOPER
ok i read this porting does this or works in this rpm range.


my question is, what is the actual differance in the port work?

can you look into your cylinder and compair it to another one and see what/ how its different?

if i were to just go into my cylinder and clean up all the casting marks and smooth it out, knife edge all dividers, what would it be?

all the years the 2 stroke porting has been around someone should know something, lol.

That is like a stage 1 port job, clean up the casting flaws, sharpen up the radius on the transfers, and raise the exhaust no more than 1 mm, but do not widen the exhaust. then you will have to bump up the compression a little, because of the raised exhaust, the compresiion stroke happens 'later' and doesn't last as long so compression drops and you need to get it back up to where it was before or higher if it is stock pressures. doing this you really aren't making any major port timing changes, just a bump in all over performance.

Now if you widen and raise transfers and exhaust you will be making major changes, doing 1 thing might help your lowend and another will only make topend HP that is where the skilled guys like C-leigh come in and do their magic to get you a powerband that you desire.

To look in and see a difference yes you can but normally it takes having a piston to move up and down to see when certain ports become uncovered, to see changes and a pair of calipers to check the width of ports to see if they have been widened or re shaped
but looking inside you will see smoothed up areas with shiny metal where it was ground and polished

[DEERCHOOPER]

Originally posted by regg187
That is like a stage 1 port job, clean up the casting flaws, sharpen up the radius on the transfers, and raise the exhaust no more than 1 mm, but do not widen the exhaust. then you will have to bump up the compression a little, because of the raised exhaust, the compresiion stroke happens 'later' and doesn't last as long so compression drops and you need to get it back up to where it was before or higher if it is stock pressures. doing this you really aren't making any major port timing changes, just a bump in all over performance.

Now if you widen and raise transfers and exhaust you will be making major changes, doing 1 thing might help your lowend and another will only make topend HP that is where the skilled guys like C-leigh come in and do their magic to get you a powerband that you desire.

To look in and see a difference yes you can but normally it takes having a piston to move up and down to see when certain ports become uncovered, to see changes and a pair of calipers to check the width of ports to see if they have been widened or re shaped
but looking inside you will see smoothed up areas with shiny metal where it was ground and polished

my cylinder is stock other than a little bore, i have to get my cylinder bored before i continue. i also have to figure out if im going long or short rod. i did the port maping, but i need to know what im doing before i can continue. its a learning curve that i would like to know. my digital calipers will not fit in the hole, ill look for a smaller pair to see what i got.

[C-LEIGH RACING]

If your wanting to do some porting yourself, Mac Dizzy will be the best place to learn from.
Will take some reading & time to get it all down & perfect, but will be worth it in the long run.

What year cylinder do you have, or year engine.
Neil

[1promodfan]

Originally posted by DEERCHOOPER
that means,

i hope c-leigh would chime in.

Duh!! Now I feel like ret@Rd!!

[DEERCHOOPER]

Originally posted by C-LEIGH RACING
If your wanting to do some porting yourself, Mac Dizzy will be the best place to learn from.
Will take some reading & time to get it all down & perfect, but will be worth it in the long run.

What year cylinder do you have, or year engine.
Neil

i have an 86 motor, the jug is off of a 85 atc

[C-LEIGH RACING]

Originally posted by DEERCHOOPER
i have an 86 motor, the jug is off of a 85 atc

With the 86 engine & 85 jug,,, that should mean you have a short rod crank & piston set up but not 100% sure.

Those old 85/86 short rod cranks, you cant get those anymore from Honda, but you can get the Hot Rods crank with the short rod.
You could as well get a replacement rod kit in the short rod version.
Best build would be the long rod crank & piston set up. You could even have the cylinder big bore 310 & still get the new model piston.
Neil

[DEERCHOOPER]

neil, lets back up a little bit here, lol.

i have a 86 motor, that came with an 88 cylinder (no more bore left) but it didnt have a spacer plate under it, so its a short rod crank. i just picked up a 85 cylinder but im not for sure im using it right now, lol.

my big end rod bearing is +.030 play. im looking for a better rod/ better crank and my buddy has boxes of parts from his builds that are new and or little time on them.

so the short end of this story is, i might end up with a long rod or newer cylinder. time will tell when i get to his place and start going threw the boxes and playing lets make a deal.

you said \/
Best build would be the long rod crank & piston set up. You could even have the cylinder big bore 310 & still get the new model piston.

my question to that reply is, can i bore or do i have to get a new sleeve to get 310cc?

[rustyATV]

If you are planning on porting the transfers heavily, you'll want to pass on that 85 jug. You can make a lot of power out of them, but they don't like having their walls thinned up.

See what happened to mine. It was a 265 on race gas and was outrunning LTR450's with my mid range pipe before it let go.

[C-LEIGH RACING]

Rusty, you hardly got any damage at all, normally the whole bottom half of the reed chamber will crack off on both sides.

Hummmm, you must be running the head stay in place.


DEERCHOOPER,

What bore is that new model cylinder on right now. You would be better off if you could use the new model cylinder rather than the old 85.

You would need to have the cylinder sleeved to change it up to the 310 big bore.
Give me the bore size, because I may have a surprize for you if you dont already know about it.
Neil

[rustyATV]

Originally posted by C-LEIGH RACING
Rusty, you hardly got any damage at all, normally the whole bottom half of the reed chamber will crack off on both sides.

Hummmm, you must be running the head stay in place.
l

Nope, no head stay. Went to launch on the drag strip and, suddenly, it wouldn't run with a load. Still broke my heart. Actually, I think Jeff was more upset about it, since this was his work.

[DEERCHOOPER]

neil, i measured the bore and came up with 68.15mm, so i got 68mm piston. this is on the 88 jug, which has porting done, lol. the 85 jug would be .040 over with the next bore.


rusty, that sucks. i dont plan on going hog wild on this i just want to learn the 2 stroke being this is my first one. its a basket case but for the price i cant go wrong. im building my 450r right now and its a matter of buying this cam, bumping up compression, setting the valves and bolt it back together, lol. 2 strokes just seam like an easy job, with the help of this and that it will take off like a rocket. i know theres more to it than getting out a die grinder and hoggin away, just want to learn.

i dont know the best set up for a stock replacement motor, or which combo will work bad arse. i see where everyone goes with the long rod conversion, but to which year jug style is better i dont know.

[C-LEIGH RACING]

Being at 68.00mm & the new model jug, only thing you can do to get some more bores out of the cylinder is to get a cylinder spacer plate & a 68.50mm 85/86 model piston kit.
The old model 85/86 piston goes up to a 69.50mm & then if you wanted to after that, you could get a 86 model YZ250 Yamaha piston in a 70.00mm size.

With a long rod crank, you would need a 3mm spacer plate for the 85/86 ATC piston & a 2.5mm plate if you use the YZ piston.
Neil

[kiesta00]

I'd stay away from running that big of a bore on a stock cylinder. I had 10 kinds of trouble trying to keep head gaskets on the 69.5mm bore.

Good luck with the build!

[C-LEIGH RACING]

Stock TRX cylinder, with a big bore 295 sleeve, is the hardest build to keep the head gasket sealing & not leaking coolant.
I cured that problem with Three Bond #1211 sealant, at least for a season of racing anyways.
Neil

[regg187]

I know a lot of guys that ran the YZ piston and their motors all lived fine. When my bore goes I'm going to that set up. They really moved with the YZ piston in'em