Porting 101

[Mastermind]

I was thinking last night( not always my strong point), for those of us with no easy access to a lathe could you just use a large flat washer to sandwich the degree wheel to the chuck? Seems plausible but I dont have a chuck in front of me just yet. I am going to see if my dad has any dead drills that I can steal a chuck from. He has enough stuff I should be able to find something laying around.

Yes that would work, just make sure it is centered properly. I've got the degree wheel mounted many different ways, a person is only limited by their imagination when it comes to these things. I still use a printed degree wheel on thick card stock. I do make it larger than I did when I started, but I get repeatable results with no problems.

 

[Brian13]

Good deal, I ordered the Summit wheel last night. I have a Husky 55 jug I am going to practice grinding on and then I will move on to my 044/046:msp_smile:.

 

[parrisw]

I was thinking last night( not always my strong point), for those of us with no easy access to a lathe could you just use a large flat washer to sandwich the degree wheel to the chuck? Seems plausible but I dont have a chuck in front of me just yet. I am going to see if my dad has any dead drills that I can steal a chuck from. He has enough stuff I should be able to find something laying around.

If you buy the summit wheel it comes with the adapters and you won't have to worry about it. Just find a chuck and the metric bolt and your good to go.

Yep. Like Frank said they come with different adapters, mine had a couple but they all had a slight amount of play, so why no do it on the lathe and get it perfect. Also here is a tip for you guys. Use a automotive drain plug for your bolt, that's what I did they have a big flanged head on them for the sealing surface and you don't have to use a big washer, looks much better.

As you can see in this pic. Its a very standard thread. I think it might of been 1/2 20

 

[Blowncrewcab]

What is that Blue thing Mounted back by the Handle??

 

[parrisw]

What is that Blue thing Mounted back by the Handle??

Its the ignition coil. Its a 2 piece ignition on a 288xp

 

[tbone75]

great info guys thanks!!!

 

[Mag460]

Lot of good info on porting.. I have a stihl460 I have muffler mud done to it an I have question about porting.. I was thinking of taking base gasket out.. Then cleaning up intake cast marks for better flow.. Now on piston the transfer slots what do u do with them? Also for exhaust port I was gana do little wider an like 1 mm higher.. Would tht be good since I'll be running no base gasket? An for top an bottom of ports they should have little roundness to them an straight sides correct? An keep all intake ports same just make transfer clean an knife edges right?

 

[tlandrum]

you need to do some more searching. your plan sounds like a disaster in the works. dont ever go into a saw and raise or lower anything without using a degree wheel to see where your at and map out where your going.

 

[Chesterewers]

you need to do some more searching. your plan sounds like a disaster in the works. dont ever go into a saw and raise or lower anything without using a degree wheel to see where your at and map out where your going.

Just make the exhaust wider, you can widen intake too, like they say map it out mark it so you don't go too wide, and don't raise or lower the intake exhaust unless you really don't care, it might lose rpm or compression if you mess up, someone on here said they messed up and used JB weld to fix it with success, but the saw he used was either cheap or free, I forget. Anyway another easy way for added power is just to port the muffler. The old stihls 066 076 ect have huge ports no porting needed on those mufflers. Thats before the EPA got all crazy on a little engine. Why not regulate huge polluters, try regulating 3rd world countries to save the air and weather. If you ever been to any where the air is so dark you can't see 1000 yards away very clearly you know what I am talking about buses spew out black diesel, a small engine in the Forrest is a joke, aren't trees healthy from carbon monoxide in amounts able to be used? Anyway sorry for long post, the owner of this site can delete it if they get sick of me.

 

[Mag460]

Ok ill forget making higher or lower.. I was told u could mill it 1mm higher an be good.. An I only taking base gasket out after I check the squish. To get more compression. An of course I'll measure piston skirts an leave the appropriate thicknesses an for rings. On exhaust could u go 1 to 2mm wider depending what I aloud after I measure, could u go wider where muffler bolts on?

 

[parrisw]

Ok ill forget making higher or lower.. I was told u could mill it 1mm higher an be good.. An I only taking base gasket out after I check the squish. To get more compression. An of course I'll measure piston skirts an leave the appropriate thicknesses an for rings. On exhaust could u go 1 to 2mm wider depending what I aloud after I measure, could u go wider where muffler bolts on?

Put the piston on with no rings. Bolt the cylinder on with a couple of bolts, get a very fine point pencil so you can get right out to the edges of the port, and mark the port sides on the piston, oh degrease the piston first so the pencil will take. Now take the cylinder off and measure from the pencil line to the edge of the piston skirt, how much you got? Now widen to .100" to the skirt edge. I would also make sure that the total port width after doesn't exceed 65% of bore width. When you widen, make the sides of the port vertical, and blend it out and up to the roof of the ex port without raising it.

 

[half_full]

Wow, I just made it through all 23 pages of this thread. 15 and 16 were skipable...
I have been playing with a "can't lose" (big scratch, low comp.) P&C for my 372 and found a few things I did wrong. Oh well. Still be interesting to see if or how it runs and learn.

So, in the few threads I've read through I see to polish exhaust and leave intake alone or rough cut it only. Why is this?

 

[sun64]

There are probably better people on this site that can explain it better than me but here goes.
With a polished exhaust port, there is less drag from the escaping gasses on the sides etc which will lead to less back pressure and faster gas removal out the muffler.

With a semi course intake port, if it is slightly rough the fuel leaving the carbie will spray onto the intake faces and be picked up by the incoming air charge. It will lead to a better air/ fuel mixture in the crank case.
If you highly polished ther inlet port , the fuel would have a tendancy to run off the polished sides and into the crank case and will not have mixed properly for the next charge into the combustion chamber.
It is better to leave them slightly rough but without any casting flaws, lips etc
Hope this helps

 

[vals poeticus]

hi all

hi..im vals from jakarta an two stroke lover,would you all mind what is the first you want to do to build a drag two stroke,i ve kawasaki ninja 150 cc and yamaha 135 rx king both are two stroke,all i want to know is how to port,polis,cyilender etc count,i read the many books and i dont understand till now:hmm3grin2orange::hmm3grin2orange:,if you can help me in the very simple languange...tennkyouuu alll!!!

 

[Hddnis]

hi..im vals from jakarta an two stroke lover,would you all mind what is the first you want to do to build a drag two stroke,i ve kawasaki ninja 150 cc and yamaha 135 rx king both are two stroke,all i want to know is how to port,polis,cyilender etc count,i read the many books and i dont understand till now:hmm3grin2orange::hmm3grin2orange:,if you can help me in the very simple languange...tennkyouuu alll!!!

Mr. HE

 

[Mastermind]

Mr. HE

The art of trolling....... :msp_rolleyes:

 

[thunder saw]

hi kinda new here. was wondering if im on the right track with my exhaust port. still need to smooth it out some. thanks.

 

[shorthunter]

Few pictures of my Sachs-Dolmar 143. The transfer ports were a PITA, everything else went as planned (for the most part). I also ported the intake to smooth the transfer between the carb and cylinder and I port matched the muffler to the cylinder and opened the exit port about 30%. Maybe I can get a video of the saw running in the next day or two

 

[shorthunter]

Video of the 143. This was the 9th or 10th test cut after the rebuild. You will notice that the saw starts to run out of fuel 3/4 of the way through the cut. 34" bar spinning .404 chain, 7 tooth sprocket

 

[Mastermind]

The port work you have done here have not made enough difference to run the saw out of fuel. You have other stuff going on.