Basic Porting and Polishing Techniques

[Gypo Logger]

Simon sure seems to know the little details....

here's my porting setup with assortment of carbide bits, forward exhaust die-grinder and rear exhaust snap-on die-grinder

prefer grinding off all the ruff casting marks, then polish smooth.

Great picture of the die grinders 046. Glad you have had experience with the car motors, it will be invaluable I am sure in your endeavours with 2 cycle. Although they may be easier to work on due to the size of the cylinders, I bet a mistake is much more costly.
John

 

[Gypo Logger]

Thanks Gypo for all the info keep it coming! I'm starting my third 066 project saw and was looking for someone who would open up! HA Ha about the porting process. I recently ported and polished a 2.3 ford 4-stroker head and intake manifold for a friends pulling garden tractor, what an improvement in Horse power! You can also get a good porting kit from Eastwood company at www.eastwood.com. I was always a little un easy about modifying 2 cycle ports. I feel better now! thanks The Hoosier!

Hi John, thanks for the link to the Eastwood Co.
I'm really liking this porting of these 2 cycle motors. It seems that with patience and the right tools that porting is much easier than learning to file a chain. All we need are the basic and conservative figures and a few good people behind us to help with prior experience.
Your 2.3 Ford project sounds very interesting. Here's a stock 272 barrel I will be porting next. Note how rough the casting and the edges are.
John

 

[trimmmed]

John that's a nice cut off head. When did you start cutting off heads for your saws??

Marky, Your looking at the bottom of the cylinder in that pic.

Marky was correct.

Fred

On second look you right. I didnt see the transfer off to the left and thought it had the same style jug as a 044 or a 395.

Looks like the bottom of the jug to me, what am I missing? :bang:

 

[Gypo Logger]

It is the bottom of the jug trimmed. I thought that was obvious?
Thanks for straightening it out for those that were confused.
John

 

[Freakingstang]

Hey John, I like the pics and information you are saying here. I believe, that there is always a learning experience with differant cylinders/heads. I come from the car back ground and have ported many heads and intake in high horsepower applications...yet these little two strokes kinda scare me

I think the information in this thread is a little better than the one where you removed matrial from the piston skirt. I have found that raising the exhaust port raises the powerband, but what does lowering the intake port do? What about the transfer ports? Do you want them to hold more volume, or as little as possible?

i am working on a couple cylinders right now that are trial by fire, a 55 (closed port) and a 365 SP (closed)

When you make changes, do you do one thing, and then test, or do you do the entire job and test? I try to make minimal changes, then assemble and test in the same piece of wood as before. Keep up the good work


Steve

 

[Gypo Logger]

Very good questions Steve. When we raise the exhaust we are also sacrificing the volume of gas/air at TDC, however, the gain is greater than the loss. We can correct the compression loss by either turning down the base of the barrel or removing the base gasket and replacing it with a thinner gasket.
Lowering the intake increases the duration that the port is open, thus facilitating a larger charge of air/fuel to enter the crankcase.
I usually do all the ports and then test, but doing it step by step and testing may be better although more work.
John

 

[Mange]

Good thread, John!!!!!!!!!!!!

 

[bwalker]

Looks like the bottom of the jug to me, what am I missing?

It sure does in that last pic.

 

[Gypo Logger]

Here's a cuttoff head of an 084.
John

 

[04ultra]

The pictures are looking good Gypo...

 

[ned coed]

porting two strokes

i found when porting my two stroke racing yamaha,s (25 years ago i must add) that the best tool for porting work was a flexy foot controlled arbour. cutting speed for best results was approx 16,000rpm with hss multi edged cutters of various sizes and shapes they were,nt cheap but they would eat alli or the steel liner with equal efficiency. regards to all, NED.

p s just found this site- it,s a fantastic source of information, more power to it.

 

[ned coed]

Porting Two Strokes

hi again just reading through some past threads on porting. to the inexperienced out there a cautionary note. when you alter the the top or bottom edges of ports you are in effect altering the phase timing of the engine ie in four strokes it would be the equivalent of reprofiling the cam lobes so be carefull and remember each port edge should have no burrs,round the edges with a very fine carborundoum stone and try not to alter too much, especially the transfer port entry angles into the cylinder as this could drastically effect the scavenging phase in the cylinder. regards, NED.

 

[troutfisher]

Use a front-exhausting CP mini-die-grinder. Put about 3 cc's of ATF in the inlet for each port you cut, it will lube the carbide burr as you work. Here is another tip for you junior; cut the head off a 1/4" X 2" capscrew. Slice it down the center 1". You can now tear a 3" long piece of emery cloth roll and install it in the slot twisting it clockwise to give you a very nice polishing tool. I use 240 grit. The nice thing about this set-up is as follows: it is aggressive at first allowing you to profile and perfect your surface, as it plugs up with aluminum, (and ATF), it effectively becomes 400 grit, 600 grit and almost crokus cloth at the end. Your finish will be mirror-like. Cheers.

That's a pretty good trick with the 1/4" bolt and emery cloth, I'll give that a try!

 

[blsnelling]

I got a piece of 1/4" aluminum rod from Lowes. That way when I accidentaly go through the paper, I don't tear up my work.

 

[brncreeper]

That's a pretty good trick with the 1/4" bolt and emery cloth, I'll give that a try!

That is a good trick! Those capscrews are plentiful and would make a good polishing tool. The one inch slot would be a little tricky to cut.
Kinda off topic but I wish Simon would give us a picture of his dyno with a chainsaw on it sometime, I think that would be kinda cool.
Here's to Gypo and all his long lost posts!

 

[troutfisher]

I got a piece of 1/4" aluminum rod from Lowes. That way when I accidentaly go through the paper, I don't tear up my work.

Aluminum is a good idea too, I'm sure steel would dig up a jug if it made contact. Brass would be an option too.

 

[Austin1]

I think the older threads on here were better than the newer ones?
Sorry that's all I got!opcorn: Less band wagon jumping and more info for us dummies like me to chainsaws. I have used saw's for a long time but only recently have been interested in modding them.

 

[Tree Sling'r]

I got a piece of 1/4" aluminum rod from Lowes. That way when I accidentaly go through the paper, I don't tear up my work.

I use a 3/8 wooden rod, cut a slit in the middle, run my emory cloth through it and run it in a drill on the fastest speed. Fast enough to finish and polish and not enough torque to break the dowel. Then again, if it does break I have another two feet and it was only about $1.50 anyway. I have used the same dowel for over a year and probably 60+ saws.

 

[046]

getting ready to port and polish a new 026 cylinder... how much do I need to raise the exhaust port and lower the intake for a woods port. do I need to leave off base gasket to compensate for decreased compression?

or shall I widen ports only and leave changing the timing alone?

got a lathe and mill, if machining is needed.

Chainsaw Master, as an alternative to the ink and scribe method, you can also invert a ringless piston into the barrel and take measurements that way.
With an old piston you can cut the skirt after measuring and use it as a template to arrive at the actual height of the port.
As far as the specs it is not an exact science however, experiment with small amounts like .5mm- 1.5 mm. You want to raise the exhaust and transfers while lowering the intake. With some saws I simply lower the intake 1mm and raise the exhaust .5 mm, while not touching the transfers.
It's a fun learning thing and you won't screw up your saw if you don't go overboard. I'm not sure what you mean Whatsnext.
Brian, I have started polishing the ports as opposed to leaving them unfinished because like you I heard there are two schools of thought, but the finished product looks much better when polished, plus Tommy Fales told me to polish.
Ben, that's a good point about the carbon.
Russ, I still use my trusty fingernail file on occasion
John

 

[TJfromCC]

Flattered

Nice work John! Now you`re plagiarizing the inside back cover of the C&C Specialties catalog. I guess that no low is too low when you start at the bottom and then attempt dive deeper.

Russ

Hey man I am flattered.