Thread: Let's talk about porting...
11-09-2009, 08:08 PM #1
Let's talk about porting...
In an attempt to stimulate discussion and possibly learn something along the way, lets discuss the effects of porting a cylinder, what to do, what not to do, and personal experiences. We all have heard that porting a cylinder has a similar effect as changing the cam in a 4 stroke engine. And just as there are cams for low end torque and cams for top end horsepower, there is an equivalent when it comes to porting 2 stroke cylinders. Any responses to the discussion is appreciated, we all may learn from this.
To start this off, lets discuss exhaust ports. What should be left alone, and what can be changed. What gives better low end torque, and what gives better horsepower. I know you can raise the top edge of the port, widen the port, and change its shape entirely, but what does each of these things do?
11-09-2009, 10:28 PM #2
Search the yamaha 2 stroke section, lots of porters on there
11-09-2009, 10:51 PM #3
How similar are the Yamaha 2 strokes compared to the Polaris 2 strokes? I know the theory of cylinder porting is the same, but is it like comparing apples to apples, or is it more like comparing fruit in general?
11-09-2009, 10:55 PM #4
There are so many variables. Each different engine/cylinder i get i measure them up and run the software and CAD to develope the best power i can get. Some dirtbikes ive done had exhaust ports from the factory that had too much EX TA ( exhaust time area). Port shapes, heights,widths, transfer port openings at TDC all play the role in making the maximum power available. The computer software tells me were i am on that particular cylinder so i can make the proper changes to make the best power. Believe me, its WAY more than just a Dremel and bit, and just taking a little out here and there, like your gutting out a pumpkin.
11-10-2009, 06:47 AM #5
11-10-2009, 09:18 AM #6
11-10-2009, 06:28 PM #7
- Join Date
- Aug 2006
- Homer Glen Il.
Porting is an art there a very few people out there who truly know what they are doing ,so be careful
11-10-2009, 06:37 PM #8
Okay, so porting cylinders is best left to the professionals. What about things like exhaust manifolds, intake manifolds, etc. These things don't affect intake/exhaust timing, but are they still as critical as cylinder ports?
11-10-2009, 07:05 PM #9
11-10-2009, 07:19 PM #10
Last edited by WATER WOODY; 11-12-2009 at 01:34 AM.
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