Two Stroke Porting

O

ossagp

You see the guys that know that one do it and you will never believe it is worth it. You have the block and the head to deal with. Valves in, and then out, head off and then back. Manifold off and on. No wonder you can spend thousands. Hell, you can buy a new set of Dart aluminum heads for any overhead and go into second mortgage territory to win a circle track race that doesnt pay enough to fuel the race car and two car if you are 60 miles away from the track.
 
Mihylo33

Mihylo33

ossagp:
I deal with vacuum all day long. Consistent and being able to get "leak free" is the key. I feel.

I have seen lots of cylinders that flowed well (most won't know that "well" really means) and the bike was slower than stock. If you have someone that claims he knows porting and tells you it is about reducing vacuum and doesnt mention the relationship with maintaining volume or what some think of as the ratio between lost vacuum and gained volume it may be time to shop for your porting elsewhere. Timing to me has been more important when it comes to ports than anything else. It is really pretty amazing what a small change in stroke can make. Maybe my next shot at building a fast(er) 500?
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Not so much how it flows as when it flows when you need it to.
 
bobkyle2

bobkyle2

ossagp:
You see the guys that know that one do it and you will never believe it is worth it. You have the block and the head to deal with. Valves in, and then out, head off and then back. Manifold off and on. No wonder you can spend thousands. Hell, you can buy a new set of Dart aluminum heads for any overhead and go into second mortgage territory to win a circle track race that doesnt pay enough to fuel the race car and two car if you are 60 miles away from the track.
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I'm lost.
 
O

ossagp

Mihylo33:
Not so much how it flows as when it flows when you need it to.
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Yeah, it used to be pretty common to see guys claim that you wanted to get the most through each transfer as possible etc. So just make it huge again. The next big fallacy was in matching. Most matched by bringing the "slow side" up to the fast side. So you had two fast sides, and lots of times a "slow" bike.
 
Mihylo33

Mihylo33

ossagp:
Yeah, it used to be pretty common to see guys claim that you wanted to get the most through each transfer as possible etc. So just make it huge again. The next big fallacy was in matching. Most matched by bringing the "slow side" up to the fast side. So you had two fast sides, and lots of times a "slow" bike.
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Matching the cases is where the real ponies hide.
 
O

ossagp

Mihylo33:
Matching the cases is where the real ponies hide.
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I think it is about the only safe place for the average guy to find something. It is pretty much free while you have the cases split. I just find it amazing that so many seem to think the gasket is always right. On some rigs your time is better spent filling to match than grinding. That area really isn't a tightly contained flow.
 
Mihylo33

Mihylo33

ossagp:
I think it is about the only safe place for the average guy to find something. It is pretty much free while you have the cases split. I just find it amazing that so many seem to think the gasket is always right. On some rigs your time is better spent filling to match than grinding. That area really isn't a tightly contained flow.
Click to expand...


Port polishing is a good one too. Cuts down on turbulence cheap and easy to do unless you knick the nikasil...
 
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