Degree Wheel Setup

[Mastermind]

http://opeforum.com/threads/chainsaw-porting-theory.1301/#post-58133

 

[Mastermind]

Read more books on the theory of two-stroke motors. Do the math. Read some more. Think about what is happening in an engine rather than rely on people answering your questions first.

Two stroke porting books will lead you off in the wrong direction of you try to apply that knowledge to chainsaw engines. Two different worlds.....

 

[idiotwithasaw]

I have been reading the lets talk transfers thread and it has been very informative. It's a lot to take in, I also have been reading up on 2strokes. Bit understanding how they work isn't the same as understanding what numbers work where and why manufacturers choose the numbers they do and why monkeys in their garage put them where they do.

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[smokey7]

I hope not to come off as a tool looking for everything spoon fed to me. I am enjoying reading and just espressing what I'm hoping to read soon regarding chainsaw motors. As my head is spinning since I'm trying to run in both the pipe world and chainsaw world. I saw the link so I will have to check into it soon. Thanks all

 

[Nitroman]

I have been reading the lets talk transfers thread and it has been very informative. It's a lot to take in, I also have been reading up on 2strokes. Bit understanding how they work isn't the same as understanding what numbers work where and why manufacturers choose the numbers they do and why monkeys in their garage put them where they do.

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Stop fixating on numbers and think what is happening in the engine. One way to do this is pull an old saw apart ( I recommend Husky), have only the jug mounted on one half of the crankcase with the crankshaft and piston still in. This way you can see the relation of the piston and crank to the ports as it moves. You'll need a good source of light too.

 

[skippy]

Ty haus

 

[Glock37]

nope miss that one cuz.View attachment 11670

Now we are getting to the good stuff


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[Nutball]

Bump

I'm using the @Red97 digital degree wheel, it works great and is easy to use, but I can get a degree or 2 difference in port height depending on reading before or after TDC. I assume this is because the magnetic gauge sits slightly off center from the shaft in its holder? Will averaging the 2 readings give me an accurate port height? That's what I've been doing. It seems to work well for finding TDC by using one port for reference, setting zero, then finding duration, divide by 2, set the gauge to read that half way value, then set zero again.

 

[David Young]

Bump

I'm using the @Red97 digital degree wheel, it works great and is easy to use, but I can get a degree or 2 difference in port height depending on reading before or after TDC. I assume this is because the magnetic gauge sits slightly off center from the shaft in its holder? Will averaging the 2 readings give me an accurate port height? That's what I've been doing. It seems to work well for finding TDC by using one port for reference, setting zero, then finding duration, divide by 2, set the gauge to read that half way value, then set zero again.

For a piston port motor it should be fine to divide total duration in half.

 

[Ketchup]

Bump

I'm using the @Red97 digital degree wheel, it works great and is easy to use, but I can get a degree or 2 difference in port height depending on reading before or after TDC. I assume this is because the magnetic gauge sits slightly off center from the shaft in its holder? Will averaging the 2 readings give me an accurate port height? That's what I've been doing. It seems to work well for finding TDC by using one port for reference, setting zero, then finding duration, divide by 2, set the gauge to read that half way value, then set zero again.

I found that the instrument would shift slightly in the housing when I pushed a button so it was always a degree or so off. I drilled and tapped the housing and put a set screw in so that it was held in place. That helped lot.

 

[Nutball]

I might add shim plates