New to Porting. Have a question on squish

[BigRed96]

Good Day All, I’m new to porting. I just finished porting my first saw, a Husqvarna 55. I’m very happy with the results as far as my work goes. I just did the intake and exhaust and didn’t touch the transfers. Squish on that saw without the gasket came in at .030”.
I’ve moved on to my next saw which is a Husqvarna 51. I’m planning to build it for my Dad as a firewood saw. I set my degree wheel up to get the stock port numbers. I check the squish without a gasket prior to getting the numbers. I used .040” solder and it didn’t even touch it. I have to get some thicker solder to find out what it actually is. I bought this saw blown up years ago. First saw I ever played with. Cleaned up the cylinder and put a Meteor Piston in it. I never even broke the saw in. It has sat on the shelf ever since. With a base gasket the saw blew 150 or 160 iirc. So, do I go through the trouble of cutting the cylinder down to drop the squish or should I just move on and port it? I don’t want really high compression as my Dad’s getting older and doesn’t need to tear his shoulder up trying to start a saw.
Btw the stock timing number are as follows:
Exhaust 106* atdc
Transfers 135* btdc
Intake 70* btdc

 

[Ronie]

I don't have a suggestion as far as porting it but you can fold a piece of solder and twist it together and that might be thick enough to measure your squish.

 

[Stump Shot]

Do a base gasket delete and get the exhaust down to around 108 and intake at 72 and leave it there. Widen exhaust port to 65% of the bore diameter without raising it. Keep it at the 108ish number and port it out and match gasket and muffler. Very little if any should be required of the intake port besides some squaring and matching to the manifold and cleaning it up of casting flaws. This along with a good muffler modification, timing advance of 6 degrees, a well functioning carburetor/clean filters etc. should make an easy to start well running firewood saw for your Dad.

 

[BigRed96]

I don't have a suggestion as far as porting it but you can fold a piece of solder and twist it together and that might be thick enough to measure your squish.

Thanks for the idea!

 

[BigRed96]

Do a base gasket delete and get the exhaust down to around 108 and intake at 72 and leave it there. Widen exhaust port to 65% of the bore diameter without raising it. Keep it at the 108ish number and port it out and match gasket and muffler. Very little if any should be required of the intake port besides some squaring and matching to the manifold and cleaning it up of casting flaws. This along with a good muffler modification, timing advance of 6 degrees, a well functioning carburetor/clean filters etc. should make an easy to start well running firewood saw for your Dad.

Thanks for the information! I appreciate it.

 

[Ronie]

Thanks for the idea!

You're welcome, good luck with your build.

 

[BigRed96]

Using Ronie’s suggestion I was able to determine squish is .o43” without a base gasket.

Thanks for the information! I appreciate it.

Do a base gasket delete and get the exhaust down to around 108 and intake at 72 and leave it there. Widen exhaust port to 65% of the bore diameter without raising it. Keep it at the 108ish number and port it out and match gasket and muffler. Very little if any should be required of the intake port besides some squaring and matching to the manifold and cleaning it up of casting flaws. This along with a good muffler modification, timing advance of 6 degrees, a well functioning carburetor/clean filters etc. should make an easy to start well running firewood saw for your Dad.

Hey Stump Shot, I was looking and my exhaust is 106 already so the 108 won’t work. I trying to figure out the best way to mark the cylinder as far as widening the exhaust port.

 

[David Young]

Using Ronie’s suggestion I was able to determine squish is .o43” without a base gasket.


Hey Stump Shot, I was looking and my exhaust is 106 already so the 108 won’t work. I trying to figure out the best way to mark the cylinder as far as widening the exhaust port.

When you pull the gasket it will go down. Most likely to 107

it will also bump comp.

you should listen to ss

 

[Mastermind]

Do you have a right angle handpiece to raise the uppers?

That's where you'll start seeing serious gains.

 

[Stump Shot]

Using Ronie’s suggestion I was able to determine squish is .o43” without a base gasket.


Hey Stump Shot, I was looking and my exhaust is 106 already so the 108 won’t work. I trying to figure out the best way to mark the cylinder as far as widening the exhaust port.

You should get close to 108 deleting the gasket, Might be 107, 107.5 whatever it may be isn't the worry, that you're going in the right direction is. If starting wasn't an issue, I'd say have it machined, but that could take your saw right out of parameters from the onset. Don't worry too much about squish, if it's .020" to .030" it will be fine for your Dad to start.
I know all this as I built a saw just like this years ago and it ran right well. Could it have run better with more work done to it that I didn't have the capability of doing at the time, yes, I'm quite certain it would have.

Do you have a right angle handpiece to raise the uppers?

That's where you'll start seeing serious gains.

I took from his opening statement that he had not. If this is not the case then they should be considered as well, like you say.

 

[Mastermind]

I took from his opening statement that he had not. If this is not the case then they should be considered as well, like you say.

Before I had one I managed to raise the uppers with a cut off wheel.

It works.

 

[Stump Shot]

Before I had one I managed to raise the uppers with a cut off wheel.

It works.

I tried that later on, once...

 

[Stump Shot]

There are or at least were some inexpensive air right angle that work so so on eBay that will get a bit better job done. A 3mm diamond ball while slow will keep running and not go berzerk on ya.

 

[BigRed96]

When you pull the gasket it will go down. Most likely to 107

it will also bump comp.

you should listen to ss

I already took timing numbers reading with the gasket removed. I am trying to listen to him.

 

[BigRed96]

Do you have a right angle handpiece to raise the uppers?

That's where you'll start seeing serious gains.

No Sir. I’m using a dremel with the flex shaft attachment. I would like to get a right angle piece someday but can’t swing the price of a Foredom unfortunately.

 

[BigRed96]

There are or at least were some inexpensive air right angle that work so so on eBay that will get a bit better job done. A 3mm diamond ball while slow will keep running and not go berzerk on ya.

I will look into these.

 

[Tractorsaw1]

Before I had one I managed to raise the uppers with a cut off wheel.

It works.

While a bit scary, this was my best cylinder - raising uppers with a cut off wheel - seems like I need to start doing some more of this...

 

[Mastermind]

While a bit scary, this was my best cylinder - raising uppers with a cut off wheel - seems like I need to start doing some more of this...

It works. Just slow.