Amateur Woods Saw Modification

[Four Paws]

Well, I am gonna resurect this old post because I am an amateur, and I am going to try my first woods port. I have been reading the archives of threads here, and have been reading Jenning's book. Maybe the master builders could shine some light on 'art' of modifying a saw for stellar woods performance with some cut-and-dry info. I know every saw is different, but there have to be some starting points that can help us rookies get a feel for what needs to be done and where to start.

My saw is a 39.4cc Shindaiwa 416 and currently has a muffler mod. I want to take it to the next level. I have my files, dremel and a full assortment of attachments ready to go. I am going to check the factory squish band in the morning, and will determine if I am going to mill the cylinder. This is meant to be a learning experience for me - I appreciate the help if you will offer it. I am not trying to take over the modification market - I have a job that I am happy with - I just want to learn a new skill, have fun with it and hopefully end up with a better running saw!

 

[sawinredneck]

Sounds like a neat idea, I have wanted to do it my self as well!!! I would suggest you try it for the poulan challenge though, if only because the cost of you're Shinny's replacement parts are pricey if you screw up!!! Pick up a wildthing at a yard sale for 50 bones, what are you out?
I have researched this here and elsewhere as well, seems to me most of the builders move the ports 1 mm up and down, I think I would start less than that. A mm is only .0394 to start with, kinda small, but maybe half, see how it runs then add a little more? I will help anyway I can, but am merely a novice myself, so I have limited knowledge of any of this too, just would like to understand it better myself.
Let me know if there is anymore I can add, or if you need some advice.
Andy

 

[Four Paws]

Sounds like a neat idea, I have wanted to do it my self as well!!! I would suggest you try it for the poulan challenge though, if only because the cost of you're Shinny's replacement parts are pricey if you screw up!!! Pick up a wildthing at a yard sale for 50 bones, what are you out?
Andy

Andy, my 416 that I am going to modify cost me a whopping $30. The damn thing was so filthy, the owner thought it was beyond hope. A few hours with my allen keys, screwdrivers, a couple cans of carb cleaner, a pile of rags and some compressed air, she was looking as good as new. Put back together, with a shot of fresh gas (after cleaning tank, or course) she fired up on the 3rd pull...I was amazed, and happy! SO, I scored a great saw, for less money than a crappy Wildthing! And, although parts are expensive, if I go slow and take my time, hopefully I won't have to buy parts and will end up with a saw I actually WANT to keep! And, if I mess up...I will spend the $50 I saved on the Wildthing to buy new parts - at least they are available without having to buy an entire parts saw

As far as the raising/lowering the port - I do remember seeing that in a thread, just can't find it - perhaps I need to polish my searching skills.

 

[046]

four paws... look up back posts for gypo logger
he recently posted a few threads on how to mod basics

 

[sawinredneck]

Good buy on the $30, didn't realize that, grind away my friend!!!!
Better call on Gypo 046, he has all kinds of information out there Four Paws, you can spend days researching this, I have.
Andy

 

[buck futter]

I am a porting advocate. However be very cautious, any thing you do, run it through here first and don't be afraid. I know enough of the basics to be dangerous. You may not need to mill the base at all just eliminate the gasket, before you begin work get a good squish band reading. When you get a little deeper into it, it is also wise to find what the stock duration is. For a starting point measuring the squish band is fine. Get it as clean as possible before opening it at all up of course. you may want to take off the front handle just to make it all easier. Once it is apart you will want to remove the ring, oil up the piston and cylinder and put it back together so you can remeasure the squish simulating the base gasket being removed. You could measure the gasket thickness and subtract it from the stock squish, but being the gasket is soft you will not get as accurate of a measurement. The target area for the squish band clearance is .018-.022 " If you read some posts back this spring, there was a big who haa back and forth about porting. Timberwolf had said, " before you start you need to have a plan for the whole saw." I think this is true and very important! make many measurements and document everything. The plan should be like this, you know that you are moving the cylinder down lets say .020, this will give you less transfer and exhaust duration. At the very least move the exhaust up the same amount, widening the port to about 62-66 percent of the bore diameter will also be a huge help. You simply can't go wrong by having the squish a .020, raising the exhaust the same amount and even .010 more and widening the exhaust to 65% of the bore. Most of the intakes I have seen have been full of casting flaws, smooth them up the best you can and widen minimally maybe .020 on each side. You can move the port down some but it already has an increase in duration when the jug is lowered. You can do as Ed said earlier. raise the top of the intake to match the bottom of the piston skirt when the piston is at top dead center.
One of the most important aspects of this whole thing is to ensure that the port corners have a nice gradual transition from the top to the side and also that the edge of the cylinder wall has a nice chamfer on it. Other wise it will catch the ring or score the piston.

I am excited for you to begin, I would like to find a little saw of the same size to play with, I am sure I will at some point.

Any questions don't hesitate

Buck