Amateur Woods Saw Modification

[YUKON 659]

First things first, I don't race saws and I don't even know a whole lot about building them, but I'm a pretty good machinist and I had the desire to do some sort of modification to my saw other than just a basic muffler job. With that being said, I was assisted by one of our resident "magicians" and worked some magic on my Husky 288 Lite.
I started out by machining .020" off the base of cylinder. I have a picture to show the set up I used. I raised the exhaust port .010" from it's original height and widened it about .080" in a CNC mill. I also polished it to a mirror finish.The intake port was glass beaded to obtain a slight texture. The last thing I did was a muffler modification as you can see in another picture.
I haven't made any cuts with it yet but as soon as I do I'll let you know how it does. It seems to have incredible throttle response and there is a definite difference in the way it runs...seems like the effort was well worth it!!!!

Jeff

 

[YUKON 659]

Here's a picture of the muffler before modifying it...

Jeff

 

[Marky Mark]

I hope you bring it to the GTG.

 

[scottr]

saw mod

Jeff , nice work . What will the exhaust port work do to the power band and what is the exhaust port area to muffler outlet area ratio ?

 

[YUKON 659]

Scott, I'll let the experts answer the question about the power band, like I said, I'm not a builder I just did the work..if that makes any sense. As far as the exhaust outlet, I'd say it's about 85% of the exhaust port. I didn't want to go to big at first.

Jeff

 

[scottr]

muffler cover

Were you able to use the original muffler cover or did you make a new one ?

 

[ehp]

well you might as well do your intake port and the transfer ports because when you lowered your jug you changed the porting time on them as well, when you lowered the jug you have to remember that you need to port the top of the intake port so that when the piston is at top dead centre the bottom of the skirt doesnot go up pass the top of the intake port because if it does you have port timing that is doing nothing because the port is blocked at the top from the intake port not being level with the botton of the piston skirt

 

[bwalker]

And what ever you do dont make that squish too tight......

 

[ehp]

Why Ben what happens when you get the squish to tight

 

[YUKON 659]

Scott, I removed the back deflector and turned the front one around. It needed to be bent a little to fit right though.

Jeff

 

[Crofter]

Yes, Jeff, make sure you don't turn your squishy squish into thunkety thunk!

 

[YUKON 659]

Ed, I would've liked to do the transfer ports but I do not have the right tool to get in there and do it. Just doing the exhaust port was challenging enough. I was able to get in and chamfer the exhaust port (top & bottom) through the plug opening and from the bottom of the cylinder. I broke the exhaust port sides through the exhaust port itself. I used a die grinder with a diamond impregnated Borzon wheel in it.

Jeff

 

[YUKON 659]

Squish is fine...about .025"-.030". Like I said the saw runs great and I'll hopefully be cutting some wood with it this weekend. I need to remove the ears on the limiter caps...saw seems to be running a little lean after the work that was done.
I don't own a tach. but now might be a good time to get one.

Jeff

 

[ehp]

You could of put a little bevel on the top of the piston to gain back the tranfser timing but you already ported the ext.
you said you lowered it .020 then raised the ext. port .010 so you could cut the piston to gain back the tranfser numbers, with the porting lower on the tranfsers you will get more torque at a different rpm

 

[Al Smith]

Good for you Yukon.This topic just came up another thread.Atta boy,be a doer

 

[bwalker]

Why Ben what happens when you get the squish to tight

Squish turns to squash.

 

[YUKON 659]

I finally got around to removing the ears from the limiter caps today and made a few quick cuts with the saw. I'm sure the carb. still needs a little tweaking but it definitely has more power than it did stock. I was cutting some Norway Maple (kinda hard I guess) about 16" in diameter and I could really lean in to it with out the saw coming out of the power band. Not sure how fast it is but it seems to have lots of torque, which is what I was looking for.

Jeff

 

[kf_tree]

i have a stock 288xp you could compare it against at the gtg

 

[YUKON 659]

Sounds good...I'd like to see how it compares to a stock saw. Any muffler work done to yours or is it bone stock?

Jeff

 

[kf_tree]

bone stock.........saw has been used for about 5-6 years now. i'd love to get my hands on another one. i saw a nice clean one on ebay.....but the buy it now was 600.00 and reserve was 549.00. way too much for a used saw. no one bid on it so i sent him an email asking him to let it go for 400 with shipping but he didnt bite.