Husky 272xp CFB style

[Canadian farm boy]

A few weeks back I was contacted by fello OPE member @CJ Brown. He had a freshly rebuild husky 272xp and wanted it ported. Arrangements were made and he delivered the saw to me along with a few brand new extra parts.

 

[Canadian farm boy]

The saw was built around a brand new set of AM cases. Chris had a couple small clearance issues when he rebuilt the saw but they were nothing that a little grinding and fitting couldn't take care of.

 

[Canadian farm boy]

I got to work on the saw and my first order of business was to check the stock squish numbers and port timing.
I checked the stock squish with a .020 base gasket and measured a tiny .013". Without a base gasket it was a head slapper.
Stock timing numbers with a base gasket were
104/121/71.

 

[Canadian farm boy]

I contacted a couple members here and did a little brain storming @rattler @Stump Shot @drf256
Thanks for the advise and tips guys. Now armed with a bit of knowledge of this saw and some insight from these great guys I concocted a plan and proceeded to execute it.

 

[Canadian farm boy]

My first order of business was to cut the cylinder base and squish band.
With the saw having such a tight squish to start with I cut .015 from the cylinder base and extension and .020 from the squish band. This gave me squish clearance of .018 with a .020 paper base gasket

 

[Canadian farm boy]

I sanded the squish band and set my squish at .020

 

[Frank bierce]

Just love build threads like this!!

 

[Canadian farm boy]

Having the cylinder all machines and my squish clearance set I got to work at making it breath a bit better. Decided I'd go with ported timing numbers of 102/121/78. The upper transfers were nearly perfect. All I needed to do with them was clean them up a bit.

 

[Canadian farm boy]

Here's a few pictures of the port work.

 

[Canadian farm boy]

More port work pictures. I should note that the intake and exhaust ports were widened to within .080" of the piston skirt width. The inlet of the intake port wasn't touched. It's a perfect match to the intake block.

 

[Canadian farm boy]

@CJ Brown supplied me with a used oem 272 piston and a new meteor piston. I took various measurements of both pistons and compared. I didn't get pictures of my measurements but the 2 pistons were within .001" in every dimension that I measured. I even measured the thickness of the circlips. They were identical. I used the oem piston for all mock ups as I didn't want to risk marking up the brand new meteor.
This is where I had a little fun. I weighed both piston assemblies. The piston, ring, wrist pin and circlips.
First picture is the oem, second picture is the meteor.

 

[Canadian farm boy]

I noticed the meteor piston has some casting flash and a few rough edges around the piston windows. Knowing that the meteor piston assembly weighed a touch more then the oem I proceeded to smooth things out. I did not do this with the intention of lightening the piston but with the intention of making the surfaces smoother. When I was finished I reweighed the piston assembly. I was pleasently surprised. The meteor piston assembly now weighs the same as the oem. If you look closely at the picture you can see a bit of the clean up work I did.

 

[Canadian farm boy]

Piston installed and ready for the cylinder. Chris supplied me with a new set oem circlips so I used them rather then the meteor supplied clips.

 

[P.M.P.]

CFB Rocks

 

[Canadian farm boy]

Before installing the cylinder I gasket matched the exhaust gasket, heat shield and muffler to the exhaust port

 

[Canadian farm boy]

Did some work to the muffler. Gotta let this beasty breath! Chris wanted screens so I also added some #10 stainless screens.

 

[Canadian farm boy]

Going back together

 

[Canadian farm boy]

With the top end buttoned up I turned my attention to the ignition timing. I filed .020 from the flywheel key.

 

[Canadian farm boy]

Flywheel back on and some more reassembly.
The top cover hugs the muffler really tight and already had a small melted spot from the muffler. I added some heat tape for a little insurance that it wouldn't get worse or happen again.

 

[Canadian farm boy]

Pressure and vac tested. Failed miserably at first due to a leaky decomp button. I ditched the decomp for a plug and the saw passed with flying colours