Spuds Porting and Tuning Thread

[Stubby]

4 hours ago, stihlmadasever said:

My 346xp landed today spud,lookin forward to lettin her rip...

Thanks for your hard work mate

Welcome to the club ........

[spudulike]

17 hours ago, Rich1911 said:

So have you left the height of the arch untouched, not gone any further towards the cylinder top. Just removed material either side and made the arch profile shallow less of the curve.

Yes, the port timing has remained standard on this one.

[spudulike]

5 hours ago, stihlmadasever said:

My 346xp landed today spud,lookin forward to lettin her rip...

Thanks for your hard work mate

You will like it, they get pretty leery with porting and must be one of the best saws to get ported.

[Luckyeleven]

Well, in case you aren't yet aware, spud is the man.
He recently 'fixed' my 365 x torq and put up with my nagging doubts when it turned out to be a mere blocked (but clean looking) air filter.

He then worked his sinister magic and gave me back a wild beast of a saw.

Photo below was of the test run, That particular fell really belongs in the 'stunt fell' thread. wish I had taken more to do it justice.

Thats a 24" bar for scale. In fact I prefer this saw to my brand new 576..... 

[spudulike]

Glad you are happy, I could tell that you thought the bad running couldn't be contributed to the oily air filter but there you go. The rest is just....Alchemy

[Luckyeleven]

11 minutes ago, spudulike said:

Glad you are happy, I could tell that you thought the bad running couldn't be contributed to the oily air filter but there you go. The rest is just....Alchemy

I was trying my hardest to let those in the know make the calls! I bowed and continue to bow to your wisdom!

[Rich1911]

Husqvarna 359 porting.  Number 1 of 7

I’ve had to cut this post into smaller sections due to upload file size with the photos. 7 posts in all documenting the process of the rebuild and porting

A few years ago I picked up a cheap 359 that had been trashed when ran on straight petrol. I cleaned up and ported the cylinder, modified the exhaust and carb and was very surprised at its transformation, so much so it’s been my go to saw ever since. I’ve been meaning to rebuild another 359 to the same specification. I started the rebuild a couple of weeks ago.

With the exception of new bearings and an OEM cylinder kit purchased from the US all the other bits are from my parts stock of husky 357’s.

Chassis/Crankshaft

I’ve replaced the crankshaft bearings with new SFK 6202 C3. Crankshaft in the freezer overnight then the bearings heated up on my soldering iron, I rotate the bearings with my fingers every 30 to 40 seconds to evenly distribute the heat until I start getting blisters from the heat (only joking) I know they are ready when the bearing get too hot to touch. Then quickly slide the bearing on the frozen crankshaft (wearing gloves). I use the soldering iron as heating bearings in the oven is more hassle, the soldering iron is easier and quicker. I’ve left the stuffers on the crankshaft. The stock 359 saw doesn’t have stuffers, but I’ve adding them as I feel the reduced volume in the crankcase enables the fuel oil mix to be forced into the cylinder at a higher velocity and subsequently the exhaust gases leaving the saw at a higher velocity, theoretically keeping the cylinder cooler and ultimately prolonging it’s life.

The Crankshaft and bearings go back into the freezer for a couple of hours

Then when the boss is out of the house I put the cleaned crank cases in the oven (oven is not preheated) I let the oven heat up to 180 -190 centigrade and let the cases soak up the heat and expand for 10-15 minutes. I then take one crankcase side out and drop in the frozen crankshaft after making sure I put the correct crankshaft side in the, whilst the other crankcase side is still in the oven I’ll fit the gasket and case guides around the crankshaft and case I’ve just put together. I then place a piece of aluminium flat bar on the gasket, take the other case side out of the oven and drop it onto the bearing on the other crankcase side. The flat bar stops the crankcase dropping too far over the bearing as you’ll never line up the case guides first time.

Then it’s a matter of removing the flat bar, dropping in the 6 crankcase screws and alternately tightening these one turn at a time up until the two halves meet. I don’t use any thread lock on the crankcase bolts.

Then destress the crankcase bearings, I add a clutch nut to the clutch side and flywheel nut to the flywheel side then give them a tap with a copper mallet either side to free the bearings in the bearing cases.

Next installing the oil seals. Both sides are done the same way, isolate the piston top arm ( a piece of wood slid either side of the piston arm) oil the seal I use 2 stroke oil and drop some oil into the exposed bearing, slide the oil seals over the crankshaft until they rest on the crankcase then I add a series of oversized washes/spacers until the crankshaft is covered just beyond the screw threads. Then the easy bit, I start to slowly screw down with either the clutch nut or a flywheel nut to press in the oil seal to the crankcase, the oversized washer limits the depth the seal is pressed in. Then unscrew and remove the washes, perfectly seated oil seals every time.

 

[Rich1911]

Husqvarna 359 porting.  Number 2 of 6

 

 

Exhaust

I drill a series of 2mm holes around a large section of the internal baffle via the cylinder side of the exhaust, I’d drill the holes progressively larger until all the holes meet. Then remove the section of baffle and clean up the rough edges inside the exhaust with a chain file, it’s a pain of a job to do but I think the benefits outweigh the hassle.  I then just I drilled out the existing exhaust pipe, enlarge the hole and braze in a larger pipe, clean up the outside of the exhaust of brazing flux. See the photo comparing the two exhausts showing the difference in exhaust pipe size I’ve done the math and there is an increase in exit hole area of over 60%.

[Rich1911]

Husqvarna 359 porting.  Number 3 of 6

 

Porting the cylinder

The idea is to increase the velocity of the fuel oil mix around the cylinder and exhaust gases by reducing as much as possible any obstructions to this flow. The tools I use for this is a Dremel and some tungsten carbide grinding bits.

The trick here when removing material is to not force the grind but let the tool do the work, remove small amounts at a time and constantly check your work. Grind up to your markings and never be tempted to grind that little bit further.

1 open up the intake port on the cylinder. Both intake and exhaust ports are widened to around 70% of the cylinder diameter. The 359 cylinder diameter is 47mm so I widen the ports to around 32mm. I’ll not alter the top or bottom of the ports just widen the sides.

2 as much as possible blend in the lower cylinder skirt to match the crankcase, on the Husky 346, 357, 365, 372 non torq saws removal of the cylinder material is straight forward and can be matched perfectly. The 359 is more of a challenge as the side transfer plates can be removed and you’re limited to keep enough material to not compromise the screws holes that hold the plates on and to maintain an air tight seal when assembled.

The plus side of the 359 is that removing the side transfer plates gives better access to clean up the transfer ports and model the transfer dividers to influence the direction of the fuel oil mix. By removing a corner of the divider the flow of fuel can be channelled to the back of the cylinder pushing the exhaust gases out faster. I prefer to change the shape of the dividers on both the cylinder and transfer plate to help with the flow rather than remove them all together. I’ve also removed material from the lower part of the transfer ports but left the upper transfers as is, my logic being I’m creating a funnel type effect, the same volume of fuel air mix being sucked up a narrowing area again increasing the velocity of the mix.

[Rich1911]

Husqvarna 359 porting  Number 4 of 6

 

3 Widen the exhaust port and also enlarge the exit channel. I then offer up exhaust gasket and heat shield to the exit channel hole and enlarge the hole until they match the cylinder. Then transfer the gasket to the exhaust, mark the hole against the exhaust and enlarge the exhaust intake hole accordingly. I can then give the exhaust a final clean and then spray with stove paint and bake this on with a heat gun.

The cylinder intake and exhaust ports are smoothed inside with 400-600 grit wet and dry. It’s given a thorough clean to remove any aluminium debris from porting and the side transfer plates put back on. I used the existing gasket and also Loctite 518 to ensure an air tight seal.