Tzed250's Husqvarna 550XP

[Tzed250]

What kind of wood is that? The saw's really charging through it! I can't remember....did you port it?

It is Catalpa, a relatively soft wood. The saw only has a muffler mod. No port work....yet

 

[Tzed250]

And now ported it is! I started by measuring the stock squish, and I was quite surprised to find it at .037". After seeing that there was plenty of room I decided to see if I could get away with just removing the base gasket. A quick check showed that the squish was .015 with no gasket. Too close for me. I had made a mandrel for this saw in case I had to cut the base. I affixed some wet-dry to the face and trued the squish band same as I did in my MS660 Superstock build. I dropped the cylinder back on the saw and the squish measured .02". Perfect for me. I took the cylinder back off and went to work on the ports. The removable transfer covers make the job easy. I didn't remove that much metal, the largest change being that I put the transfer roof on each side back to the original timing. The exhaust roof had a significant lip on it so I tried to blend and smooth it. I barely widened the exhaust, and I angled the transfers toward the rear somewhat. I cleaned up the intake just a little, but I did nothing to the strat ports. As I have said before, I like the way this saw runs and I just wanted a little more.

Before I started today I knew I needed a new log, so I set one up and shot a before video:

<iframe width="588" height="441" src="http://www.youtube.com/embed/VTwb8HsTDq4" frameborder="0" allowfullscreen></iframe>



The after video. The saw is not going to idle as it should. I hope this is the AT still learning the port work. Best I can tell the saw gained ~21% from the muffler mod, which itself gave a ~22% gain. I wish I had a tach. This saw is revving its guts out, loaded, in the wood.

Remember folks, 50cc:


<iframe width="588" height="441" src="http://www.youtube.com/embed/vs_klHb5R48" frameborder="0" allowfullscreen></iframe>

 

[mweba]

Did you check the bevel at the base, John?

 

[Tzed250]

Did you check the bevel at the base, John?

My measurement showed I had .015 clearance.

 

[mweba]

My measurement showed I had .015 clearance.

This bevel marked with sharpy.

 

[Tzed250]

Yeah, that radius. I ran a swivel knife around the corner on the cases to chamfer them. May not have gotten it enough. If not I will cut a relief on Monday.

 

[Mastermind]

I didn't average the cuts because you were varying the pressure but it looks like you made some very good gains with the port work John.

 

[parrisw]

Wow, I think you got a good one there.

 

[SierraWoodsman]

I Wish you had a Tach too! Had to be running 10500-11000 RPM Under load.
It sure didn't slow down much when you hit the wood.
That was Impressive. Is that running with .325" full comp chain?

 

[Tzed250]

I didn't average the cuts because you were varying the pressure but it looks like you made some very good gains with the port work John.

I only took the times from the first three cuts in each video. I tried to keep the load the same for those six cuts. Thanks Randy!

Wow, I think you got a good one there.

I Wish you had a Tach too! Had to be running 10500-11000 RPM Under load.
It sure didn't slow down much when you hit the wood.
That was Impressive. Is that running with .325" full comp chain?

Yes, Oregon 20LPX. For as little as I did the gains are somewhat impressive. I never expected it to run that well.

 

[Tzed250]

Cold compression is now at 152psi, up from 130psi.

 

[Mastermind]

Cold compression is now at 152psi, up from 130psi.

It will be interesting to see where it is at after a year.

 

[TK]

I Wish you had a Tach too! Had to be running 10500-11000 RPM Under load.
It sure didn't slow down much when you hit the wood.
That was Impressive. Is that running with .325" full comp chain?

He is likely higher than that. Mine is completely stock running 3/8 chain and it holds anywhere from 10,500-11,500 in the cut under normal circumstances. That's with a 16" bar cutting nearly 16" fresh maple for a reference.

 

[mweba]

He is likely higher than that. Mine is completely stock running 3/8 chain and it holds anywhere from 10,500-11,500 in the cut under normal circumstances. That's with a 16" bar cutting nearly 16" fresh maple for a reference.

Agree. My highly trained ear tach tells me in the mid 12's......although between my cranial refresh rate and allergies that may vary 100r's either way

 

[TK]

Agree. My highly trained ear tach tells me in the mid 12's......although between my cranial refresh rate and allergies that may vary 100r's either way

My ears say its in the "good to impressive" range knocking on "completely awesome"'s door

 

[Tzed250]

My ears say its in the "good to impressive" range knocking on "completely awesome"'s door

Thanks!

While I was running the saw I was looking down at it thinking to myself, "Really?"

 

[blsnelling]

Agree. My highly trained ear tach tells me in the mid 12's......although between my cranial refresh rate and allergies that may vary 100r's either way

I'd go even higher, at least 13K. That baby's screamin'!!!

 

[Tzed250]

I'd go even higher, at least 13K. That baby's screamin'!!!

Thanks Brad!

That's kind of what I was thinking. I have never heard a saw pull anywhere near that kind of revs in the wood.

 

[Tzed250]

OK, so air leak it was. I cut the base back .025 so I could put the base gasket back in. I also cut a relief on the radius between the base and extension. Hopefully I'll get it back together tonight and test it tomorrow.


Base by zweitakt250, on Flickr

 

[mweba]

Nice work! Vid later?

Watch them dang transfer cap screws also.