Another chainsaw dyno...

[J.Noss]

Has there been a comparison of immediately after porting and then after that 10 tank or so break-in. I keep hearing that these are held back a bit in software. But IDK, trying to get more informed.

I recall that with the 592-585xp he did do a dyno compare of the new vs broken-in engine as part of the dyno test and indeed did show some difference between the two, I do think there's some type of break-in mode built into the autotune because after a certain number of tanks they do feel like they wake up like a limiter has been removed.. I experienced that with my 550xp around as you say the 10 tank/1 gal mark before I sent it off to be ported and to be honest it just makes sense that such a break-in mode would be part of the software to improve longevity of the engine.

 

[farminkarman]

Open port Husky 55 and a 372 clone. I am nothing short of shocked on the 55.

 

[Maintenance Chief]

Open port Husky 55 and a 372 clone. I am nothing short of shocked on the 55.

View attachment 401451View attachment 401452

Do anything special to them?

 

[farminkarman]

Do anything special to them?

Well, this was the first one I ever touched. The carb, intake port, and exhaust ports are all tiny, so I would have been happy with anything over 4. I only cut 0.030" from the squish because the chamber looked pretty small. I raised the exhaust back up to 103 because I couldn't widen it much at all. I opened the exhaust side of the transfers at 121 and tapered to 124 on the intake side. After machine work the intake landed at 72... I lowered it to 76 and raised the roof about 1mm and widened the intake about 1mm on each side. My compression tester sucks and I don't trust it, but I would say the saw ended up with about 200 psi compression with only taking 0.030" from the band.

 

[Maintenance Chief]

Well, this was the first one I ever touched. The carb, intake port, and exhaust ports are all tiny, so I would have been happy with anything over 4. I only cut 0.030" from the squish because the chamber looked pretty small. I raised the exhaust back up to 103 because I couldn't widen it much at all. I opened the exhaust side of the transfers at 121 and tapered to 124 on the intake side. After machine work the intake landed at 72... I lowered it to 76 and raised the roof about 1mm and widened the intake about 1mm on each side. My compression tester sucks and I don't trust it, but I would say the saw ended up with about 200 psi compression with only taking 0.030" from the band.

Nice, I build a 55 with an 028 pop up piston earlier this year. It runs like a good 55, which I'm glad about.

 

[farminkarman]

Nice, I build a 55 with an 028 pop up piston earlier this year. It runs like a good 55, which I'm glad about.

Glad to hear it turned out well. The pop-up on the 028 super piston goes against what I try to do with my porting. I much prefer a flat-top piston.

 

[smokey7]

My 55 runs almost as much speed but less torque then my 630. All I got newer to compairvto but 4.5 or 5 feels right

 

[farminkarman]

My 55 runs almost as much speed but less torque then my 630. All I got newer to compairvto but 4.5 or 5 feels right

Are they both modified? According to Acres, both the Husky 55 and Jred 630 were advertised at less than 3.5hp in stock form. The 630 would be more torquey being 62cc and rated at 3.1hp. The 55 is 53cc and rated at 3.3hp.

 

[J.Noss]

Husqvarna 592xp ported courtesy of Joe at HMWF LLC