Husqvarna 61 with 220 psi compression

[JohnT34]

Hi to everyone on the forum
This is my second post and as per the title I am concerned about the compression level my husqvarna 61 has. First off I rebuilt this saw totally from the bottom up. It has a gilardoni 48mm open port piston and cylinder with a new OEM ring. Essentially when rebuilding it I measured the squish at 0.043 and removed the base gasket cleaned up the exhaust and sealed it with dirko finished off the saw with carb rebuild (tillotson 163) etc. Put on a 20 inch bar and chain on it and ran 1 tank of petrol through it and was blown away by the torque and power as the saw was pretty boring before hand. Tonight I decided to measure the compression on the saw and it had 220 psi compression on my guage not sure if this was the max but I could not turn it over further than this point as I was afraid I would break the recoil. I have not rechecked the squish. Also the crankcase for this saw is off a 266xp if that has any relevance
So after all the long-winded description my question to the forum is will this saw blow up or can the components take this sort of pressure?
Thanks John

 

[Canyon Angler]

Sorry, I can't answer your questions, but I just gotta say "HOLY COW, LET 'ER EAT!"

With 220 psi, that's gotta be an ANIMAL! Got avgas?

 

[smokey7]

I have several saws in this series with 195 to 225 and they have ran atleast 30 cords each. I see no problem as long as you oil the bottom eng good with a rich ratio. I run 32:1 mostly with citgo/mystic sea and snow a fd certified synthetic oil. I dont prefer to run anymore then 180-190 but some of them ended up higher then targeted by consequence of machine work. If i ever went back in i would angle the band a bit near the center to lower the comp some. After my rambling take what you want but i see no issue with 220 since a healthy one from the factory was likely 185 190. So you are not that much over stock to be dangerous to the saw.

 

[Canyon Angler]

i see no issue with 220 since a healthy one from the factory was likely 185 190. So you are not that much over stock to be dangerous to the saw.

Interesting, didn't realize chainsaws had that high of compression. Most I ever saw was 175 psi in my old 69 Pontiac 400 (10.75-to-1)...if my memory is right...

 

[smokey7]

4 stroke is way different then 2 stroke. Chainsaws usually have a much shorter stroke then bore diameter. So for instance a 61 and all of its varients used 32or34mm stroke if i recall and a bore from 48mm to 52mm. That short of a stroke allows low octane reg gas and high compression with no issue of detonation. Unlike a pwc engine blowing 185 on premium pump gas mixed with 25% 110 turbo blue jetted sharp with a very good pipe/impeller/pump combo is right on the edge of deto. If my gas is a little old or im at a lower elevation i better fatten it up or ill burn it down.

 

[JohnT34]

Here are some pics of the saw for
interest
The gauge is leaking a bit so by the time I had the phone out of my pocket it had dropped back to 200
I have it tuned to 12000 rpm free on the H screw and have 40:1 synthetic husqvarna oil in the mix
I will throw up a video tonight if I can


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