3120 Gone BAD

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blsnelling said:
Thanks for filling us all in Dan. I knew you'd be around shortly to do so. There were several things stacked up against this saw.

1. It was ported, kind of
2. The ignition was advanced
3. It has an unlimited coil
4. It's running the stock 1.12mm jet!!!!!!!!!!! The carb was never fattened up. It was doomed to die.

I found a paper clip that measures 0.044" and it's a tight fit. That's the same as 1.12mm, so I know it had not been drilled. I'm going out today to find a 3/64" drill bit. That's the same as 1.20mm or 0.047" or a #56 drill. I'll give that a whirl and see how it does. With this carb not being adjustable, I've got to jet it a little on the fat side of perfect, since you can fatten it up when it needs it, like a dry cold winter day.
Click to expand...

hmmmm, if only you had a machinist buddy that was coming over later.....

Dang it, spoke too soon. have a 0.052" but no .047"
 
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The saw's running like a dream! I drilled the jet out to .047", which is a 1.20mm jet. It was turning 14,700 there, and actually sounded really good. It was still 4-stroking a little. But I wanted it a little fatter knowing that it will likely run leaner in other conditions, and will likely be use for real work. I then had to use a tiny tappered diamond reamer and took the jet up to .049" or 1.24 mm. That's 22% larger in area and 6 sizes larger than stock. It's now turning 14,300 and 4-stroking solidly, but not too rich.

I don't know what's up with the compression numbers. This heavy beast will just hang on the rope. I've had it snatch the recoil out of my hand too. I think this saw is going to be crazy strong now.

Please excuse the background hum. I had the camera setting on an electrical box.

<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/D9HNFEb9mX0&hl=en&fs=1&"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/D9HNFEb9mX0&hl=en&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>
 
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Nice job Brad :clap: I didn't know those big saws could turn like that.
 
Looks awesome and sounds good too I have my ported 395 set at 13,200 and wondered if that was too much but it four strokes good but I bet that 3120 would flat spank my 395.
 
Nice saw,,, but now that you have opened up the main jet and it is ported it no longer meets the US EPA strict guidelines, so pack her up and send it north, I will send you my addy!!!:hmm3grin2orange::hmm3grin2orange:
 
could those marks on the piston be from getting it very hot and turning it off, and the discoleration it from the piston sitting with the port covered?
 
I hope you like what I've done. I kind of took my liberty to make the saw right. I couldn't stand leaving the port work in the mess it was in, especially on such an expensive saw. Neither one of us had any idea what I was going to find when I looked at this saw. I know I was more than a little surprised.

I didn't have a chance to get it in any wood today. I will do that Monday, and then it'll be on its way back to you.
 

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