Tuning a G660 for milling?s

[EbS-P]

Hi Everyone,

Yesterday I got my tac out of the package it’s been in for many months and finally checked my 2 year old G660 that I primarily use for milling. It was almost 90 out and and it was running 12800 rpm. I have not touched the carb since it arrived.

I have probably 30-40 tanks though the saw and it’s been running well. Broke it in with 25:1 oil and and now running 37:1. I richend it up some — 11.8k rpm and noticed that my power band was noticeably more narrow and I had to really pay close attention to not stall it out in a 28” cut.

Would you leave it richer or lean it back out to 12.8 rpm? It’s wearing my 52” bar now. Would you tune it pulling 156 DL on the big bar or tune it on my 28”? My cuts now are 11’ long and take almost 2 full tanks to finish.

thanks for your feed back

Evan

 

[huskihl]

I would tune it so it barely cleans up in the cut. On a normal milling pass, let up a little bit and it should 4 stroke

 

[EbS-P]

I would tune it so it barely cleans up in the cut. On a normal milling pass, let up a little bit and it should 4 stroke

Thanks. That’s right about where I backed it off to. I can see now running them a bit on the rich side why you want 100+ cc saw for big cuts or harder wood. It would be interesting to see the power curve for carb settings and exhaust gas temps.

Evan

 

[huskihl]

Could run a tank through it and see what the plug looks like. There’s no sense in having it so rich that the plug is running black

 

[kneedeepinsaws]

Could run a tank through it and see what the plug looks like. There’s no sense in having it so rich that the plug is running black

I agree this also causes carbon build up and the last thing you want is for a chunk to come off and score the cylinder.

 

[EbS-P]

Could run a tank through it and see what the plug looks like. There’s no sense in having it so rich that the plug is running black

Good idea. Got to a good stopping point today will pull the plug tomorrow.

 

[drf256]

That’s a lot of bar for a 92cc saw for sure. It’s incredible how much power one needs to mill, I didn’t believe it till I tried.

Definitely tune it for the bar you are using. Like Kev said above, back it out for a second and listen for 4 stroking, it’s the safest way to know.

I’d go back to 25:1 on that saw for milling. 32:1 minimum I’d venture to say. I’d also run it so that it just cleans up in the cut under the pressure you are using. A blubbering saw makes no sense at all, but too lean will lack power and burn up your saw. I’m actually quite surprised that you have a narrower power band at a fatter tune, I usually have experienced just the opposite.

Milling is just a different animal altogether. Is your muffler modded?

I have a 3120 I mill with now. When it was stock and limited below 10k it was fat and cleaned up in the cut. After @Moparmyway had his way with it and I added a @Mastermind adjustable H carb and a 272 coil, it still cleans up in the cut but it’s set at 12500 and wants some more.

My point here is that milling is just different. The extreme heat it causes in the engine will cause it to 4 stroke out of a cut and clean up in a cut over a much broader range. Your best bet is running a tach on it and tuning it for highest rpm ‘in the cut’ and then confirming that it is 4 stroking when it’s out of the cut. Contrary to what people think, the fastest cut speed under load is usually a safe tune, you need fuel to make power.

Sorry for the long winded response.

 

[Moparmyway]

My point here is that milling is just different. The extreme heat it causes in the engine will cause it to 4 stroke out of a cut and clean up in a cut over a much broader range. Your best bet is running a tach on it and tuning it for highest rpm ‘in the cut’ and then confirming that it is 4 stroking when it’s out of the cut. Contrary to what people think, the fastest cut speed under load is usually a safe tune, you need fuel to make power.

THIS !!!!!!

 

[EbS-P]

I’m actually quite surprised that you have a narrower power band at a fatter tune, I usually have experienced just the opposite.

I think it was more to do with the chain. I sharpened after the first slab, this was the first cut after the first sharpening to re-profile chain to 10 degrees. I sharpened after this cut adding a little more hook and it was less grabby so it didn’t stall and I could back off when RPMs dropped.

That’s a lot of bar for a 92cc saw for sure.

Yes it is. My 36” Holtzforma hard nose bar runs too hot, I probably cooked it once, had to redrill tensioner hole after grinding the the nose back flat, only has one chain and it wasn’t on the mill. It’s maxed out at about 29” width. I only get away with it because it’s soft poplar with super soft sap wood.
Evan

 

[EbS-P]

Could run a tank through it and see what the plug looks like. There’s no sense in having it so rich that the plug is running black

More oily/carbon than last time I pulled it out. This is after 6 full tanks.

 

[EbS-P]

Your best bet is running a tach on it and tuning it for highest rpm ‘in the cut’ and then confirming that it is 4 stroking when it’s out of the cut.

I’ll give this a shot. And compare no load rpm to where I set it and where FT had it set. And then when I swap chains I’ll see what difference that makes.

 

[SpaceBus]

I would tune it so it barely cleans up in the cut. On a normal milling pass, let up a little bit and it should 4 stroke

This is how my 395 is tuned after getting advice here.

 

[huskyhank]

Plug looks good.

 

[FergusonTO35]

G660, that is a Redmax isn't it?

 

[EbS-P]

G660, that is a Redmax isn't it?

FarmeTec Holtzforma brand. Chinese clone of the MS660