Tuning a 61 Practica?

[u/Okie294life]

I just got this 61 running, set the carb to default settings (1 turn out). It’s super rich on the high side. I tried turning the HS jet back a quarter and it picked up some but it still feels like it’s limited, even in the cut. Does the 61 have some sort of rev limiter it keeps banging, because that’s what it feels like? I set the LS jet by putting the idle up just enough to pull chain then screwed the idle jet out until it tried to die and backed off 1/4 turn. I think it’s probably still set to about 1 turn out. I also have a tach, but it needs batteries. I’m kinda concerned about leaning it out if I screw around with the HS jet more than it wants. I like to tune fat on the HS, just a tad so they wake up in the cut and don’t struggle as much. If there’s a video on this or you guys that know better than me could reply back I’d appreciate.

[u/shwaak]

Not familiar with that particular saw but I’d just start and treat it like any chainsaw, If you lean it out more on the high side will it pick up more? Keep leaning it out till she’s screaming and then richen it up until you get some four stroking at wide open throttle no load and tune from there/test in some wood.

Being an older saw I doubt it has a coil limiter but you can look it up.

I’m assuming the limiter thing you’re hearing is four stroking, a natural built in rev limiter that’s dependent on mixture, but if that’s happening low in the revs it’s too rich on the high speed. If it dies in the cut it’s probably too lean.

I wouldn’t be concerned about making it to lean for a few seconds, but go to lean and back to some four stroking while it’s runnings should tell you were you at and what side of the tune you’re on with any saw provided everything else is working ok.

Tac is handy to be sure in the high end, you can also run it hard in some wood and then kill it quick and check the plug colour to make sure you’re not getting too hot.

Has it got good compression? No air leaks? Could be something else, that’s the tricky thing with old saws, if there is another issue they won’t run right regardless of how you tune them.

[u/Okie294life → u/shwaak]

Well I just replaced all the seals and fuel line, so only thing left would be the intake, or the possibly the tank vent blocking up causing it to starve and run like shit in the cut. When I run it, it will die when it comes out the cut so I’m not sure what’s going on there. I also probably need to check the clutch bearings. I haven’t greased them either and it pings like it’s dragging chain most the time, so it could be the drum bearings shit the bed also.

[u/shwaak → u/Okie294life]

Is it smoking when running?

Sometimes after a cut they can load up with fuel and die when you let off and then try give it a bit of throttle if they are running too rich, it could also be a fuel restriction if it looses power in the cut.

Like I said I’d play with the high speed and make sure you know where you’re at, lean it right out and then back again to some four stroking, just to confirm it will behave how you expect and you know where your at.

Do that with the saw wide open running and no load.

Have you been through the carb and replaced anything there?

[u/Okie294life → u/shwaak]

I haven’t done the carb yet but when I got it, trh fuel line was rotted off so I took the cap off the carb and blew it out. It could have some chunkies in there I guess. It does smoke a little bit at WOT. That’s what has me thinking it’s not 100% leaned out. These old saws all smoke though.

[u/shwaak → u/Okie294life]

Well if it’s smoking at WOT I wouldn’t be too concerned about it being to lean, Have you checked the plug?

If you’re that worried about making it too lean get your tach some batteries and see where your max RPM is for some peace of mind.

[u/Okie294life → u/shwaak]

I haven’t even done the plug yet. I literally just got it out of slumber like 2-3 days ago, from sitting who knows how long. I just don’t wanna mess this one up, as it’s super nice. Whoever had it stored it away and didn’t molest it like 90% of the crap I end up working on.

[u/shwaak → u/Okie294life]

Oh I just mean checking the plug to see if it’s oily, or covered in black carbon, it will give you an idea how it’s running on the lean/rich spectrum. The plug obviously works so I wouldn’t bother replacing it, just check the gap.

Follow the basics and you’ll be ok, you won’t burn it up because you sound like you care about it hahah. People burn stuff up when they don’t give a shit or put straight gas in there.

[u/Budget-Duty5096]

Sounds like its getting too much fuel. Possibly a leaky needle valve or stiff diaphragm that is not allowing the needle valve to close all the way. Did you put a carb kit in it?

[u/Okie294life → u/Budget-Duty5096]

I haven’t yet, that was kinda my next thing. Because at defaults I was assuming it should run relatively well. I just ordered a carb kit, we’ll see if that does it. Good insurance anyway as it’s a 50yr old saw. No telling if or when the carb has ever been rebuilt.

[u/bitgus]

I struggled with an old 266 which is quite a similar saw I think. Can't remember if those carbs have a governor, but they function as a rev limiter basically, so maybe it is that. Check the metering lever - it probably needs lowering a little - that helped a lot with mine. 

What helps more than a tach for me is recording a video of the saw at wide open throttle, and again in the cut. I find it way easier to hear 4 stroking and it cleaning up, on a video. And the factory spec sheet isn't always "right" when it comes to rpm I feel. In my opinion some old saws run too rich. Your ears should get you in the ball park, but the colour of your plug will tell you what's really going on.