Carb Adjustments

I have mentioned that I bought a reconditioned Husky 435. Saw was grossly out of tune when I got it. Have it running pretty well now and have put maybe 8-10 tanks of fuel through it, maybe a bit more.

I had it screaming (it's all relative ) at one point but got nervous it was too lean and I was going to fry it. I've heard this can be a problem so I richened it up for safety sake trying to hear the 4 stroking and figured richer was better at least early on.

Recently I have been leaning it out by an 1/8 of a turn at a time as it was not pulling as hard as I knew it could. Today I checked the plug and took a peek in the cylinder. Plug is chocolaty to a bit dark. Top of the piston is dark. Feel like it should be a little lighter and I can keep leaning it out.

So my question is; is using plug color OK as a guide? I don't have a suitable log to cut cookies from and play and I'm not totally confident my ear is good with the 4 stroking thing anyway. I think it was burbling out of the wood and that I'm real close to optimum now that it's breaking/broken in. Guess I'm just looking for a way to confirm.

 

You want to make one or several cuts for a good period of time then shut down right away and dont extended idle it or anything as WOT plug color is what your after not the plug color after a long idle.

 

Good idea. Just lowered the H side another 1/8. I should pull the plug with chart in hand for a good reference rather than just going by memory. Any thoughts on piston top color/condition?

 

Piston top usually is the same color as the insulator on your plug. Just read the plug.

 

Have the chart or phone in hand.

 

You should be able to tell a difference in the cut sound and a burble out of wood.

 

I really don't have anything on hand at the moment to cut cookies or anything else for that matter and have put up the wood I need to this year to stay on track. I'll have to go find a nice 8-10" log to play with and then try to confirm what my ears and the saw are telling me with the plug.

I can't complain with how it starts, idles and cuts but I'm pretty sure it has a little more.

 

For a guy with no tach and, one that can't hear the 4 stroking, plug reading is all you have, And, it is the best indicator on how the saw is running. Everything else are just indicators of where that plug will read.

I like tach's. they are extremely handy to help someone recognize 4 stroking. Use the tach to get it close but, error on the rich side. Listen to WOT under no load. Then use the tach to get it lean and run it for just long enough to hear what lean sounds like without a load. Then turn it back down to slightly rich and tune it in the wood.

Do this by simply cutting under load and listen to how clean the saw is running. When correct, it should be smooth under a load. It will be at lower rpms due to the bog caused by the cut but, the saw will sound smooth at WOT under load. However, when you release pressure and free it from the work of the cut at WOT, it should be more course sounding. Don't t be confused with decimals and such. When running under load it will be quieter due to running less rpm. When running WOT without a load it will be loud but, burble slightly if correct. By burble, I mean more course. Madison's saw shop has a great video on this process. And You tube videos by many guys has it too. One of them has even posted here in this thread if I'm not mistaken. A tach is useful to teaching you what each state of tune sounds like.

So, Id get the saw HOT, set it slightly rich by the tach, then tune it in the cut and WOT without a load, verify it with the plug, and then tach it once correct. So as to know where to keep it while sawing year round. God Bless

 

I agree, I found having a tach very helpful when I was learning to recognize 4-stroking. At this point my tach is usually sitting in a drawer somewhere when I'm adjusting a carb, but I wouldn't have gotten that comfortable with the process without it.

The problem with relying on plug color is that if you get it too lean, you could easily do some damage before you realize it. The tach and tuning by ear both give real-time feedback, but you can't see the electrodes while the saw is running. I think of plug color as a nice way to double-check or to resolve uncertainty in some diagnostic situations, but not very useful as a primary indicator.

 

I have a tach but I do not use it for tuning. A lot of my saws are modified to one degree or another and so any kind of recommended RPM setting would be invalid. Tuning by ear for the 4 stroke to 2 stroke transition out of and in the wood is the best solution for me. In fact I have trained myself to constantly listen to the saw while using it and on occasion have prevented some scoring because all of a sudden a lean condition occurred.

 

Well thanks to all. I been asking these questions on and off and always learn a little more each time. Mag suggested once before that I get a tach but just never got around to it but I should.

In any case I grabbed some 9" black locust from down the block (you guys would freak to see all the wood going unused in my neighborhood) and played a bit. First I pulled the plug again and cleaned it up. Then ran the saw listening to how it sounded at WOT. To my ear it sounded right. Throttle response is good.

Then cut about 8 cookies and was able to hear the saw in an out of wood. I'm satisfied with how it cuts. Can't really lever on it but it's a small saw so probably just as well to let it rev and pull through the cut on its own. Pulled the plug and color looks closer to what I think is right. Need to run it more but for now I'm happy with it.

 

For safety tune the saw in the cut for the biggest wood u will cut and make sure it 4 strokes when u ease off the load alil. It will 4 stroke in smaller wood without pressure but u will be safe in the big stuff. After u have found that 4 stroke point in the big wood use a tach to check WOT out of the cut for future reference on that particular saw

 

Insulator near the electrode doesn't tell you much by its color, except for the obvious. When carb is properly adjusted, plug is correct heat-range, you're running it properly (hot & hard), the upper insulator will be white to light beige, with cocoa-colored band next to the plug's shell, about 1/16-18". If the insulator is white all the way down, and carb adjustments are correct, plug is too hot. Saw this with PP4218, and went colder. Nothing like having a glow-plug.

Sorry, but a tach is a kludge here. If you can get the 2-4 stroking thing right, you're dead-on and your engine will thank you for it. Going by tach relies on the same phenomenon happening at a given engine speed. May or may not. Good luck with that.

Piston crown color can get weird with strange glop, from some stihl oils, it's reported elsewhere.

 

You are right in theory. But, I'm certain to say that if you take a tach and do as I suggest by teaching yourself what an obvious rich and lean tune sound like in your saw, you won't hurt the saw. More importantly, you will teach yourself what you need to know for the health of your saw.

As stated by me and a few others, putting a tach on a saw to tune it is simply following a broad base parameter. By tuning the saw by sound, you get the results you need.

The saw will tell you what it needs. I have a 385XP that is starting to scream at 12,500 even though the spec sheet says it will max there. It burbles well at 12,200. If I had set the saw to the 12,50o recommendation, that I did before based on my tach and the advertised maximum rpm's, Id be rebuilding it it again next year. Instead, I decided to save my time and money this time around and trust my ears and what my plug said. After breaking that saw in and running about 25 gallons through it now, that saw is a beast. It is transfer ported and muffler moddied and, is still only capable of turning 12,200 comfortably. It will noodle a 30 inch white oak block into quarters in less time it took to type the last three sentences versus losing power because it was scored up. A tach caused that damage to my old top end. I won't let that happen again.

Not arguing, just stating my experience. God Bless

 

I think you misread my post. I did not argue against tuning by ear. On the contrary, I said my tach usually stays in a drawer. I only suggested that plug color isn't all that useful a primary indicator.

 

Do a nasty extreme muffler modd and gut those cans and pull the baffels and cats and you will hear the 4 stroke easy.

 

Yep it makes a big difference.

 

I don't think I misread it. Just pointing out that A plug check only requires the saw reaches operating temps. You just cut it off and remove it to check it. No difference than getting the saw operating temps to check with a tach. One is no more dangerous than the other to a saw, in this regard. And, that a tach is not a reliable tuning tool. God Bless

 

my situation is that when the weather changes so does the tuning of the saw, or when I go to the mountains and cut wood it changes the tuning of the saw, or the last batch of fuel had more ethanol in it then the last batch. So I am not going to pull a plug or whip out my tach in those situations when all I have to do is carry a small screw driver and listen to the saw and then tune it as I am cutting. Takes a lot less time when out in the woods.