I’m going to check my drive sprocket this weekend and see what it looks like. I swore I wasn’t overtightening but maybe I was. I read the manual and watched a bunch of videos on tightening and thought I was doing it right. The husky 445 only has one bar nut whereas almost all other chainsaws have 2, so I thought by only having one bar nut, maybe it wasn’t able to keep the bar (and thus chain) tight.
I have a 445, so I can tell you it’s not a characteristic of the saw to lose chains like that. A couple of thoughts in addition to inspecting the drive sprocket for wear.
1. Inspect the bar. Pay special attention to the area at the top of the bar where the chain comes off of the drive sprocket right where it enters the groove that runs down the middle of the bar. Look at this area both with a chain still on, just after you remove the side cover and then again with the chain off and the bar removed. This “entry area” can become worn or it can be damaged by a chain slipping off.
Also, inspect the nose of the bar. If there is a burr you can feel or the nose radius is visibly worn, the bar must be replaced.
Look at the groove in the bar. The groove should be an even width the whole length of the bar. If there are “wide spots” in the groove when viewed from above, it’s worn.
BTW, you should be flipping your bar over every time you change your chain. This makes for even wear on both sides of the bar and therefore you get more life out of your bar. A lot of people don’t know this, several people have pointed out to me that “my bar is on upside down”.
2. When tensioning the chain, the tension must be set with the bar nuts on just a little tighter than finger tight AND the bar needs to be lifted upward during the tensioning process. If you don’t lift the bar upward while tensioning and tightening the bar nut(s), the chain will slack as soon as the saw is started.
3. I tension the chain and test it like this. After setting the tension, I pull upward on the chain allowing it to bow under the weight of the saw. I’m doing this in the middle of the bar, BTW. So to me, the right tension is such that I can pull the chain upward off the bar and I can see about 3/4 of the height of the drive link (the “tooth” that runs in the bar groove). If I can pull the chain such that the drive link is totally out of the bar, it’s too loose. If lifting the chain doesn’t expose the drive link at al all, IMO that’s too tight.
Also, IMO, the chain is too tight if I can’t pinch it with my fingers and slide it easily down the bar.
