Dolmar throwing chains

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redhawk23

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My old Dolmar 421 threw chains and my brand new Makita 4300 is doing it as well so it has nothing to do with worn parts. It happens frequently and involves a minor pinch usually while limbing a downed tree. The chains are not loose, I’ve tightened more than I should and it still throws chains.

I had a chain or two shortened by a link but between using different saws I lost track of determining if that solved the problem, though I think it did and there’s really nothing left to try.

it seems like a design defect in the saw if I can’t use chains off the shelf.

thoughts?
 
I’m pretty sure my current chain came with the saw and I keep a box on hand to avoid mixups. I only buy Oregon 91vxl056 (3/8, .05).
 
I had a couple different bars on the dolmar. I had a couple woodland pros that didn’t change anything and a Oregon with a larger nose that I also threw chains on.
 
I’ve read that the greater the space between the heal of the bar and the sprocket the more “unstable” the chain becomes and the more likely chains will be thrown, thus the reason to shorten the chain.
 
That model did not come from the factory with regular 3/8 pitch drive sprocket. I think you could get it in 3/8 lp and .325. Something to consider.
 
keep the chain tight...it is really as simple as that.

3/8lp is only rated for 3hp and the 421/4300 is 2.9 so there is quite a bit of stretch running those chains and with the tiny lp bars it doesnt take much and you throw the chain.
 
The chain I mentioned is LP and I don’t know what you mean by the saw not coming with a 3/8 sprocket
There are two 3/8 types, one is the full size 3/8 that is common of fairly powerful
saws from 60cc and up, the 3/8 that came on your saw is 3/8 LoPro, they are not the
same, the chain for one should not be used on the other, same with the bars, full size
3/8 nose and the LoPro nose, you need to match up a bar, a drive on the saw and a
chain to match, or you will end up with what you describe happening.

If the oil holes are in the right place, then you need a 3/8 drive sprocket,

if your saw has a rim drive then just change it to a 3/8.
 
They could be bought with either the 3/8 LoPro setup or the .325.
Keep a good eye on the drive links that slide in the bar rail, they can be
bent sideways, that makes them catch in the bar rail, if they catch on the back
heel of the bar as they enter, they will derail, they can also derail on the nose of the bar
when they contact and ride round on the nose sprocket. The chain its self could be bent
side ways, this can happen as a result of the first derail, a pinched bar is also a problem
especially when a bent drive link or a chain that is bent sideways goes through the tight spot.
You could also have a bent bar, that will also cause problems and possible derails.
 
I am currently using the bar and chain the saw came with new and it’s throwing chains.
It could still be bent even from new, they are light, and as far as I remember the 3/8 was
a lighter bar than the .325 version. If you got the bar pinched, then there is a chance the bar
also get a bend, people don't realize how much pressure they can put on a bar when trying to
pull it free, I pull the stopper, and bang in a wedge to open the cut, then the saw falls out.
If you have no wedges, cut a 2 inch piece of branch, and flatten the sides to a point, it can
save the day every time.
 
There is no piece of plastic between the bar and the inner case / clutch
side of the saw is there, that should be removed if there is, it would be over the
bar studs if its still in there.
@fordf150 had a good few yt videos up of that saw with various bars and chains,
in one his chain came off, there was a reason, it was put back on and that was that.
 
How is the clutch drum and bearing? try running it with the cover off and watch for wobble? something is going out of alignment...could even be a bent crank or bad crank bearing.
That's one of my worst fears when buying even a new saw, a misaligned crank,
it would be my luck to get the one in million that the chain loosens and tightens on
as it spins.
EDIT, just re read the OP, this is happening on a new and an older saw, both saws
essentially the same, Makita EA4300 / Dolmar 421
 
That's one of my worst fears when buying even a new saw, a misaligned crank,
it would be my luck to get the one in million that the chain loosens and tightens on
as it spins.
EDIT, just re read the OP, this is happening on a new and an older saw, both saws
essentially the same, Makita EA4300 / Dolmar 421
Chain adjustment issue, I'd happening on 2 saws imo.
 
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