Carb adjustment advice needed please.

[BobbyDee]

I've noticed that on my Echo 620SX that as I increase revs there is a point at which the saw starts to sound a little rough. The engine note is nice and smooth to start with but then I can hear and feel a slight change at a particular point. Advice needed as to whether the mixture might need adjusting and if it does, the best way to go about this. There are 3 adjustment screws...H,L, and T and my assumption would be that L would be the one to go for but before I dive in a possibly end up worse off I was hoping for some tips from those who are more experienced in this area.

[peatff]

That sounds about right if it cleans up when it's cutting. You adjust the L (low) if it's hesitant before picking up revs or if it will not tick over along with the T (tick over) The H (high) circuit needs to be a bit rich at the top end which is the roughness you hear or it will overheat and lean seize eventually.

[BobbyDee]

So the roughness is ok, nothing to worry about?

[peatff]

If it's still running rough under load when you are cutting wood it may be over rich but if it is a new saw leave it till it's had some run time and if it goes for a service it should be sorted then. Use it for a while and don't worry about it. I don't know if the saw also has a rev limiter but it could also be something like that causing it if you are running it but without cutting.

[BobbyDee]

Here's the plug if any help.

[peatff]

It looks a bit dark but it's not fouled and sooted up. Leave it if it's not causing a problem it's better a bit rich than getting it too weak.

[BobbyDee]

Thanks.

[spudulike]

I have noticed this mid range growl, especially on my 346 in its tuned state. Nothing to worry about as long as the saw is not over revving at the top and displaying a bleached or graphite grey plug.

 

You should have tan brown somewhere around the electrode area to be good, black is overly rich!