Chainsaw Repair

Put a "new to me" 42" b/c on my 2100 the other day and went to kick some stump butt.
Luckily I also took along my 394xp, because it ended up doing all the work.

The 2100 starts easy, idles fine, runs good at WOT.  I cut into the stump about 6"- 8" and then it started to bog down.
Tried feathering the throttle, but could not find a spot that it would stay running.
I have not used the 2100 since last year on another big stump and work fine as I recall.

It had been run dry last season and put away.
Put brand new gas/oil in that morning.
Felt like it was starving for air or gas or something while in the cut.

What are possible causes?

The 2100 has a governed carb and must be tuning while under load.  So they might sound fine when rev'ed up with no load because all the fuel is coming from the limiter circuit.  Once in the cut and pulled below the limiter circuit RPM it could be running very lean. 

As well, the limiter circuit could be the problem.  Their spring check valve often gets weak and dumps extra fuel at too low of RPM.  The limiter circuit can be disabled by placing an aluminum disk (cut from pop can) under the check valve (the brass screw plug on the right side of the carb next to the choke shaft).

Also it could be a fuel delivery problem.  Plugged fuel filter, crracked fuel line or the carb could need a rebuild.

Good luck!

Least now I know who to call for a 42"     .404 or 3/8?

It is a 3/8 with a full skip chain.

I was unable to get good results with just re-tuning the carb.
Took the carb out and checked the governor.
Looks like someone had already defeated the limiter.
Found a small metal plate under the brass screw.

Will order a rebuild kit for the carb and see if that helps.