Husqvarna 140 x-torq

[olivertye]

I have a Husqvarna 140 x-torq which I'm currently repairing.  Initially the saw would not start so I cleaned the carb and it now starts and idles perfectly.  The problem is that it will not rev up fully.

The carb on this saw looks a little different to what I seen before.  It has two bores, one above the other.  The bottom bore is like a standard venturi for fuel/air intake and has a choke plate and a throttle plate.  The upper bore is purely for air - as far as I can see, and has a third plate for metering air flow.

When the throttle is first activated, the carb is operated as standard with the throttle plate opening.  When the throttle is activated to around 50%, and external linkage on the carb begins to open the plate in the upper bore.

At the point where the plate in the upper bore begins to open, allowing more air into the engine, the engine bogs down.  This suggests that there is a lack of fuel.

I have discovered that by turning out the H needle by almost one full turn (from the position it was in when I received the saw)  that the saw revs up perfectly.

As far as I know, the carb has not been adjusted previously and should be at factory settings.  It seems very  odd that the H needle needed to be turned out as far as it did to get the saw to rev up properly.

Ideally, I would like to get hold of a service manual for this saw or any other literature which gives the correct basic setting for the carb.  In the absence of sourcing a service manual, is there anyone out there who can shed any light on the issue that I've described.

 

 

 

 

[openspaceman]

5 hours ago, olivertye said:

I have a Husqvarna 140 x-torq which I'm currently repairing.  Initially the saw would not start so I cleaned the carb and it now starts and idles perfectly.  The problem is that it will not rev up fully.

The carb on this saw looks a little different to what I seen before.  It has two bores, one above the other.  The bottom bore is like a standard venturi for fuel/air intake and has a choke plate and a throttle plate.  The upper bore is purely for air - as far as I can see, and has a third plate for metering air flow.

When the throttle is first activated, the carb is operated as standard with the throttle plate opening.  When the throttle is activated to around 50%, and external linkage on the carb begins to open the plate in the upper bore.

At the point where the plate in the upper bore begins to open, allowing more air into the engine, the engine bogs down.  This suggests that there is a lack of fuel.

I have discovered that by turning out the H needle by almost one full turn (from the position it was in when I received the saw)  that the saw revs up perfectly.

As far as I know, the carb has not been adjusted previously and should be at factory settings.  It seems very  odd that the H needle needed to be turned out as far as it did to get the saw to rev up properly.

Ideally, I would like to get hold of a service manual for this saw or any other literature which gives the correct basic setting for the carb.  In the absence of sourcing a service manual, is there anyone out there who can shed any light on the issue that I've described.

 

 

 

 

I'm not familiar with this saw but from your description it's a stratified charge engine. The  bottom bore carries a fuel air mix into the crankcase and the top one allows just air into fill the transfer ports as the piston reaches the top of its stroke. Then during the power stroke the transfer port first purges the combustion chamber with the air , to sweep out the combustion products, before the fuel air mix enters. This reduces pollution and fuel consumption by not venting unburnt fuel directly from the transfer port to the exhaust.