Stihl 026 revving without throttle!

[neilM]

Can anyone help?

 

Our conservation group has two 026 saws with problems, you may have seen my other post!

 

The saw seems to rev to high revs by itself, I have decommissioned it and was hoping someone could suggest a cause.

 

My thinking at the moment is an air leak, possibly in the manifold between the carb and cylinder.

 

Anyone have any thoughts?

 

Many thanks,

 

Neil.

[Rich2484]

Ar leak could stall the saw rather than make it rev too high.

 

Where abouts in the country are you?

[spudulike]

Sorry Rich, an air leak can cause the saw to rev high like when the fuel runs out and the only adjustment that will settle it is over richening the " screw but is in no way a fix.

 

Other things worth checking are that the throttle linkage is loose and not catching.

 

It is unlikely the L screw has changed adjustment but it should be one turn out!

[Rich2484]

Ok. With you now.

 

Just had an 026 on the bench. Not much wrong with it exept for chain running on. They are a powerfull little saw IMO.

[neilM]

We are in Suffolk,

 

I'll check on the linkage, interestingly the last user described the revs like it was running out of fuel!

 

I know no one has been messing with the screws, you cant see the heads for gunk!

 

Thanks

 

Neil.

[Al Smith]

It's most likely an air leak and possibley the carb boot .They have a tendency to tear on the bottom side and they just about need to be removed in order to see .

 

The Stihl design of anti vib system on most models uses an annular buffer which is top left hand side of the handle / air box .Over time undetected they have a tendency to weaken a little bit and over time this additional movement stresses the carb boot .