Hey Dave Propnut,
After looking at the Fource owners manual (PDF) I notice that the bore of the 40cc is identical to the 34cc Briggs.
Hmmm - now if the piston is identical, we may be able to 'upgrade' our 34cc Briggs engines to 40cc by swapping out
just the crank and conrod.
Can anyone confirm.
Manuals for the Weed Boss Briggs engine can be found here -->
http://www.atlanticpowerinc.com/weedboss.htm
There's no replacement for displacement
Ian H