G'day Norm,
As Bigted says, the horizontal spring is the governor spring. So it will only have tension on it at or past the full throttle setting.

Here's pic from the Service Manual of the layout.
[Linked Image]

If the shop monkeys have fitted a heavier spring, it is likely to rev too high. Factory spec is 3400 +/- 150 rpm.

Do you know if the mower shop had the crankcase apart? If not, it should be fairly easy to fix with a new correct spring and some adjustment.

A short version service manual can be downloaded from http://www.honda-engines-eu.com/web/eec-public-site/shop-manuals
It does cover governor setup and adjustment.

Cheers,
Gadge

"ODK Mods can explain it to you, but they can't understand it for you..."

"Crazy can be medicated, ignorance can be educated - but there is no cure for stupid..."