OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines B&S 3.5 hp model 91202 Linkage Set Up

hi gents, adjusted the cluth as you mentioned & all seems ok thus far- much appreciated for the assisitance. Hoping you can help with my next one. Have a B&S 3.5 hp model 91202. Runs extremely well except for my governore linkage set up. Originally the engine was surging so I replaced the diaphragm, cleaned carby, fuel tank etc. Have since changed the governor setup (maybe I didnt need to?). Anyway, enginer runs well, but whilst the throttle cable is still the engine will rev highly for 15-20 secs, then will slow down for no apparent reason. I have attached (I hope), 2 pics 629 & 736. 629 was the old set-up & 736 is my new effort. I think possibly both are incorrect?? Hoping you guys can suggest correct governor set-up. Most appreciated for your assistance. See next post for 2 x pics.

rossf,

You need to put the gov spring end in where the throttle cable goes in order for it to work (ref original pic).

The B&S governor on those relatively early engines had an air vane connected by a wire to a pivoted link. The pivoted link was connected by a spring to the speed control. Another wire connected the pivoted link to the throttle butterfly. The force from the air vane was balanced by the force from the speed control spring, so the position of the link moved back and forth depending whether there was more force from the air vane or the speed control spring. The throttle butterfly simply mirrored the position of the pivoted link, since it was connected to it by a rigid wire. What this meant in practical terms was that there was always a rigid wire connecting the throttle butterfly to the governor.
In your original picture the arrangement was approximately correct but the governor spring may have needed to be connected to the hole directly below the speed control cable - most likely it won't make much difference since it is still attached to the same bell crank.
The original problem you described sounds as if the governor may have been hunting. This can be due to something wrong with the governor, but more often it is just lean mixture. Try adjusting the mixture screw a bit less than a quarter turn anticlockwise.

thanks fellas, will try the option you have suggested. Although I will need to buy a new spring I feel, as I had to manipulate the current one a little to make it work. No idea of the B&S part number though (there are so many). I actually tried to replicate the set-up in the attached pic (circled in red)as it looked "logical" but very hard to see all the parts from that diagram & how / where they fit. I get the gist of what you are saying with the air-vane & rigid wire, so fingers crossed. Will let you know- Cheers Ross.