OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers Scott Bonnar 45 carby trouble

I've got a B&S engine with a horizontal carby that will only run at full revs for about 20secs. The butterfly (pictured) isn't connected to the rod but any configuration I've tried makes no difference. It runs at full revs but the throttle is at 0% which is odd.
The parts diagrams I've looked up give me no help as the are exploded view.
Any ideas? Thanks

Carby pic

Hi Ben,

That rod is attached to the Governor and without it correctly positioned you'll never get it to run right. I'll get back to you showing where it's meant to go.

Cheers,
B.

Unless the OP can find another carb to use or to strip he in trouble as the cast throttle is broken. And for this older slide choke carb new parts are not available nor is the carb. No separate throttle plate used. See circled area.

Of course if someone can weld a new tab on the throttle then it might work.

Cast throttles are removed by backing off the idle speed adjustment screw until the throttle clears the retaining lug on the carburetor body which in this case is already removed.

Hi Ben and AVB,

You beat me to it as I was going to post a photo of how its meant to be attached to the throttle butterfly fitting which is broken and can be clearly seen in the close up photo that Ben provided.

Best to keep a look out on the Classified Ad sites for a spare Briggs Engine (Good or Bad) to source the carby from. Cheaper to buy a whole Second Hand Engine than a carby on its own.

Cheers,
BB.

Ok thanks very much guys. I was thinking about throwing a new B&S on it at some stage and I guess that's made my mind up! Is there a thread about ideal motor size for the 45's? I've got 2 45's at the moment and want to make sure it's not under or over powered.
Thanks very much

Hi Ben,

Most of the engines on the market at the moment should be OK. The current Briggs will work ok along with the Chonda's that are out there at a very competitive price. Don't get anything over the 5 HP mark as it will be overkill.

The only thing to wtch out for now is the PTO shaft size, many of them are 19mm and with that you'll require a 3/4 bore size clutch half as the one you currently have will be a 5/8 unit.

Cheers,
BB.