OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines Quantum 50, worth the effort?

Hi all.
I got a Rover Commando from the tip a while back with a Quantum 50 engine on it. I have just finished going over it, cleaned carby and fuel tank, new plug, replaced missing blades, freed up seized throttle control on motor and repaired bent throttle cable up at the control end. She now starts second pull and revs well but is a little smokey. It seems to have pretty good compression and am just wondering if it is worth while pulling down the engine or not. I intend to keep this one for just mowing in close to the sprinklers and shed walls where the ride on can't get to so I can probably put up with the little bit of smoke. Do you think it worth doing rings and valve seals or just run it till it dies someday? All the rest of the mower is in very good condition, base, wheels, etc.

G'day Trev,

Probably not worth doing anything at this point, as it won't be seeing a lot of use. Unless it fouls spark plugs.

As usual with side valve Briggs engines, there are no valve stem seals as such. A ring set would be somewhere in the $30's, plus gaskets.
Edit: I may have steered you wrong there. Just had a closer look through the IPL for my 12F802 engine, and it appears that it has valve stem seals and replaceable valve guides - which aren't depicted in the illustration, but have reference numbers, and are listed.

I'd suggest just running SAE30 monograde oil, and see if it uses any.

I have a Quantum XTS50 on a Masport, and see the occasional puff of smoke, but it doesn't need topping up between annual oil changes.

Thanks Gadge. Is there a drain plug to change the oil somewhere? Or do I just have to tip it over?

Just tip it spark plug uppermost, and drain the oil from the dipstick/filler tube.

Probably best to run the fuel level right down first, as the tanks on these are prone to splitting along the seam.

There is a square or hex drive socket head drain plug underneath, but using it is a complete PITA, as the blade disc has to be removed. And you need a mower workstand, with some way of holding a catch container in the right place.

It be worth mentioning the on the side valves (L-heads) that a worn a valve guide can be a source of oil smoke. Most techs thinks of bad rings and install a new set to still have a smoker until they check and replace the valve guides.

I have replaced several exhaust valves guides over the last few years. At one time I could get aftermarket guides but source has dried up for me. It does require special tools ie reamers to install new guides. Most time the valve faces and seats just need cleaning up the match the new valve guide path as after guide installation they don't always seal properly until done.