[Zak the Rabbit]

im trying to repair my lawn mower, which has a briggs and stratton petrol engine. Apart from the governor springs being shot, there is a big problem - oil fouling :cry:

it looks like at some point i have over filled the oil, and the cylinder and everything is fouled. Ive flushed the carburettor out, drained and properly refilled the oil, and 'cleaned' the spark plug using carb cleaner solvent. Ive then run the machine for a while to burn of the oil (now hardly any smoke, and what there is i thing is from external oil burning off) but it is still very poor firing.

Im guessing i will need to replace the spark plug, but would appreciate any advice from our resident single cylinder petrol heads

[Gwiz]

I wonder how old your engine is? it could be that you have points that need adjusting/replacing/ redressing, if the engine is a little on the "old" side.
failing that, another common problem ocurs when you run the mower out of petrol whilst using it. Very often, no matter how carefull (or not as the case maybe), when you refill the petrol tank, small bits of dirt/grass, falls into the petrol tank on the machine. under normal usage, these little bits of "rubbish" will sit in the tank without causing too many problems. When you run the mower untill you use all the petrol in the tank, these little bits of odds n ends will get sucked down into the carb and into the "jets". this will make the engine run rough, or will prevent it from running at all. The only solution is to remove the carb and the petrol tank, strip them and clean them out fully.
if you think this might be the problem, let us know what type of briggs engine you have, how old the machine is (or what mower your engine is attatched to- that'll give us a rough idear of what engine you have)
if you need any advice regarding stripping down the bits, just sing out, there's a few of us in here that are addicted to the fumes from petrol!!!

[dorimower]

Hello,
 
As Graham notes it would be interesting to learn the mower brand/type.

It may be worth noting that as well as over filling with oil another way in which oil can get into the cylinder is when a machine is tipped on its side (or forward)...thinking particularly of rotary mowers here...most B&S types if tipped will spill oil internally into breather case/breather pipe, into carb, into air filter, through valves into exhaust and above cylinder leading to Red Arrows type smoke effects on the next running 'til it all clears....also some types if tipped another way can spill petrol internally leading to petrol contamination/thinning of oil...and things don't get lubricated..and quickly go poorly :shock:

 Types with a foam air filter can thus have the foam get totally saturated with oil..which can easily be cleaned and lightly oiled to correct....whilst the more recent and slighter higher spec engines have a dry paper air filter which if oil/petrol soaked can't be re-used and needs new replacement air filter...a blocked/contaminated air filter espcecially of the paper type will cause rough running.

Most smaller B&S engines these days take a Champion RJ19LM or J19LM spark plug.

"Dori"

[Zak the Rabbit]

cheer fellas

i drained the oil, mostly from the drain plug but a good bit came out the filling hole onto the step while i had the beast on its side (cant remember why i did that)

refilled to proper level, carburetter, cyclinder and piston head cleaned with carb cleaner, engine run for a bit without exhaust on to burn off the excess oil, then plug soaked and cleaned in carb cleaner with a paint brush. Magneto refitted (put on too close to flywheel, nearly ripped me hand off trying to start it when the magnets caught! :roll: )

now running smooth, quiet and clean. Also put blade back on on its sharp side.

Its amasing how much you learn about engines fixing a mower