[quote=jackg]
I am looking at grabbing a new muffler: will this help at all with vibrations? I checked the air filter and it is good- there is a lot of crap around the carb, etc.
Basically I know nothing about this machine and would like to give the engine a service before I use it much more. I note it has two oil plugs- there is oil in there but after a few uses it has gone down a bit. What oil am I supposed to use and how can I change over the old oil? Is it different oil for each hole? I know nothing... [end quote]
jackg, the muffler has no connection with smooth running or mechanical vibration unless it is blocked up (usually, either by a wasp nest or accumulated carbon).
The two oil plugs are just because those horizontal crankshaft engines are used in a variety of applications, and Briggs may choose to sell them with a "universal" timing cover that has both the front and rear oil filler plugs rather than just one or the other. The correct oil is 30 weight, to an automotive specification (perhaps SG - there are several of them of different ages). If you use a standard automotive oil (such as 10W30) the mower may burn more oil than you would wish, and might even carbon up its muffler eventually, causing it to run poorly. To change the oil you remove the drain plug, which is a square-headed metal plug sticking out from the front edge of the engine's base, above the mower's reel. Before draining, warm the oil by running the mower (preferably, mowing the lawn, but otherwise just run it at moderate speed for something like 10 minutes). Don't forget to put the drain plug back in, then put the mower on level ground and fill it with oil through either the front or back filler plug, as far as the top of the thread (in other words, put in as much oil as you can before it runs back out).
Is the smoke you have seen blue or black? Blue smoke is oil smoke, black smoke is petrol smoke. The two colours have entirely different causes. Either one can be fixed, though.
And please post that long string of numbers from the air cowl.
