I have been given a masport with a 4 stroke briggs and stratton - model number 98902. Mower had been stored incorrectly and had oil coming out through muffler. Went to local mower shop and purchased new oil, air filter and spark plug. Drained mower of all oil, had muffler off as well to drain exhaust. Cleaned muffler with some petrol, installed new air filter, installed new oil, new petrol and after a number of pulls and primes got mower running. Mower now starts easy but when throttle is pushed on the mower is revving up and down (Other terms may be surging or hunting.) I took the air filter off and the flywheel cover to observe what was happing - there is a plastic vane that regulates the governor (? I guess). This appears to be going in and out which is affecting the revs. It appears the carby could be running rich as the exhaust smells like petrol (Not just the fact that I cleaned it with petrol) and the governor may be trying to counter the rich mix? I'm only guessing as 4 strokes are a new kettle of fish to me. There was a period before the fuel tank ran dry that the mower ran really smooth, but upon refilling back to surging problem. Any ideas? Also does the air filter foam need to be soaked in oil before using? I thought I read this somewhere but not sure if it applies to this model? I have uploaded a video so you can here and see the problem.
Cheers Mark
Last edited by Bruce; 12/08/1704:02 PM. Reason: Corrected Youtube
