Mower engine ..reving?

[Unregistered]

Our mowers engine sounds like a dying donkey lol, it started last year and now that this year of cutting has rolled around its time to fix it, the symtoms are
it rev's high then low and black smoke is coming from the , exhaust? it cuts fine but used a whole tank of gas in about 20 mins

Any plan of attack I should begin with, I am not familiar with these small engines yet so not sure.
Thanks
Josiah

[mdshunk]

It may be trouble with the govenor system. On most mowers, the flywheel actually "blows" air across a big "sail" connected to the govenor linkage. When grass and debris get under the flywheel screen and jammed up in the govenor workings, you get really erratic RPMs. Take the top sheet metal covers off the engine and clean out all the grass and such from the flywheen and govenor workings, and see what you get.

[Wgoodrich]

You didn't say what brand name small engine you have each brand name engine has its own unique design. Look under the air filter for high speed fuel adjustment screw. Start the engine without the air filter. This screw should have a spring on it. With the engine running full speed turn that screw in a tiny bit at a time till the engine stops loping. If the engine dies the unscrew the fuel adjustment screw and restart to full speed and then a small bit at a time unscrew the fuel adjustment screw until loping stops.

From what is sounds [high fuel consumption and black smoke] it tells me you are too rich needing that screw to screw in about a 1/4 turn. Try it you might like it.

If you find no fuel adjustment screw chances are you have a tecumse engine with a preset fuel jet. In this case you should find a gas bowl under the carb. Remove the large brass screw and clean out that bowl and the holes in the side of that brass screw. Find the holes in the side of hte screw threads about four of them. Be sure to clean out the bowl.

One of the two methods above should have you getting speeding ticket for mowing your grass too fast with half the fuel usage. Ha Ha.

Good Luck

Wg

[DUNBAR PLUMBER]

When I was younger, I wired the governor on my lawnmower wide open and the motor ran about 6000 rpms. I could of been the poster child for "Don't try this at home, ever."


If I cut grass towards dark, I was the only grass cutter in the neighborhood that had a glow in the dark muffler and the high pitched shrill of the motor was spectator sport for many. Good Times, Good Times. :D


I eventually went to Briggs and Stratton and bought a rebuild kit for the Carb and fixed the loping problem I had, dirt in the needle assembly was part of the problem.



Change the spark plug, and the air filter, always every year.

[Jeff194307]

maybe governor,but carb problem is more likely. Also may have air leak at carb mount. Remove carb, disassemble and soak overnight in vinegar or carb dip. make sure to remove all gaskets and rubber parts prior to soaking. When you take the carb out of the soak, rinse it good with either water or spray choke cleaner. blow dry and check all the little passages. Let me know if the surge goes away.