Just picked up a 22261 lawnboy, question about rpms

Joined
Sep 10, 2018
Messages
228
Location
Northern va
Picked up one with carb issues. Mower is well used but still runs ok. Had a Aftermarket carb on it and surged like crazy, and run poorly overall. I ended up buying a used oem carb.

did some research about replacing the throttle plate, replacing the pilot jet with the bigger Briggs jet and drilling the main jet to a #67 wire gauge.

mower runs much better now with no surging but it feels weak at anything below 3600 rpms. Spec is ~3000. At 3800 it sounds a bit fast, but cuts very well.

am I going to kill it at 3800 rpms? I read the same engine is used in a snowblower and it spins to 4100 rpms.

I’ve been running 32:1 echo red armor and 90 octane e0 gas.
 
There's a CPSC max speed for the blade that you may be exceeding. The engine can take it, unless you hit a rock.

I think you may still have some issues-- I've had weak 4-stroke mowers that I've bumped up the speed as a crutch but this doesn't last long.

I assume you checked that the blade is sharp and the correct one for the mower.
 
I don't know if the engine will fail, but I'm fairly confident it should not be weak at rated RPM. I have the same engine on my mower and the main jet did not need to be enlarged. Only the pilot jet needed it. Mine will easily power through foot tall Florida grass.

I love these mowers. They are powerful and light and a joy to use on irregular terrain.
 
There's a CPSC max speed for the blade that you may be exceeding. The engine can take it, unless you hit a rock.

I think you may still have some issues-- I've had weak 4-stroke mowers that I've bumped up the speed as a crutch but this doesn't last long.

I assume you checked that the blade is sharp and the correct one for the mower.
Yeah the blade was in good shape, but I took it and had it sharpened and balanced.
 
I don't know if the engine will fail, but I'm fairly confident it should not be weak at rated RPM. I have the same engine on my mower and the main jet did not need to be enlarged. Only the pilot jet needed it. Mine will easily power through foot tall Florida grass.

I love these mowers. They are powerful and light and a joy to use on irregular terrain.

I probably should have tried it without enlarging the main jet first. I may have even drilled it a bit bigger than the #67 drill bit. They are so tiny and hard to keep up with.

it ran so poorly before so I don’t really have much to compare it to before and after, but it just doesn’t feel very strong unless the rpms are up there.

it sure is nice to mow with so far. Very light and easy to maneuver!

it 4 strokes lightly at full throttle, no load and cleans up nicely when put into grass
 
Thanks for sending that. While the carb was used, I did take care to only snug up everything that I took apart and retightened.
 
Clean the exhaust port and muffler any carbon build up their will make these engines feel weak. These engines call for ashless oil so get rid of the echo oil and get some outboard or lawn boy oil.
 
When you get your Lawnboy 22261 “dialed in” there should be nothing weak about the power it puts out.

I sold my 22261 to a good home after I moved to a condo. It was the only mower I ever owned, that could cut tall grass OVER the wheel height without stalling. I don’t know how many RPM’s it was turning at the time, however, I fondly remember seeing neighbors peering through their blinds, to see it I was running a mower or a wailing chainsaw. 😂

By the way, I have several leftover pints/quarts of the discontinued Mobil 1 MX2T / 2T 2 cycle oil, if interested (and wish to haggle over the price). PM me. It cut the amount of 2 cycle smoke to next to nothing for me for this mower.
 
Quite a few people have been having good luck curing the surging issues the Duraforce has by adding a second governor spring. As long as the hole in the throttle plate is the larger one, the oversized Briggs jet isn’t needed. But once you get things ironed out, I’d drop the RPMs down to around 3200.

L8R,
Matt
 
Back
Top