Small Engine Experts

[Ron H]

I have a 26HP B&S engine on my zero-turn mower. Mowing the other day I heard a distinct change in the motor sound and more vibration, came on suddenly. I checked the deck, belt, pulleys, blades – all look good. More tripping found that the sound & vibration has squat to do with the deck/blades. Motor just sounds crappy at idle and throttling it up. Starts fine, no popping, missing (far as I can tell) and no knocking. I go through it every spring clean/gap plugs, oil/filter change, air and fuel filter, grease and lube. Took engine cover off as I hadn’t done this in a couple years (yep should have – lots of crap accumulated). Cleaned all that out. Checked the motor mounts thinking vibration there, nope, they’re tight. The PTO clutch was all of 4-thou out so readjusted it FSM specs. Has around 500 hours on it. Carb has never been serviced so thinking maybe it needs it; maybe skanked o-rings by now. Vibration though just doesn’t resemble a carb issue; not sure.

Anyone have encounters with this…ideas? Thanks!

 

[LowBikeMike]

Yes, balls in internal govenor/balancer fell out. Heavy vibration as throttled up but would run fine. Lesser vibration at idle but very noticable.

 

[Ron H]

Yes, balls in internal govenor/balancer fell out. Heavy vibration as throttled up but would run fine. Lesser vibration at idle but very noticable.

Appreciate the reply. Yeah - those flyweights on the gear can go skank and if they do, cause some other ills as they could snag in the cam gearing. Sheeit, if this is the problem, not a major fix BUT I'm currently in a state of fix recovering from bi-lateral CTS surgeries. What a bee-itch having the hand strength I had when I was 5..

 

[Dave P]

Quick, easy and free....start it up and while running a lower rpm pull each plug wire and see if both cylinders react about equally. With out knowing specific model and type numbers a couple general things....some have two barrel carbs and a partially plugged jet will lean out one cylinder?? Some have a diode in the coil wiring harness that can cause some odd ignition issues. Some sound and run real well on one cylinder after having
a valve guide shift in the cylinder head and take out a push rod.
First check is to see if both cylinders are home and working

 

[mpgmike]

I had an exhaust valve seat drop on our John Deere 165! Pulled the head, popped it back in, then staked it around the perimeter. Been fine for 3 years now. Not only did it have that vibration, but it would back fire through the exhaust when I shut it off.