LawnBoy Mower Power Surging


Old 04-20-09, 11:38 PM
RhooD's Avatar
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Join Date: Apr 2009
Location: Metro Detroit
Posts: 3
Question LawnBoy Mower Power Surging

My Lawnboy (model 10323) 6.5hp engine runs slow and fast on high speed. It won't run at a steady rpm. It is sometimes very hard to start.

I have new gas/oil mixture and a good spark plug. I cleaned the exhaust pipe under the mower thinking that it had carboned up but it was fairly clean. The air filter is clean.

If I hold the air vane with my finger as the engine is running I can make the rpms run steady and faster. A local shop told me he thought I had a plugged up or dirty carb problem.

How hard is it to remove and clean the carb on this mower? Any tips or ideas would be appreciated.
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Old 04-21-09, 06:58 PM
Join Date: Mar 2007
Location: Southern Wisconsin
Posts: 354
Lawnboy surge

Your unit has one or two dirty jets. This carb can also be distorted by over tightening the two screws in the air cleaner box. The guys at my shop give the Lawn Boy 2 strokes to me for repair all the time. The carb is fairly easy to remove but watch the plate next to the engine and the gaskets. The carb will drop to get the air vane out from under the housing. You may have to remove the drive belt cover for extra room. Remove the choke and throttle cable from the control arm. Remove the screws from the air box and carb. Carefully remove the air box by weaving the throttle control arm and detaching from the air vane spring on the throttle shaft. Next thoroughly clean the outside of the carb of all dirt, grease and grass. There is a jet for low speed on the side of the upper carb which might be under a label. Remove the jet and take a real fine wire, twist tie wire, and clean the hole in the center. Also spray out with choke cleaner. Next remove the base of the carb by removing the four screws. The main jet is under the screen on the center post. Clean the jet good and you can run a wire through the center hole. Also while you are down this far you might as well replace the needle valve and seat, 92-9697 Toro part number at your Toro/Lawn Boy dealer as these carbs are know for flooding when they are not used and the needle valve tip gets hard. You can vacuum test the needle and seat for proper operation. Blow the jets out good and spray with choke cleaner. Re-assemble. When you reinstall the choke and throttle cable after the carb is back in place, put the control in the choke mode and see that the choke is completely closed when you tight the screw/nut back down. Surging at high speed can be either of the two jets causing. Surging at low idle, is the jet on the side of the carb. Watch your gaskets during re-installing as they can drop down on you. Had someone use silcone sealer on a unit and really did a job on messing it up. A distorted carb will surge all the time, even after you clean the jets good as the carb is only plastic so you might have to get a replacement. The replacement carbs are coming in pieces and have to be assembled when you get them. Good Luck. Have been a carb specialist for 30 years and working on these small engines for over 50 now.
Old 04-21-09, 10:29 PM
RhooD's Avatar
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Join Date: Apr 2009
Location: Metro Detroit
Posts: 3

Thank you so much for the information. I will attempt to do this myself. I am sure that I will run into some more questions, so I may be needing your advice again. It may be a week or two before I get to this project, but I am determined to do this.

The engine surges at all speeds, fast & slow. I didn't say that the 1st time.

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