B&S 5hp vertical shaft lawnmower engine

Pfmet

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Thank you Scrubcadet. The directions on where to find the numbers was made earlier but finding that other number through me of the track. My bad. And when I make my version of the Grim Reaper I’m considering making it a rider! Gosh this stuff is fun, huh? Back to searching for manuals. Hope you all have some ideas. Let me know when to start digging.
 

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Pfmet

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Another follow up. Wired the throttle open and she will continue to run at too high rpm of course. The governor spring is secure and I don’t see how it could have lost so much tension. Though I wasn’t clear on what the setup looked like from day one, but all looks as it should be to me. For what that’s worth. See the pic. I might start loosening some bolts while I wait to hear more? Maybe the coil for the wood chipper will show up today and I can finish that project up before I start this one.
 

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Pfmet

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I now have B&S service manual 270962 in Books on my iPad. Single cyl. L-head covering the 120000 seriees engine which I’m guessing mine must be. This is the only motor covered by that manual that doesn’t have replaceable valve guides which makes sense for a motor costing $159 with a lawn mower attached. I’m going to disconnect the governor linkage and set up some hillbilly throttle adjustment and try running it and see how the governor crank responds as I manually adjust the engine speed. When I rev her up the shaft will turn to (pull) close the throttle plate. As I back off on RPM it should ease off to allow the spring to reopen the throttle as necessary and thereby bring the revs back up. Or maintain steady RPMs if it were hooked up. Then I will need to figure out why it can’t do that before the motor dies! I’m nervous about the oil slinging though now. I know I heard something odd in the sump a couple times though nothing lately. And the “freewheeling “ with what felt like no compression after the hard stop I first described leave me a little concerned. I wish I could remember how much in ran after the mysterious return to life. I hadn’t used it much since I now had the new self propelled version for the lawn and I use that word loosely but she had a couple short bushwhacking sessions before quitting. I hope all your projects are going well. If anyone needs that manual I’d be happy to upload it to the reference library if there is one and someone tells me how. Best, Peter
 

Pfmet

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I made it easy on myself and simply moved the fixed end of the governor spring to apply sufficient pressure to open the throttle all the way. See pic. The new point lengthened it by 5/8” and I know this is not the way to set no load rpm. My tiny tach is on the way. So with a dribble of gas in the carb the motor stated and ran as it should. The governor spun up and knocked the rpms down by a lot and steadied out.But I can’t get a shot with my optical tach. I thought about putting it up on horses and shootin’ Upwards at the blade but that idea lost appeal quickly.:laughing:. So now I need an explanation for what happened that the governor spring no longer positions the throttle properly when in its correct attachment point. What I have now, even if I set the correct no load rpm and reattach the spring, is obviously not “correct “. I’m not getting it. There’s a lot of talent out there I know. Please chime in. By the way, I got the oil warmed a little and changed it. Ran it through a paint strainer and nothing notable. Sure not a clean bill of health but it’s a start.
 

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cpurvis

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What type of governor does this engine have? Mechanical or "weather vane?"
 

cpurvis

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Mechanical

I recommend that you break it open and fix the governor.

If that isn't in the cards, then you need to install a motorcycle twist grip throttle. Engines which don't have a governor need to have an operator controlled throttle so that you can instantly close the throttle to prevent over-revving the engine. Without some kind of over-rev protection, your engine isn't going to last very long.
 
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