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Discussion Starter #1
Hi, new user here. some of you addicts would probably be wondering what kind of mower i have. i have a Lawn-Boy 8431, F-Series w/ metal walbro float carb. it works but its broke. LoL. i was cutting the grass and Major power loss. like cutting grass on lower then low power setting (low setting on this thing is still beastly though). i finished cutting my lawn with my other mower though. not as powerful though (yes it is a lawn boy too (i dont know if its really a boy though, i dont know much about it)).

so far with the 8431 i checked the fuel flow, make sure muffler is not clogged (never knew that thing was a muffler.. not efficient). i think a seal could be leaking though. .. <insert suspense for pictures> . and i haven't work on a motor before, so i didn't disassemble it yet.
 

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Welcome. Is there oil running down the crankshaft?
 

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:Welcome1: ....you'll enjoy this site.....the pro's will get you up & running...I'm just a tinkerer......:fing32:
 

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5K Poster!!!
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Welcome aboard!

You need to check the exhaust ports on that thing. Sounds like carbon is obstructing the exhaust ports causing power loss. (one of many troublespots) It will require some tool time. You will need to remove the blade, adapter, and muffler. Heres a quick picture tutorial of how to remove that blade adapter that many people have trouble removing. Remember to whack that sledge pretty hard to "spin" the adapter off. There is no other way to check the exhaust ports other than doing this. Good luck.

Neal





 

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Retired Aug.31 2007
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Welcome to the forum. You are all ready getting good advice.
 

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Discussion Starter #8
i've just reassembled the lawn boy. Indy452 thats a very nice post you got there. i removed that earlier though. but my blade stiffener (squarish thing) was greasy (black stuff) on the side facing the mower. (grn68rt im not sure if its oil. i'm not sure on how a 2stroke works)

i got a new spark plug for it, CJ14 compatible spark plug. and wanted to see if the spark plug was the issue. still the same issue. (but i cleaned the mower quite a bit by now). also when i started it the mower basically ripped the rope from my hand (and broke the handle attached to it).. currently using some electrical tape to keep the edges smooth. is there a setting or a reason why the rope would do that?

oh and this link is great. https://lookup3.toro.com/ttcGateway/acrobat/manuals/lball.html
 

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Castor Freak
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Welcome to the forum! Where in Michigan are you located? If your rope ripped out of you hand, it may be a bad flywheel key.
 

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Discussion Starter #10
i'm in saginaw.

and update on the mower. i'm taking pics in the morning. now it becoming a smoker and surges.
 

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finally.....I good set of pics showing the procedure on removing the adapter plate....much thks for that one!!! I will be trying this procedure on my new lawnboy find, this weekend.
 

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Lawn-Boys and VW's
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:Welcome1: :Welcome1: :Welcome1:
 

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LAWN-BOY-AHOLIC
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1,349 Posts
Blade adapters can be a real pain to remove if they are rusted on or too tight. I have had trouble in the past so now I always use anti-seize on the taper of the adapter and the shaft and threads. Lawn-boy engineers designed this type of blade mounting to center the blade on the shaft and to act as a clutch when striking a solid object. The anti-seize will not allow the adapter to stick as mine falls off duing blade changes. There are torque specs that should be followed so that the system clutches correctly but I'm too lazy to look them up right now. Don't over tighten as the clutch action may save you a bent crank if you strike something. I seldom strike the adapter on my LB's with anything, perfering to use a two jaw puller and apply heat to the adapter only, which usually does the trick but may require you get a new adapter as they bend sometimes. But I don't like to take the chance of damaging a crank shaft or the bearings by stiking the adapter with a hammer. I also mark the end of the crankshaft with a filed line so that I can mount the blade perpendicular to the cylinder line which LB recomends for best cutting power and smoothest running.
 

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lawnboys are great!
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welcome to the gang!!!:trink40:
 

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Lawn-Boys Everywhere
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I wanted to add two more pictures to this thread. After talking to my motor expert over the summer. He suggested that a puller is what he uses. I tried it today and it worked great! This is a Harbor Freight two leg puller. Just another option for this common problem.












Welcome aboard!

You need to check the exhaust ports on that thing. Sounds like carbon is obstructing the exhaust ports causing power loss. (one of many troublespots) It will require some tool time. You will need to remove the blade, adapter, and muffler. Heres a quick picture tutorial of how to remove that blade adapter that many people have trouble removing. Remember to whack that sledge pretty hard to "spin" the adapter off. There is no other way to check the exhaust ports other than doing this. Good luck.

Neal





 

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Welcome! Hopefully the experts here will help you get your running problem sorted out. Glad to have you aboard!!
 

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Happy To Be Here
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Codez, Welcome to the MTF

It sounds like the Lawnboy guys have you on the right track
 
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