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Discussion Starter · #1 ·
Last year I bought a used Husqvarna 21" self propelled walk behind with electric start. It could be 5 years old or more, but doesn't appear to have many hours on it. It is in good working order overall. It starts easily and runs good if you use the pull start.
The electric start did not work well when I got it and it seemed like the battery just needed charging. It is a 4 cell Liion 12v and after charging the multimeter said 13.3 volts. However, while it will start the mower when cold (compression is low), after it has run a while and well warmed up, the starter will crank the engine (B&S) only to the compression stroke and then stop. The starter/battery just doesn't have enough umph to crank it when it is warm. I can pull the rope and it will start right up. Once the motor cools, the electric start will crank and start it again.
I tried replacing the LIIon battery with a new sealed 12v lead acid battery and it does exactly the same. I have checked all connections and wiring including the switch and all seems to be in order. I pulled the starter motor and examined it and did not find anything obvious like loose bearings, broken gears, etc. I checked the gap between the flywheel and the magneto (?) and that is correct with no signs of rubbing. I checked the front wheel drive belt and it is loose when not engaged.
I'm not sure if the system ever worked properly. Maybe it was a dud from the gitgo. Anyway, am I missing anything?
Any help or advice appreciated.
 

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Last year I bought a used Husqvarna 21" self propelled walk behind with electric start. It could be 5 years old or more, but doesn't appear to have many hours on it. It is in good working order overall. It starts easily and runs good if you use the pull start.
The electric start did not work well when I got it and it seemed like the battery just needed charging. It is a 4 cell Liion 12v and after charging the multimeter said 13.3 volts. However, while it will start the mower when cold (compression is low), after it has run a while and well warmed up, the starter will crank the engine (B&S) only to the compression stroke and then stop. The starter/battery just doesn't have enough umph to crank it when it is warm. I can pull the rope and it will start right up. Once the motor cools, the electric start will crank and start it again.
I tried replacing the LIIon battery with a new sealed 12v lead acid battery and it does exactly the same. I have checked all connections and wiring including the switch and all seems to be in order. I pulled the starter motor and examined it and did not find anything obvious like loose bearings, broken gears, etc. I checked the gap between the flywheel and the magneto (?) and that is correct with no signs of rubbing. I checked the front wheel drive belt and it is loose when not engaged.
I'm not sure if the system ever worked properly. Maybe it was a dud from the gitgo. Anyway, am I missing anything?
Any help or advice appreciated.
Welcome wilmayo. It could be a weak starter OR the valves might need an adjustment. After some time, the valve lash will widen and then the (ACR) automatic compression release won't function as designed and create too much compression for the starter to overcome. This is a common problem with Briggs & Stratton overhead valve engines and possibly your Husky?
 

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Discussion Starter · #3 ·
Welcome wilmayo. It could be a weak starter OR the valves might need an adjustment. After some time, the valve lash will widen and then the (ACR) automatic compression release won't function as designed and create too much compression for the starter to overcome. This is a common problem with Briggs & Stratton overhead valve engines and possibly your Husky?
An ACR issue seems logical. I'm guessing that it is just a matter of removing the valve cover and adjust with a feeler gauge? Would that alone allow the ACR to do it's thing or would more adjustment be required?
Can you elaborate a bit regarding the "weak starter". What does that mean; how do you diagnose and what is the likely repair?
Or, would you advise taking it to a repair shop and let them sort it all out (I do have some shade tree mechanic experience and tools).
Thanks
 

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Adjusting the valves to correct specs will allow the ACR to work with no other adjustments. Search youtube for valve adjustment procedure. (34) How To Adjust Overhead Valves On A Lawnmower - YouTube

I say weak starter which could be caused by dirty commutator, bad brush's or burnt wires. If it works good on a cold engine, I would guess it is ok and the valves are likely the problem.

Here is a link to the Briggs service manuals on this site.
Common Engine Specs | My Lawnmower Forum

Good luck, let us know the outcome.
 

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Discussion Starter · #6 ·
Success! Both valves were at about .015. I reset them to specs and the electric start now works just fine. Without your help, I would likely have had a hard time making the association between the two and would probably have ended up spending big bucks at the mower shop.
Thanks again for the help.
 
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