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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 29472
Experience:  Service manager and technician for all brands of engines with 40 + years of experience.
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Mountfield 1740h engine runs normally but when elecromagnetic

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Mountfield 1740h engine runs normally but when elecromagnetic clutch is engaged engine backfires and shears the flywheel key
With engine off, can you turn the electric clutch pulley and the deck assembly? The clutch may be locked and is locking up the engine on engagement. ???
Customer: replied 2 years ago.

Dear Sir,

The cutter blades on the deck moves freely and the Clutch moves freely and the micro switch works.

When I depress the "clutch Switch" it immediately backfires and shearers the key

Customer: replied 2 years ago.

Dear Sir,

The cutter blades on the deck moves freely and the Clutch moves freely and the micro switch works.

When I depress the "clutch Switch" it immediately backfires and shearers the key

Unplug the wires from the electric clutch, then turn on switch to see if it does the same. What are you torquing the flywheel bolt to? What is engine model number?
Customer: replied 2 years ago.

.

Briggs and Stratton 1740H

Model : 31G777

Type : 0120E1

Code : 021213ZE

Torque : 60 Ft. Pds

After 10 sheared woodruff keys flywheel has cracked.

Waiting for new flywheel to be delivered from USA

Unable to run test at present

http://outdoorpowerinfo.com/engine_specs/briggs_fly_torque.asp
Torque looks to be 100 ftlbs
How did this all begin?
Customer: replied 2 years ago.

Cutter blades struck a mole hill and sheared the flywheel Key

After many attempts "9" in total ran out of shear pins and a cracked

Flywheel.

Without energising the Clutch the engine would start on the key and run sweetly .On pressing the Clutch switch, Very loud backfire and sheared flywheel key.

On examination each time clutch was not seized and blades free.

Could it be carburation and or governor

I will have to put you on hold until I receive the flywheel before I can run your latest test

Yours Aye,

Jim

I think the problem is you are not putting enough torque on the flywheel bolt/nut, shows to be 100 FT. LBS.!
Key shears as soon as load is put on engine, then it backfires!
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