3 HP Briggs Help

#1
Hi,

I recently got a 3 HP Briggs motor. I completely dis-assembled the motor and cleaned it all out, except for the flywheel. I put it all back together with a new coil, oil. After a few pulls on the rope it fired up, and ran really well. Now I only had it sitting on my bench and didn't have it clamped down. I stopped it to clamp it down and tried to start it again without any success. I have a good spark from the coil. I even replaced it and tried the one from my push mower. No success.

When trying to start it, it back fires. When I rotate the motor by hand until the magnet is aligned with the coil, the piston is starting to go down. Shouldn't be at top dead center?

I have cleaned the carb and all the passages are clean from what I can see. Gas is getting to the motor.

Any ideas I can try?

pete108
 
#4
The timing can be off if your flywheel slipped. Remove the starter clutch and check if the key is sheared (you'll know it's sheared if the keyway on the flywheel is not aligned with the one on the crank).

If it is sheared, remove the flywheel using the appropiate puller from Briggs . DO NOT, for ANY reason, strike or pry the flywheel with an object. Replace the key with an aluminum one. If you use a steel key you risk damaging the flywheel/crank if it slips again.

Clean everything well, put the flywheel back on and make sure the key is not bottoming out in the keyway. Then put the cup washer and starter cup back and torque it to 75 lb-ft.
 
#6
Use one of these to hold the crankshaft on the PTO side (do not use regular vise grips, they will damage the shaft). http://www.irwin.com/irwin/consumer/jhtml/detail.jhtml?prodId=IrwinProd100328

Then while holding the crank use one of these to remove the starter clutch (the round thing in front of the flywheel) http://www.channellock.com/acb/stores/1/415_-_10_inch_Smooth_Jaw_Tongu_P93C3.cfm

Put bolts in the holes on the starter clutch before removing it or they will collapse.

Remove the flywheel with the puller.

To put the starter clutch back on, use a torque wrench with a socket on the square part of the clutch. Do not forget the cup washer between the clutch and flywheel.
 
Last edited:
#7
I got the flywheel off and it was the key that was sheared. Bought and replaced it. Put the motor back together and started it with the second pull of the cord. After running for a couple minutes I shut it off and started it again. Rev'd the motor a bit and adjusted the idle. No back firer. Then it started to bog down when giving it gas. Removed the flywheel and the key was sheared again. Now I don't know what to do.
 
#8
Did you clean the taper really well before putting the flywheel back? Any dirt or oily residue will make the flywheel slip. Use degreaser for best results. You can also try torquing the starter clutch up to 85 lb-ft.

If it still slips, put a few drops of Loctite 242 of the taper (not 271, because it will be stuck there forever!).
 
Last edited:
#12
The usual technique I hear about is to use lapping compound to make the flywheel and crank taper a perfect surface and fit.
Right! I completely forgot about this trick... Probably the result of too much work and not enough sleep lately :doah:

You should try this before you put any Loctite.
 
Last edited:
Top