1974 Johnson 25 hp throttle cam

[jclark00]

When attempting to pull start this motor the mag plat / armature plate where the throttle cam is mounted to travels past the cam follower on the carburetor...this causes the carb follower to cut stuck on the back side of the throttle cam. Motor has not ran yet, it acts like its going to for a few seconds but then dies. The problem described doesn't occur with each pull, but can be repeated every time when a vigorous attempt is made to pull start it Motor model is 25R74M

 

[Crosbyman]

tiller throttle gears or mag plate cam may need adjustments
normally carb throttle plate should just begin to open with the tiller grip at START

 

[F_R]

Two things: First, I suspect the shift/throttle interlock on the starboard side of the powerhead is not doing its job. Second, I suspect the driver coil is dragging on the flywheel magnets.

 

[jclark00]

Thanks for the input Crosbyman and Supreme Mariner... The tiller gears are in good shape, cleaned and working smooth. When twisting the grip throttle the cam follower rides smooth all along the throttle cam all the way to WOT. I do see that a couple of the gear teeth on the bottom of the control arm (starboard side) have a couple teeth that are jacked up.... Supreme Mariner, is this what you are referring to as the shift/throttle interlock? OR are you referring to the "Link and Stop" piece, part number 0581441. I also think the flywheel is rubbing on something...dragging the armature plate too much. I plan on pulling the flywheel tomorrow.. Thanks again for your help

 

[F_R]

The shift shift interlock I mentioned is 317757 (item #42) It pivots in and out at the top end, according to gearshift position. As it does so, the "link and stop" bangs up against it according to gearshift position, thus limiting armature plate rotation. Because of the limitation, the cam should not be able to go past the cam follower.

A common fault is the 316603 > 325542 bushing (s) (item # 44 at the center pivot of the interlock may be missing or worn out. OR the roller bushing 317758 > 323493 may be missing off the gearshift handle. Or both.