25 hp screaming hi rpm in idle poss

[american angler]

hello all

i have a 1974 evinrude 25 hp tiller 2 stroke. had it out on the lake and it seemed to run great. i had allways idled down to the start poss at the end of my move, then after a few restarts the motor started at full rpm

screaming hi rpm's, i tryed moving the tiller handle with no change what so ever i had to take the cover off ( in a hurry ) grab my oar and pull the spark plug wires off ( yes theres no kill switch ) i will be adding a kill switch

when u turn the tiller handle and that plate under the flywheel moves does that have a internal return spring ?? that may have broke and mabey that plate is getting stuck in the wide open poss ??

i was able to push the plate back and get the motor started at idle but was afraid to go over half throttle for fear it would do it again which it did do again at start up in nuteral .

any help would be great

AA

 

[Joe Reeves]

Re: 25 hp screaming hi rpm in idle poss

Engine not running. Spin prop and put into forward gear. Twist tiller handle and observe the plate under the flywheel (armature plate, points, cond, etc).

The top clip of the vertical arm may have come disconnected from the plate or the nylon pin at the bottom of it may have sheared.

Strange though, centrifugal force of the spinning flywheel coupled with its magnetic field should have forced that plate back to its idle position.

Let us know what you find.

 

[G DANE]

Re: 25 hp screaming hi rpm in idle poss

Once my brother in law did this to my 1973 25 HP when we were out fishing. What he astually did was stopping motor while it was in forward gear, by kill switch. Then afterwards forced it into neutral, to start it. Then it went off like a rocket !!!. This motor has a mechanism. a spring-loaded lever sitting on side of powerhead. Is has three functions, one to prevent you from starting in gear and jumping over the transom as boat quickly acceleretes forward, away from you ( pretty good ingeneering - right ) and two avoid that you shift into gear at high trottle and damage gears, and third not reverse with too much trottle. This mechanism will lock the trottle, if you kill motor ( or it dies itself ) in gear, and you force it in neutral without turning throttle down first. Shift it into gear, turn tiller gas handle down to shift, and take it to neutral again. Check as master Joe says, that everything is fine.

 

[Joe Reeves]

Re: 25 hp screaming hi rpm in idle poss

As an added thought....... if you've had the flywheel off and neglected to torque the flywheel nut down to factory specs, it's possible that the the key has sheared BUT only so slightly, not enough to throw the engine out of time but enough to advance the timing a very slight bit. This doesn't happen often BUT it has happened.

Also check the carburetor throttle butterfly to make sure that it hasn't somehow jammed in the open position.

 

[american angler]

Re: 25 hp screaming hi rpm in idle poss

thanks for the replys

after i was able to start it in idle poss it was bk to running normal but i wouldnt go past half throttle on my next move for fear it would scream hi rpm's again for some reason the plate under the flywheel is getting jammed even when the motor shuts down at low idle and in gear when off i shift it to neutral and then on restart it will scream hi rpm's again i can move the plate bk to get a normal idle

i never had the flywheel off im thinking for some reason when i shift it to meutral when i stop it running in gear its turning the plate to wide open and getting stuck

i will look it over really good on sunday and let you know if i find anything

Thanks
AA

 

[american angler]

Re: 25 hp screaming hi rpm in idle poss

G Dane was correct

this only happens when the motor shuts down while in gear. when put in nuteral with out returning the tiller handle to the idle stop the vertical arm jams the plate under the flywheel causeing it to be stuck 1/2 -3/4 open causing the motor to scream on start up ( wont let the plate return to idle start)

so if the motor stalls while in gear, before u put the shift lever in nuteral, u must return the tiller handle to the idle poss stop while in gear, then put in nuteral and ck the start rotation of the tiller handle ( before start up )to make sure that its hitting the plate stop on the vertical arm for start up

i noticed any slight turn on the tiller moves the plate like it should but that the vertical arm can jam the plate in any tiller poss off start idle if u put shift lever in nuteral every thing else looked to be ok

thanks for your support

i just have to ad a kill switch for safty ( there isnt 1 )

American Angler

 

[jspringator]

Re: 25 hp screaming hi rpm in idle poss

My 75 has a kill button, but no wrist strap that kills the motor if you are thrown overboard. There has to be an easy way to add it. Does anybody know how to do it?