25 hp Johnson engine clicks randomly at high RPM

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halftrack

Recruit
Joined
Apr 19, 2010
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3
1995 25hp Johnson I hear a random clicking from the motor at 3/4 throttle and above more throttle more clicking . it may run good for a few seconds then click/rattle 3-5 times quickly then run smooth again for a few seconds. Half throttle and below is good. Idles and starts good . Pulled plugs and they are clean and look good. I'm thinking it may be a reed valve, but would like any thoughts before I tear into it. Any help appreciated
 
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halftrack

Recruit
Joined
Apr 19, 2010
Messages
3
Re: 25 hp Johnson engine clicks randomly at high RPM

I pulled of the intake and reed block, looked inside and all seems good rods .bolts and pistons look good, Crank is good nothing appears wrong. While turning the flywheel to move the crank shaft I notice the plate under the flywheel moves each time the flywheel is rotated. The one with the coils and pickup mounted to it. I pulled the flywheel and all looks good under the flywheel. Is it just the magnets in the flywheel pulling on the iron cores of the coils that caused it to move and is this normal ? My first small motor and I need some Information that is not in the manual Thanks
 
F

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: 25 hp Johnson engine clicks randomly at high RPM

Well, perhaps we have a matter of word choice here. "Clicking" ??? Are you sure it isn't jumping out of gear and instantly back in? That is more than a click. More like feeling like you hit something in the water.

As you found out, it certainly can't be the reeds.
 
B

blimp

Petty Officer 1st Class
Joined
Sep 30, 2009
Messages
237
Re: 25 hp Johnson engine clicks randomly at high RPM

That base plate should only rotate, not move with the flywheel. Sounds like the plate is loose or something else is wrong under the flywheel. Is it pull start? if so, maybe try starting it with pull start off and see if the clicking goes away.
 
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halftrack

Recruit
Joined
Apr 19, 2010
Messages
3
Re: 25 hp Johnson engine clicks randomly at high RPM

It is the base plate that moves and it is in the direction of rotation of the flywheel. As best I can describe the noise is an old can of spray paint that had a metal ball inside to mix the paint. sounds like when you shake it hard a few times then count a few seconds then shake it up again. As it will not make the noise at idle or just reving the engine it is hard to tell where it is coming from running down the lake at higher RPMS. I do not think it is jumping in and out of gear as the pull is constant and smooth.
 
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