'81 Evinrude 35hp knocking/shaking

[romaniawhaler]

I've been reading the forum for a while learning great info.
However I am not able to determine what problem I am experiencing.

When the engine is running at half-throttle it runs perfectly, but when it is at full throttle and cruising along, every 45 seconds there is a "kick" or "shake" from the whole engine, the whole boat feels like it is running over something in the water.

I should mention I just had the carb-rebuild professionally and replaced the spark plugs, also replaced the whole wiring harness.

Is it bad if I let this continue to happen?

 

[jonesg]

Re: '81 Evinrude 35hp knocking/shaking

bump..

 

[Sandhammaren05]

Re: '81 Evinrude 35hp knocking/shaking

Be more specific: is the motor missing a beat (misfiring suddenly) or does it feel like something mechanical, like a gear tooth skipping a beat? Without more info no suggestion can be given.

I've been reading the forum for a while learning great info.
However I am not able to determine what problem I am experiencing.

When the engine is running at half-throttle it runs perfectly, but when it is at full throttle and cruising along, every 45 seconds there is a "kick" or "shake" from the whole engine, the whole boat feels like it is running over something in the water.

I should mention I just had the carb-rebuild professionally and replaced the spark plugs, also replaced the whole wiring harness.

Is it bad if I let this continue to happen?

 

[romaniawhaler]

Re: '81 Evinrude 35hp knocking/shaking

I'm sorry I'm still getting used to the lingo..

It feels like it is misfiring, not skipping a gear.
It doesn't come out of gear, quite the opposite it is hard to put it in gear.
If you look back at the engine it produces a large shake when this happens.
Also looking at the back the two little exhaust holes "spurt" out exhaust at intervals instead of evenly, the pee hole shoots out water evenly however.

I put SeaFoam in the gas tank because a local boat mechanic suggested it would clean out the engine if it hasn't ran for a while, could this have offset the gas/oil mixture and make the engine run unproperly?

 

[romaniawhaler]

Re: '81 Evinrude 35hp knocking/shaking

bump..

I'll give some more details, the actual shake or "going over a log" feeling doesn't start until about 20 minutes into the boat ride and then continues every minute.

It is hard to shift it into gear, but the mechanic said it's just the wires and I shouldn't worry about it.

My main reason for thinking it's not "skipping a beat" like you said sandhammaren, is because it does not feel like it stops getting power at any time while this is happening. Doesn't feel like it stops and starts like skipping a beat would be. It simply jumps while running.