Is a motor shaking/vibrating at idle normal? Video

[erikpn]

Thinking about buying a used late 80s/early 90s 80hp merc from a dealer. But I noticed it tends to shake and vibrate at idle while we had it on the hose. Is that normal? My old outboard does it too... but that runs like crap. Vibration stopped once it was up at higher revs.

It looks kind of like these
Mercury 80hp - YouTube
Jay's 1989 Skeeter with 80hp Mercury Triple - YouTube

 

[orbanp]

Re: Is a motor shaking/vibrating at idle normal? Video

Generally two stroke motors do not idle smooth without load.
Also, a crossflow type engine would idle smoother than a loopcharged two stroke engine.
A loopcharged engine would have more power and better fuel economy than a crossflow engine.

Peter

 

[BonairII]

Re: Is a motor shaking/vibrating at idle normal? Video

Is compression even across all cylinders?

Doesn't seem like much vibration in the vids.

 

[emckelvy]

Re: Is a motor shaking/vibrating at idle normal? Video

The motor in the video sounds fine to me! A Big Triple will never idle as smoothly as an Inline Four or Six. Some vibration at idle would be from the inherent 3-cyl engine balance, but once you're off-idle it should be fairly smooth (and that's normal for one of these).

A good buddy of mine rebuilt a 90-hp Triple for his old 16' Lo-Pro ski boat, and it felt like it ran about as strong as an old 100hp Six when we were skiing with it.

Much easier on gas, though, and very quiet compared to the old T.O.P.

Just think of the 80hp as 1/2 of a Tower of Power and you'll be OK! Just imagine a T.O.P. made of 2 of 'em, it'd be Killer!

Cheers.........ed