tiller handle vibration 2stroke verse 4stroke

[markofwisconsin]

Everyone seems to be going to four stroke outboards these days. Four years ago I purchased a Lund SSV 14 with a 15HP fourstroke Yamaha, with a tiller handle. The handle vibration on the tiller was so bad it would put my hand to sleep. The next year I traded it in for a new 25HP twostroke Johnson, with tiller steer. Much more enjoyable no vibration. Is this common, or just an isolated case?

 

[rndn]

Re: tiller handle vibration 2stroke verse 4stroke

An isolated case. I love 2 strokes but I would think they would always vibrate a little more than a 4 stroke. A lot also depends on how well the vibration is dampened with rubber mounts. It's very possible the other motor was not isolated as well as the newer Johnson.

 

[F_R]

Re: tiller handle vibration 2stroke verse 4stroke

Take an average basic two stroke and an average basic four stroke without all the vibration suppressing tricks and the two stroke will have WAY less vibration than the four stroke. The only reason either one of them is tolerable by todays expectations is because of the mountings and silencing that are used, as well as the internal balancing engineered in. Number of cylinders and their configuration also figures into the overall result.

 

[JB]

Re: tiller handle vibration 2stroke verse 4stroke

Setting aside the isolation engineering for a moment. . . .

In one revolution of the crank a twin cylinder 4 stroke has one power stroke and the 2 stroke twin has two. It is power strokes that produce vibration (torque reaction). That suggests to me that the 2 stroke twin would seem to vibrate less because it would vibrate at a higher frequency (double) than the 4 stroke. The four stroke also has a 360* crank, which is much harder to balance than the 2 stroke's 180* crank, which is naturally balanced.

Now, that said, I have owned one 4 stroke twin and many, many 2 stroke twins. The little JohnnyRude 3s from the 60s were the smoothest of all, but the 1997 Johnny 9.9 4 stroke (OMC-made) was also very smooth.

Bottom line? I think differences in what the maker does to isolate vibration makes more difference in the end than whether it is 2 stroke or 4 stroke.

 

[steelespike]

Re: tiller handle vibration 2stroke verse 4stroke

I think the 2 stroke is smoother. Take the old Gale 3 single certainly a primative single if there ever was one. Folks say it vibrates some but not to the point of numbing vibration.Now take the Briggs 4 stroke vibration is about the first thing mentioned numbing vibration.A 2 stroke has twice as many power strokes at about half the power per stroke should be smoother.
Idle is a little different as a carbed 2 stroke will be a little rougher.

 

[Scaaty]

Re: tiller handle vibration 2stroke verse 4stroke

You can feel every power stroke on my older 5hp Honda 4S, not so any of my 2 strokes

 

[EMM]

Re: tiller handle vibration 2stroke verse 4stroke

I have a Tohatsu 25 4stroke and it is the smoothest engine I have run.

 

[steelespike]

Re: tiller handle vibration 2stroke verse 4stroke

The Tohatsu 4 stroke is a 3 cylinder there are more power strokes spaced better.some 2cyl 4 strokes the pistons go up at the same time with the power strokes 180 degrees apart.so you have powerstroke vibration and piston mass moving adding to the vibration.did you ever watch a Harley idle at a light same basic engine design.

 

[BoatBuoy]

Re: tiller handle vibration 2stroke verse 4stroke

Hmm...Glad Harley-Davidson doesn't make outboards. It'd be a one-horse race for "most vibration".

 

[EMM]

Re: tiller handle vibration 2stroke verse 4stroke

My dad has a Suzuki 25 horse, and my father-in-law has a yahama 25 horse. They are both 2str. 3cyl. engines. My Tohatsu is smoother than both.