Engine vibration

[dee.yeah]

I have been curious about this "minor" problem for long.

The 2YM15 on my Y25 vibrates vigorously when the engine is running between 1500-2000rpm. The vibration is so hard that the whole boat is vibrating with big noise. What could be the cause(s) and is there anyway to minimize it?

Thanks!

 

[Boffin]

My 1GM10 made the boat vibrate at some 2800rpm, but still manageable . It is just MORE vibrate than at other rpm.

There may be many reason :

due to natural resonance , the vibration of the engine synchronize with the boat's natural resonance properties . That is no way to prevent , you just stay clear from that rpm.

check whether the clutch of gear box is in good order . It happened in my old engine once . disconnect the gear box and run at 1500-2000rpm and see what is happening .

do you have a clean propeller??

 

[dee.yeah]

The vibration stayed the same either my propeller is clean or dirty.

It appears to me(I guess) it is the boat's natural resonance.

 

[g5665]

had you guys tried to change the rubbers under the engine? i changed mine when they refit the engine and no vibration in my YSM8 ( or maybe too old and weak )

 

[seouljoe]

I had same problem with short shaft 5HP Yamaha ,
Went back to Nissan long 8HP ,, Had to raise the transom with stainless steel beracket ,, made by my friend. No vibration now ,,
I strongly suggest thick rubber under the engine mount then another layer of old car floor mat,, worked for me.