Excessive vibration

[miluemta]

Hi all,

I have a 12' aluminum boat with a 5hp mercury. I ran it for the first time the other day and the boat and motor vibrates something fierce. The top speed is about 5 mph. I ran the same motor on a 12' polyethylene boat and it went about 15mph with no vibration at all.

Is there a way to dampen the vibration or is there something wrong with the engine? It seems like I'm losing power to the vibration. I also noticed some small nicks on the prop, that wouldn't throw off the balance that much would it?

If I get a new prop and want higher top speed, what pitch should I move to? It currently runs a 8 3/8" x 7 pitch, 3BL RH aluminum.

Any help is greatly appreiated, thanks.

 

[Tadd_P]

Re: Excessive vibration

dont believe you have a prop problem. Id say you are in serious need of a tuneup is all. Get some new plugs and clean up them carbs might be amazed at what you find man

 

[miluemta]

Re: Excessive vibration

Thanks, I didn't think anyone was going to comment.

Coincidently, this engine had sat in the garage for several (probably about 5 or 6) years but, was bought brand new and had only been ran twice before storing it in the garage.

We got it out, opened it up and it was still looking clean and new under the hood. We cleaned out the gas tank and fuel line, added 2-cycle mix and it started right up. It seem to run fine on the first boat then not on the second boat.

You think the spark plug is bad from sitting even though it hasn?t been used much? Is there anything else that might need maintenance (oil or greased)?

 

[diaric]

Re: Excessive vibration

if it was put away with gas in the carb then gum and varnish are most likely the problem. cleaning fuel pump and carb will likely solve it. running seafoam in the gas or injecter cleaner might straighten it out if its not that bad.

 

[miluemta]

Re: Excessive vibration

Ok, I think I'm going to change the plugs and run some seafoam since it's fuel injected and has no carb. Sounds like that will make a difference. I'll post what happens for future reference.