25hp 4 stroke vibration only at idle.

[riverrat27]

hello all.
after some at home work I'm here to see if you guys have any suggestions. I have a 2009 25hp 4 stroke on a 15ft flat bottom. as the title says I'm having a vibration issue with the motor Only at idle and low speeds. WOT the motor shows no vibration. my local shop looked at it and recommended I clean out my vst (which has been done) change fuel filter (done ) and then run a fuel treatment through it which I am doing. As I can tell the motor runs fine just this vibration is frustrating. Now I will say with what I have done I did notice an improvement. Is some vibration normal? Do I need my injectors cleaned?
thanks guys

To add: as the motor initially fires up it does not vibrate at all but as the motor idles down it starts to vibrate.

 

[gm280]

:welcome: aboard riverat27. Nice having you join us here at iboats...

I have never been around a 4 cycle OB engine running before, so I have two suggestions to check. If there any way you bend the prop by hitting anything? And have you ever installed a carb kit in it? If you have a bend prop, that can make more vibrations at slower speeds then higher speeds. And if your carb has never been cleaned with new fresh gaskets, it could have some idle ports plugged. So either condition can cause vibration...just saying... JMHO!

 

[riverrat27]

Gm280 thanks for the welcome and response as well. As for the prop it does have some scratches on two of the blades but nothing extensive, if the prop were the issue would it cause vibrations even when the engine is in neutral and the prop is not spinning. And Most of the knowledge I gathered 4 stroke engines do not have carbs? Correct me if I'm wrong.
thanks again

 

[gm280]

Gm280 thanks for the welcome and response as well. As for the prop it does have some scratches on two of the blades but nothing extensive, if the prop were the issue would it cause vibrations even when the engine is in neutral and the prop is not spinning. And Most of the knowledge I gathered 4 stroke engines do not have carbs? Correct me if I'm wrong.
thanks again

Okay very good points. No if the prop was bend it would not show up in neutral at all. So that rules out that problem. And I assumed your engine was carbureted. Again if it is fuel injected, that rules out a carb issue as well. So injectors can be dirty and even the plugs could be an issue. Have you cleaned the injectors and changed the plugs? Anything that is general maintenance type replacement items can cause your problem... However, you can expect some vibration more so with 4 cycle then 2 cycle simply because 2 cycle engines fire ever revolution and run smoother because of that... Again just saying because I've never own a 4 cycle OB engine...yet!

 

[riverrat27]

Okay very good points. No if the prop was bend it would not show up in neutral at all. So that rules out that problem. And I assumed your engine was carbureted. Again if it is fuel injected, that rules out a carb issue as well. So injectors can be dirty and even the plugs could be an issue. Have you cleaned the injectors and changed the plugs? Anything that is general maintenance type replacement items can cause your problem... However, you can expect some vibration more so with 4 cycle then 2 cycle simply because 2 cycle engines fire ever revolution and run smoother because of that... Again just saying because I've never own a 4 cycle OB engine...yet!

Plugs have been changed but I've not cleaned the injectors. Can some basic maintenance be performed at home as far the injectors? I was looking at a couple companies that will clean them for you.

 

[Silvertip]

Did you just acquire this engine or is this a problem that just popped up? As I remember that motor is a "v-twin" and as such they do vibrate at idle. Perfectly normal if that's the case. Think Harley Davidson here.