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shaky 2006 15 hp johnson 4 stroke

S

sarducci

Member
I have a 2006 15 horse jhonson and when im running it it has a bad vibration. ive put new plugs in it and cleaned the carb any thing else i can try myself?
 
Re: shaky 2006 15 horse johnson 4 stroke

Yes, they vibrate!
Remember that in a a 2 cyl 4-stroke, both pistons move in parallel up and down at the same time. On a 2-stroke, one on 'top' -the other at the bottom.
In order to balance this out, they add extra parts like 'balance shafts'. However the 'balance' between added weight, improved balance etc is at the end a compromise.
In general the lower the rpm, the smother the ride, but give it full throttle, and it really is a 'butt shaker'. It does not get netter that the whole leg and lower unit parts including vibration dampers are from the 2-strokes and not specially designed for the 4-strokes.
I've had a couple of those engines in my time, they are excellent as trolling engines, but running at full is a torture!
 
Re: shaky 2006 15 horse johnson 4 stroke

so i guess im stuck with rattling all my brains out!!!!!!!!! The prop has a lil bit of damage but it vibrates real bad even in neuteral. it isnt bad trolling at an idle but if i give it just a lil throtle it is bad and annoying as hell to me and probly the big stripers im after!!!!! What if i put sum rubber or foam on the transom where it is bolted on think that will help? Thanks for any and all help!!!!!
 
Re: shaky 2006 15 horse johnson 4 stroke

Check your exhaust in the leg. I have seen many smaller 4 strokes that get a build up of crap in the exhaust and it causes back pressure. I know the Merc's are notorious for it.
 
Re: shaky 2006 15 horse johnson 4 stroke

Get your prop checked at at a prop rebuild place. And I still say get your prop shaft checked for not being bent.
 
Re: shaky 2006 15 horse johnson 4 stroke

I find this shaking issue rather interesting in that twin cyl motorcycles like Honda CB, CD and SL twins have pistons rising and falling at the same time. Yamaha and Suzuki twins were the same. No hint of vibration even up to 7000rpm. They ran one set of points with wasted spark each alternate exhaust stroke.

So, same thing here but an outboard.

Vibes would mean that engine mount/isolation may be a problem? My Old 35 Evenrude has just done its top front mount..............let me know straight away with all sorts of vibes and buzzing through the transom etc.

I would look further away from the integrety of the actual powerhead (Except mounts) and have a squiz at other turning parts further down...........or flywheel may be about to fall off?

Also, what is this that four strokes build up "Crap" in the exhaust system? Four strokes are supposed the answer to nasty oily two strokes? Clean and green?
Interesting this!

Regards

B
 
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