2009 5hp 2 stroke runs rough

Is it normal for these little 2 strokes to run a bit rough, sort of vibrate?

Ive put 20 litres thru it on the water, it puts a vibration thru the whole boat (12ft aluminium) at medium throttle, smooths a bit at WOT but can still feel it.

Is this normal for this model?

Im used to to much bigger engines which were all smooth.

Prop looks OK.

I remember local yam dealer mechanic commented to me the little 2St 5s' run rough as, when I asked him about oil ratio, he said "they run 100:1, dont run 50:1 as they run rough enough as is!"

I recently bought this motor 2nd hand from private guy, in excellent condition, looks new. Previous owner said 10 hrs use only. He could be right.

need to check the prop and propshaft

the shaft seems straight, cant see and bend by eye, every blade on prop looks identical......

My original question; does this model natuaraly run rough, as my local Yam dealer said?

yes they do if it is a twin

the way its clamped on the transom can cause vibration. i have seen a piece of rubber from a tire tread used to reduce that vibration.

Its a single cylinder.

Thanks, ill try the rubber.