F-Ribs And Sibs - Inflatable Boat Community

Mercury 8hp or Mercury 9.9hp (2 stroke)

In real world terms what's the difference? (yes I know it's 1.9hp )

Looking for a motor to drop on the back of my 2.9m B-Square.
Transom plate rates the boat @ 9.9hp and being a bloke I naturally want to fit it with the biggest motor possible!

I've come across a few 8hp merc's and was wondering how much difference, if any I'd notice with the 8hp over the 9.9hp?

Does anybody know if they are basically the same motor with different carbs?

Hi Andy

What year are the motors you are considering?

Typically the 8 and 9.9 are similar block size just different carb setup. If it were me I would put the 9.9 on the back as although it's a small power gain it will make a difference if you are loading up your boat or face punching a tide.
Simon

simonb wrote:Hi Andy

What year are the motors you are considering?

Typically the 8 and 9.9 are similar block size just different carb setup. If it were me I would put the 9.9 on the back as although it's a small power gain it will make a difference if you are loading up your boat or face punching a tide.
Simon

Hi simon,
As I thought,
So the 9.9 is a re-carbed 8 or the other way round?
I'm looking at the last generation of the smokers.
Typically the 9.9's are selling for nearly double the price of the 8's.
Winters coming so lets see what end of season bargains pop up.

I will probably hold out for a decent 9.9.

8hp is carb restricted essentially a different jet size.

Keep any eye out on all the useful places and one will pop up for sure. So people are living in dreamland when it comes to valuing their outboards so haggle hard

simonb wrote: If it were me I would put the 9.9 on the back as although it's a small power gain it will make a difference if you are loading up your boat or face punching a tide.
Simon

+1
Totally agree with what Simon says
You never know what the weather and sea conditions may throw at you

Paul

simonb wrote:8hp is carb restricted essentially a different jet size.

Keep any eye out on all the useful places and one will pop up for sure. So people are living in dreamland when it comes to valuing their outboards so haggle hard

The 6& 8 Share the same parts however the 9.9 10 XR10 & 15 HP have bigger pistons fitted, so the 9.9 has a larger capacity than the 6 & 8 HP

6&8 HP = 209 cc
9.9- 15 = 262 cc

Hope this answer the question but the 9,9 will have substantially more power,

I think you will find the weight of most 9.8 and 15hp engines are the same weight approx except in the case of Honda where the weight of the 8, 9.9, 15 and 20hp are all within a few kilos of each other. I have always bought the max size engine for any of my SIBs / RIBs / FRIB and perhaps bought a small engine for pottering around on fresh water. A 15hp Parsun and a 2.5hp mariner at the moment.
You must take into account what the max payload will be and build your outfit with that in mind then you are covered for all activity.

Phil

How long have you had the 15hp Parsun?
Any problems with it?
What's the build quality like?

I have had the Parsun for just over a year with no problems whatsoever. They buy in Yamaha engines and finish them so they are not crap engines to start with. I have several friends with them and again no issues.

I find them to be as well put together as any other engine and lets face it, many of the engines around are made by other manufacturers including some of the OMC engines as I understand it. Tohatsu make a number of smaller engines with other makers names on them, it is the way of the world and has been happening in TV, video/DVD players, washing machines etc for some years.

Phil