Derestriction

[mister p]

Is there any reversible restriction on a Mariner 8 hp two stroke?
I suspect there are another few horses lurking in there.
Unless I already have them as it punches above its weight.

[Boats&Outboards]

Don't take my word for it but I think that's an uprated 6HP.

The 9.9 is upgradeable to 15HP so that kind of leaves nowhere for the 8 to go. I think the models are as follows

2.5/3.3 4/5 6/8 9.9/15 20/25/30 40/50/60 75/90

Peter ~ Boatsandoutboards4sale ~ askboatsandoutboards4sale@sky.com ~ 07930 421007

[Downhilldai]

6, 8, 9.9/10, 15 Merc/Mariners are all based on the same motor.

[mister p]

BoatsandOutboards reply appreciated.
Downhilldai, I will push you further on this. So what parts are variable in order to up my power?

[Boats&Outboards]

Originally Posted by Downhilldai

6, 8, 9.9/10, 15 Merc/Mariners are all based on the same motor.

Surely a 6hp cannot be taken upto 15hp though ?

Peter ~ Boatsandoutboards4sale ~ askboatsandoutboards4sale@sky.com ~ 07930 421007

[captnjack]

I'm sure you could squeak another HP or so out of a 6/8hp block. You'll probably give up something in the process (no free lunch). If you might want to read this rather dated but valid book, "2 stroke Tuners Handbook" Gordon Jenning's Archivek

[Downhilldai]

Originally Posted by mister p

So what parts are variable in order to up my power?

There was a recent thread on this where we hoped a Merc dealer would give us the answer. May be worth a search on this site. Alternatively, you could take a look at the parts listings on the Merc website to see where the specifications of the 2 motors differ.

[Turbodiesel]

I have just had a look into this. The pistons are different on the 6 and 8hp engines. Also the Cylinder blocks have a different part number from the 9.9 and 15hp.

[Boats&Outboards]

Originally Posted by Turbodiesel

I have just had a look into this. The pistons are different on the 6 and 8hp engines. Also the Cylinder blocks have a different part number from the 9.9 and 15hp.

So would that would suggest the 6/8 are interchangeable as are the 9.9/15 but not a 8/9.9 for example ?

Peter ~ Boatsandoutboards4sale ~ askboatsandoutboards4sale@sky.com ~ 07930 421007

[Downhilldai]

Sounds like a powerhead swap may be needed.

[Fenlander]

Effectively there's a big fence between specs of the Merc/Mariner 6/8.... and the 9.9/15.

6 & 8 have the same capacity, bore, stroke, basic carb design, gear ratio and weight as each other.

9.9 & 15 similarly share all the same aspects with each other but all those aspects are completely different to the 6/8 models.

[Boats&Outboards]

Originally Posted by Fenlander

Effectively there's a big fence between specs of the Merc/Mariner 6/8.... and the 9.9/15.

6 & 8 have the same capacity, bore, stroke, basic carb design, gear ratio and weight as each other.

9.9 & 15 similarly share all the same aspects with each other but all those aspects are completely different to the 6/8 models.

That was my understanding of the models also. I'd assume that to be the case throughout the range.

Peter ~ Boatsandoutboards4sale ~ askboatsandoutboards4sale@sky.com ~ 07930 421007