Mariner 25hp upgrade?

[C2 RIBS]

I have just bought a 2006 Mariner 25hp 2 stroke and have read a few quotes here that it can be upgraded to 30hp. Is that correct and if so is it worth the extra costs please?

[Turbodiesel]

Hello, Yes you can, its very simple. Just remove the restrictor from behind the carb, and fit a 30hp carb gasket. But if your engine still has any warranty left you could void whats left of it if anything goes wrong.

[C2 RIBS]

Thanks turbodeisel, I will check if any warranty, but then is it worth doing, i.e performance and fuel use etc. I intend to put a prop guard on

[Locozodiac]

Originally Posted by C2 RIBS

Thanks turbodeisel, I will check if any warranty, but then is it worth doing, i.e performance and fuel use etc. I intend to put a prop guard on

Have no experince with prop guards, been reading that slows you down a bit, even have to change prop pitch to compensate, in that case update to a 30 HP for that big size Quicksilver 430 if planning to use prop guards.

Happy Sibbing

[Turbodiesel]

Originally Posted by C2 RIBS

Thanks turbodeisel, I will check if any warranty, but then is it worth doing, i.e performance and fuel use etc. I intend to put a prop guard on

Yes itw worth it!. Prop guards can take anything upto a third of your hp depending on which type you go for!!!

[Easyrider]

Originally Posted by Turbodiesel

Hello, Yes you can, its very simple. Just remove the restrictor from behind the carb, and fit a 30hp carb gasket. But if your engine still has any warranty left you could void whats left of it if anything goes wrong.

I notice you work for Barrus- is it correct that you have to advance the ignition by 5 deg too, to get the extra power.

[C2 RIBS]

so which prop guard should i buy to prevent this power loss you mention?

[Locozodiac]

Originally Posted by Easyrider

I notice you work for Barrus- is it correct that you have to advance the ignition by 5 deg too, to get the extra power.

If you engine is currently adjusted to 20º, you won't have a full open throttle.

If you engine is already delivered to 25º just change the carb gasket by a 30 model (it's much air wider than restricted 25 gasket)

If your engine is adjusted to 20º, advance to 25º to full throttle, and see if the butterfly is at 180º, adjust by means of stopper. Will have the extra 5 HP at the end for better hole shot, carrying more weight, use on larger boat, etc.

So not to get mixt-up, don't know if all Mariners/Mercury/Tohatsu's 25's are being delivered worldwide to 20º/25º, a matter to check out on each one's individual engine. All cowl 30's are delivered to 25º.
Note: this info is on the 25/30, 2 strokes tech service manual.

Happy Boating

[Locozodiac]

Originally Posted by C2 RIBS

so which prop guard should i buy to prevent this power loss you mention?

Very thricky question: a matter of experiment under trial/error with different pitch propellers untill full wot max rpm is achieved for that engine model.

[C2 RIBS]

Cheers for everyones knowledge. Engine good after service and just out of warranty, it is fixed to 30hp and have fitted a guard called propguard, an 11inch model for this engine, so will have to see how it performs when next out and then tinker with your ideas. Cheers Ian