Mariner - Difference between Tohatsu and Yamaha

[Akira]

Hi guys,

I just got a mega-super deal on a brand new Mariner 25 HP 2 stroke. The poor thing was bought and put in the garage in 2004, and never seen the water. So I got it without ant scratch or dent, the gear oil never changed, the implelor still original.

I was wondering if I can get it uprated to 30hp. I have red the threads about, but the engine I have seems different. How can I tell if this is a Yamaha or Tohatsu?

The flywheel is not dented, is plain like on the pics (from Internet, but mine is similar) and the numbers are marked from 0 to 40 in both directions.

http://i1231.photobucket.com/albums/...psa79e2538.jpg

http://smalloutboards.com/images/mer...nsideside2.jpg

Could anyone tell me if this engine is upratable to 30 HP? Thanks to help

P.S. Serial number OP290850
Book stamped 09-10-2004

[beamishken]

That's not a yamaha it's the Mercury version mariner
Not sure if they were badge engineered tohatsu engines
As for upgrading look for threads about upgrading mercury 25

[Max...]

IIRC isn't it as simple as removing the restrictor gasket on the carb on this engine, £12 or something??

[Akira]

Thanks for replies, guys, very good news about the up rating possibility
This week end I will post few pictures to be sure, if you could take a look, thanks

[samt]

If yours looks like this under the hood, then yes you can upgrade (image below) If its the same as your top image, then no you can't. Your second image is of a 15hp btw.

It wouldnt be yam based in 2004.

[Akira]

Originally Posted by samt

If yours looks like this under the hood, then yes you can upgrade (image below) Attachment 114353

Samt, that's the point, it does not look like this. The flywheel is completely round, as on the pics I gave the links to, no any indentation at all.

[Northern Pike]

If you remove the air restrictor then you must install a larger main jet to maintain air/fuel balance. Otherwise you'll run too lean.

[Akira]

Originally Posted by Northern Pike

If you remove the air restrictor then you must install a larger main jet to maintain air/fuel balance. Otherwise you'll run too lean.

Thanks, mate, do I get it from the 30hp model?

There were many talks about this update, and I saw only the air restricting gasket replacement and some carb adjustment, but nothing about a bigger main jet?

[Northern Pike]

I don't know about Mercs. I did this with an OMC. Went from 20 to 25. I searched the parts micro fiche to see what parts were different. I suggest you do the same. See if the exhaust tuner (chamber, whatever) is the same too.

You could probably just enlarge the hole in the existing air intake. That's what I did.