ox66 250 efi mods

**slowoutboard** · 02-03-2016, 08:07 AM

Have a 2001 yam 250 efi with 300 hrs that i was thinking of doing a few mods to up hp .is it worth doing anything or just wasting time. Motor is on a 26 scarab cc,boat runs about 49 -52 depending on load. Boat has a pad on the last 10 ft of hull so it gets up and runs fast for a single. Thanks

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**Todd D** · 02-03-2016, 11:48 PM

http://yamaha-rebuild.com/Yamaha%20High%20Perf.htm

Call Wayne

**Mr. Demeanor** · 02-04-2016, 12:45 AM

You may get better bang for the buck tweaking your setup. Setback, prop testing / mods, etc.
If the motor needed rebuilding you could make some more power to go faster but most of the bolt on stuff will maybe make it accelerate a little better.

I would spend the money on props and maybe a jackplate.

**Brabender** · 02-04-2016, 06:52 AM

I agree with demeanor.
work on setup and props. Much to be gained there

**ghost28** · 02-05-2016, 09:21 PM

Leave it stock....play with setup and just go boating....

**ghost28** · 02-05-2016, 09:23 PM

That boat is similar to my 27 concept I had....With a healthy 250 merc properly set up it ran 60 to 62 at any time....when i first got it with the wrong prop and crap setup it only did 54.....

**tres** · 02-06-2016, 07:14 AM

you can tweek your engine... but best gains are in set-up...just like the above guys mentioned

**Superbender** · 02-06-2016, 11:14 AM

Originally Posted by tres

you can tweek your engine... but best gains are in set-up...just like the above guys mentioned

Awesome advice tres,Now pay attention to your own advice

**slowoutboard** · 02-06-2016, 11:22 AM

The problem I have is I have a parachute for a t-top and trying to push it faster I feel I need more horsepower. I run a merc Mirage 19 inch pitch prop on it the big round ears give me good bow lift have gone 52 with that prop before I lost it.shaft nut came off

**ghost28** · 02-06-2016, 02:23 PM

Mirage prop is crappp....old school technology....that boat will wake up with a Merc Rev 4

**slowoutboard** · 02-06-2016, 03:51 PM

with 4 blade do you keep the same pitch or go down 1

**Superbender** · 02-06-2016, 05:42 PM

How many Rpms are you spinning that mirage?

**ghost28** · 02-06-2016, 07:05 PM

Originally Posted by Superbender

How many Rpms are you spinning that mirage?

what he said.....RPMs??

**slowoutboard** · 02-07-2016, 07:15 AM

trimming up a little i can get 5500 out of it

**Mr. Demeanor** · 02-07-2016, 08:38 AM

Give Ken at PropGods.com a call and see what he thinks. Tell him Mr. Demeanor (Chris) sent you his way. He will talk to you about props and has a testing program. Probably already has data on your boat.
Dont discount that MIrage Plus. Its the fastest prop on my Fountain and we have tried them ALL and at different heights. They do respond very well to a little work including some extra cup.