Removing 50 hp restrictor plate makes a 60 hp?

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Lynn
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Removing 50 hp restrictor plate makes a 60 hp?

Post by Lynn » Wed Aug 06, 2014 3:40 pm

Several shadetree mechanic friends have stated 2011 50 hp & 60 hp 4 stroke Yamaha OBs are virtually the same including ECUs. Supposedly, one can remove F-50 restrictor plate, kill electric power for 5 minutes, add water and you have a 60 hp Yamaha! Flashing ECU not required as it will "learn" the new airflow. Fact or fiction ? Any advice or warnings before I try removing restrictor plate ? ps: 2 U Tube videos and a moderator on refugeforms.com confirm statements above (but it IS the internet) . . . What do you experts think ?
1st post - I am a new owner of 2011 26M

raycarlson
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Re: Removing 50 hp restrictor plate makes a 60 hp?

Post by raycarlson » Thu Aug 07, 2014 7:52 am

Give it a try, if your rpm at wot with current prop increases from 300-400 rpm youll know if it worked..........

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mrron_tx
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Re: Removing 50 hp restrictor plate makes a 60 hp?

Post by mrron_tx » Thu Aug 07, 2014 6:16 pm

I wonder if that would work on a DF70a Suzuki :) Keep Us posted :) And what.... You don't think guy was a French model...Lol That's almost as good as Hump Daaaay :!: Ron.

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mastreb
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Re: Removing 50 hp restrictor plate makes a 60 hp?

Post by mastreb » Fri Aug 08, 2014 12:00 am

It won't cause any problems that putting it back won't fix.

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dlandersson
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Re: Removing 50 hp restrictor plate makes a 60 hp?

Post by dlandersson » Fri Aug 08, 2014 6:35 am

Crews do something similar with M1's MBT's all the time. 8)
Lynn wrote:Several shadetree mechanic friends have stated 2011 50 hp & 60 hp 4 stroke Yamaha OBs are virtually the same including ECUs. Supposedly, one can remove F-50 restrictor plate, kill electric power for 5 minutes, add water and you have a 60 hp Yamaha! Flashing ECU not required as it will "learn" the new airflow. Fact or fiction ? Any advice or warnings before I try removing restrictor plate ? ps: 2 U Tube videos and a moderator on refugeforms.com confirm statements above (but it IS the internet) . . . What do you experts think ?
1st post - I am a new owner of 2011 26M

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Lynn
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Re: Removing 50 hp restrictor plate makes a 60 hp?

Post by Lynn » Fri Aug 08, 2014 7:53 am

raycarlson wrote:Give it a try, if your rpm at wot with current prop increases from 300-400 rpm youll know if it worked..........
-----------------

Yup, got increase of 400 rpm WOT (from 4,400 to 4,800) & about 10% increase in speed (11 to 12.1 knots)
But did not get 20% increase overall: 50 hp + 10 hp = 60 hp (so suspect other changes needed)

Current prop is 10.375 x 11 (3 blade) so ordered Solas 12.2 x 8 (3 blade) & will install this weekend - will advise
(Yamaha prop selector runs 12 x 8 on pontoons - the closest match to M's 2,500# weight)

Hoping to get WOT up to mid-range recommended by Yamaha for F-50 of ~ 5,500 rpm (top speed not as important - although would like to teach 16 year old grandson to waterski)

(Sailboat run lightly loaded, board & rudders up, ballast empty, 1 person & 200 #s fuel & water/sodas on board) :macm:

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Lynn
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Re: Removing 50 hp restrictor plate makes a 60 hp?

Post by Lynn » Sat Aug 09, 2014 5:36 pm

Final update . . .
new 3 blade 12.2 x 8 Solas prop installed
WOT now 5,300 and speed 13.8 knots
Guess that all she'll do - unless I go to 90 hp
So I'm happy - even tho NO 22 mph - oh well 8)

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Whipsyjac
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Re: Removing 50 hp restrictor plate makes a 60 hp?

Post by Whipsyjac » Sat Aug 09, 2014 11:44 pm

Lynn,

Do you have the owners manual for your outboard? What's the gear ratio?

Your final engine performance numbers are almost identical to my :macx: with my 1996 Mercury 50hp 4 stroke (not big foot)running medium load(homeward run from cruising). I did get a Michigan Wheel 4-blade 12"x9"pitch and loaded down get 12kts at 4800 and medium just kiss 5500rpm at 13.7kts or so popped over 14 a couple times on the calmer water.

Thinking of getting a bigfoot lower so that with the gear reduction I can get the rpm up...numbers look like I won't increase prop speed at the very top end but I should do better when loaded heavy plus my new prop has an exchangeable hub so I just have to get a new hub to match the different splines of the bigfoot. Then once I establish my performance I could get a larger diameter prop for less slip and maybe a better top speed.

Willy

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Lynn
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Re: Removing 50 hp restrictor plate makes a 60 hp?

Post by Lynn » Sun Aug 10, 2014 11:07 am

Willy:

Yamaha Owners Manual says "Gear Ratio F50TR 1.85 (24/13)"
I'm not sure what this means (I'm not tech savvy)

I'm done messing with engine and props - probably could go larger diameter,
but I am now happy with what I'm getting from a 50 HP Yamaha: 5,300 WOT and 13.8 knots

After all, it's just a kicker to a sailboat . . .
& I seem to be getting max performance from engine that came with the boat (I'm 2nd owner) 8)

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Whipsyjac
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Re: Removing 50 hp restrictor plate makes a 60 hp?

Post by Whipsyjac » Sun Aug 10, 2014 11:36 am

Hi Lynn,

Your gear ratio means your engine turns 1.85times for every time the prop turns.

So 5,300 Rpm at engine = 2,865 Rpm at prop

Mine is a 2:1 so at 5,500Rpm engine = 2,750Rpm at prop but I have a 4 blade with 9" pitch so we end up at nearly identical boat speed

I ran the numbers and you have about 30% slip(you're only traveling 70% of the theoretical speed)
I have about 35% slip as I was medium to heavy load returning from a multiday cruise.

I'm hoping to change my lower leg to a bigfoot(2.33:1) because it will let me run my current prop closer to max rpm and I can get a bigger diameter prop which will reduce my slip.

I have 10-3/4"x12P spare prop with custom cupped blades and it only gets me to 12.5kts at 6000rpm loaded for cruising ballast empty thats over 50% slip :o . Oh well its just a spare and it moves the boat well at hull speed.


I think "Don't worry...Be happy" is a great policy with boating. If your engine starts every time and runs smooth, you're 99% there 8)

Willy

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Re: Removing 50 hp restrictor plate makes a 60 hp?

Post by Y.B.Normal » Mon Aug 11, 2014 8:15 pm

I pulled my restrictor plate today.
Results:
Before- 11.2 mph @ 4800 RPM
After- 13.4 mph @5100 RPM with a top end of 14.5 mph @ 5100 RPM (down wind)
Crew: 1 S.O.B. @200 lbs.
Ballast: Full
Prop: Yamaha High Thrust p/n 68S-45941-00-00 (3X14"X11")
Hull: Anti-fouling paint
Load: Normal cruising load incl. 12 gal. fuel, tools, life jackets, anchors (2),ie: medium load and full ballast, sails in place on deck and mast in sail bag and cover.

I'm happy with the immediate results and will keep tabs on any changes.
It'll be interesting to see the numbers when I dump the ballast.

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Crikey
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Re: Removing 50 hp restrictor plate makes a 60 hp?

Post by Crikey » Mon Aug 11, 2014 9:58 pm

Your speed should go up by about two miles per hour. :)

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Re: Removing 50 hp restrictor plate makes a 60 hp?

Post by Y.B.Normal » Mon Sep 29, 2014 10:51 am

Removed restrictor plate earlier (See previous post.)
Tested the motor yesterday before pulling the boat for the season.
WOT, 2 S.O.B., No ballast: 16.1 mph @ 5400 RPM. No wind, calm seas. 8)

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Carioca
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Re: Removing 50 hp restrictor plate makes a 60 hp?

Post by Carioca » Wed Oct 08, 2014 4:02 pm

I have a 1998 Yammy 50 hp with a Yamaha 12 x 3 x 9 pitch prop.
Gets me 17 - 18 mph. at wot.

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Neo
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Re: Removing 50 hp restrictor plate makes a 60 hp?

Post by Neo » Wed Jul 08, 2015 7:22 am

Will this work for a 50 EFI?

Many thanks.
Neo

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