convert 40 HP Merc to 20 HP

overpower

Recruit
Joined
Sep 5, 2010
Messages
4
The local lake I fish on has 20 HP max & so when jawboning with my brother in law over a breski...yeah, happy my sister married him & not the hippy...wondered whether the 40 can be converted to 20. Idea would be to show Smokey the Bear the repair bill and cert from the local shop that the motor was converted down to 20 so as not to get fined!

Details: Have a 2003 40 HP Merc elec start, remote and a 9.9 kicker on a 16 ft boat. Runs great, but the local lake I fish on has 20 HP max...and the kicker really doesn't move the boat much (plus it's a pain to operate). Looked at selling the 2 engines and buying a 20 HP...but the cost of doing that was $2,500 ($4K for 20 HP, $500 work, rebate on the 40 and the 9.9 = $2K).

There are few other good lakes around, so I really don't mind permanent mod to 20...but it would be great if I could just chuck parts (smaller carb?) in my basement and retro back to 40 when I sold it...or perhaps moved to somewhere that the 40 would make sense.

Thanks for any advice.
 

kenters

Cadet
Joined
Jun 25, 2010
Messages
23
Re: convert 40 HP Merc to 20 HP

the evenrude 20hp can be converted to a 35hp by just changing the carbs.

I have a 20hp merc and a 40hp merc. but i don't think the carbs are interchangeable.

I was interested in changing the 20 to a 40.
 

overpower

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Sep 5, 2010
Messages
4
Re: convert 40 HP Merc to 20 HP

thanks kenters, so...maybe not an easy step down via carb change-out. Wonder if there is another way to step down HP though...
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: convert 40 HP Merc to 20 HP

The smart way to get a 20HP that Smoky will accept is to get a 20HP outboard.
 

overpower

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Joined
Sep 5, 2010
Messages
4
Re: convert 40 HP Merc to 20 HP

sure JB - idea though is to use what I have VS spending $2500 for same boat. Alternate really is to sell this rig & buy one with a 20 HP - that would be a shame though as it's a great set-up - just overpowered..
 
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