My 20hp 1988 Johnson Upgraded To 35hp

hi guys uh here to show you my 1988 johnson 20 horsepower short shaft outboard that i converted to a 35 horsepower yes it's totally possible all you need to do is take the carbon intake off of a 35 an earlier 35 or mid 80s 35 put it on this put it on a 20 okay you could you have to advance the timing as well the final timing and i'm here to show you how this 20 horsepower that's been juiced up to 35 horsepower goes on my boat so if you notice here too this used to be a primer motor okay i'm using the old-school choke carburetor okay the choke butterfly the choke rod fits perfectly in the exact hole that your primer would initial would actually sit in see and it's got full function of the choke so it's actually drilled from the factory in the right spot so anyways we're gonna start this up and show you how this 20 35 horsepower johnson runs and uh we're on a 12 foot inflatable right now going back to neutral i'm gonna shut it off i just did uh i clocked it with my phone i uh saved a screenshot i made 34 miles per hour my 20 would never ever do 34 miles per hour i was in the low 20s with it again it's a 1988 20 horsepower block with a 35 horsepower intake and carburetor and bypass cover i'm gonna bring the boat out and show you what i've done so you can have a look and see where things are okay anyways i'm gonna say gopro stop recording guys back to you on my uh 20 to 35 horsepower conversion i'm just gonna show you what i've done here anyways i'm gonna pull the hood off it's a 1988 evinrude 20 horsepower block i've got here okay added the bypass plate from the 35 horsepower okay the intake manifold from the 35 horsepower and the carburetor the intake manifolds got a bit of a longer runner than the 30 horsepower carburetor you can see it's right here it's about a quarter inch thicker here okay which allows more fuel into the engine also there's a 5 16 fuel line instead of a 1 8 that normally is set up with a 30 horsepower motor okay i use my test base at for as a well i took apart a 35 horsepower 1981 motor okay and i checked it and compared it and did all the measurements the domes in the head are exactly the same the uh spore and the stroke is exactly the same as a 35 and a 20 horsepower motor what else can i say the read plate i measured the pedals in the read plate now we're talking about a 1981 35 horsepower that i use as a comparison and i use the carburetor off of the 35 now another thing that you will notice here is that the choke lever is here this came with the older model 35 horsepower this motor was originally a primer motor which means that there was a primer uh pump in here well i took that out okay and you'll see that the choke fits perfectly in the exact same spot that the primer would fit okay here's the choke you see how nicely that works so anyways uh to sum it up i added electric start it's a well i was running like a 35 i had a true 35 on my boat two years ago i made 35 miles an hour with a stainless steel prop this with this motor the way it's set up i made 34 miles per hour with an aluminum prop okay which is really really really good starts easy runs great okay and it's got lots and lots and lots of power okay like it's actually quite scary and just to i'll show you right there uh the air box is off in 1977 35 horsepower okay so that's about it it wraps it up guys and uh that's how i did it and you saw the proof it goes like stink anyways i all i have to say about that is uh gopro stop recording

Channel: John S.

Views: 34,979

Rating: 4.8648648 out of 5

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Id: IjIoSgSq0g4

Length: 5min 51sec (351 seconds)

Published: Fri Aug 28 2020