1989 Johnson - need more speed

[goof008]

Hi guys. I am new here and just bought a new to me 1989 Lund Tyee 1750 with a Johnson 90 on it. I was expecting a little more out of it. I'm new to the world of outboards. I know that I can change the prop to get better top end, but the hole shot will be slower, etc.

I've read a lot of posts on here about the 90 hp upgrades. Basically, without reporting the thing, can I get carbs and heads from a 115 and improve the 90 that I have? If I can swap parts, great...if not, I can live with it.

The boat is about 1200lbs, I believe w/o the engine. 2 passengers were in it totaling about 300 lbs. Top speed was about 33-34 mph. I don't have the prop data or the WOT, but it did seem to go a little faster (.5 mph) when I backed off the throttle just a touch. If I remember correctly, the tach was reading 5000-5500 rpm.

Any help would be great, there seems to be a lot of very informed people here!

Thanks,
Jeff

 

[Chinewalker]

Re: 1989 Johnson - need more speed

The 115 uses different porting, so simply bolting on 115 carbs won't gain you much. Best to find a 115 if that's what you want.

Ideally you'd like to have your RPM peaking around 5600-5800 RPM or so. If you're not breaking 5500 you may have a little room to work with as far as propping goes.