1982 90 johnson 1:1 gear ratio

[magnumrapala]

Im looking to build a foot for a 90 johnson and i'd like to have the ratio in the foot to be 1:1 instaed of the usual 2:1 does anyone know where to purchase or order these gears?

 

[oldcatamount]

Re: 1982 90 johnson 1:1 gear ratio

You might try www.maxrules.com This guy has a good stock of parts and a good selection of dealers he uses. He's bailed me out a few times.

 

[Vic.S]

Re: 1982 90 johnson 1:1 gear ratio

Can you actually do this ?

Cant you achieve the same result with a prop with a different ( double) pitch

 

[Dhadley]

Re: 1982 90 johnson 1:1 gear ratio

The only reason for a 1:1 ratio is for racing. I don't remember right off what the SST 100's had for a ratio but it was either 1:1 or pretty close. Very rare gearcase though!

 

[Faztbullet]

Re: 1982 90 johnson 1:1 gear ratio

Here ya go but your going to need a special prop and a light boat(under 1000lbs)

http://cgi.ebay.com/ebaymotors/OMC-Evinru-Joh-Racing-Lower-Unit-70-80s-Speedmaster-/300474820152

 

[magnumrapala]

Re: 1982 90 johnson 1:1 gear ratio

the boat weighs about 700 lbs but ive put everything that the same year 140 has on the 90, had the ports cut, and polished the intake. ive been told by a local mechanic that i will need a left handed prop.

 

[Dhadley]

Re: 1982 90 johnson 1:1 gear ratio

The polished intake will probably hurt more than help. Yes, you'll need a left hand prop. It'll most likely be a solid hub too. Unless this is a tunnel boat it probably won't do what you think it will.

 

[Faztbullet]

Re: 1982 90 johnson 1:1 gear ratio

The polished intake will probably hurt more than help

Unless this is a tunnel boat it probably won't do what you think it will

Agree 110%.......
There are a lot of things you got to do to make a crossflow make some hp,was the 90 hp blocks porting raised? Was the pistons and block cut? (Dhadley knows what I am talking about) Ya got stuffers in intake? Was reed blocks cut? Was exhaust megaphone played with? Etc,etc,etc,etc....

 

[ONERCBOATER]

Re: 1982 90 johnson 1:1 gear ratio

from my experience with 2 strokes (all engines in general actually) you can smooth the intake, and smooth the overall path air takes through the engine thereby reducing pumping losses, but you want to leave a satin finish or rougher. The reason as i understand it is that a mirror smooth finish (or any too smooth finish for that matter) will cause the fuel to bead and run down it rather than spreading out and vapping off, the large beads of fuel do not burn as well or completely and you get less power out of the charge. My own two cents to that is that fuel beads would also make for an aerodynamically rougher finish.
I have tried it both ways with smaller piston ported engines and the results were surprising.

That said I would really like to see pics of boat at speed when you finish this project.

Sean

 

[Faztbullet]

Re: 1982 90 johnson 1:1 gear ratio

you can smooth the intake, and smooth the overall path air takes through the engine thereby reducing pumping losses

True in a 4 stroke engine as the cylinder pulls a vacuum on downstoke to allow outside atmosphere to fill cylinder. A 2 stroke the crankcase fills from the the vacuum on upstroke and is pushed into cylinder on the downstroke,you want the mixture "tumbling".Thats why a 2 stroke only burns about 60-70% of fuel it uses as the rest is blown out exhaust port, thats why a test tank is always so nasty...

 

[ONERCBOATER]

Re: 1982 90 johnson 1:1 gear ratio

yes and the only way to capture a percentage of the wasted fuel air mix with a 2 stroke that leaves the cylinder is a tuned pipe, unfortunately they are noisy and don't look so hot on outboards (my opinion) and they really dont leave enough room to put an efficient tuned pipe in the exhaust housing (i know i worked on it for a while trying to figure out how to do it so it wouldnt show)

Anyhow good luck.

Sean

 

[magnumrapala]

Re: 1982 90 johnson 1:1 gear ratio

As it turns out the boat will only take 50 to 51 mph before i cant hold on beacause it chime walks too bad so ive either got to spend time learning to drive it or get some glass work done. I have not gotten a new gear case but i am looking for some pre '75 cyl heads and the intake filler blocks. just got a tach in it and a 23 pitch silver streak prop so ill post after my next run how it all goes