Evinrude Johnson 2 cyl 40,48,50 & 60 HP

[ACAMS]

Does anybody here modify these motors?

I have heard several tricks, but would like to know details, maybe even send powerhead off.

Main question is would tearing the motor down and "porting" the intake and exhaust area help?

Heard there was a water crossover passage that should be blocked to release a few more HP.

I will be using an 84 model 60HP powerhead.

[Mark Poole ModVP]

I am sure someone with experience modding these engines will chime in with some details. All of the OMC 2 cyl. and 3 cyl. looper engines respond well to squaring and raising of the exhaust ports as well as shaving the head for more compression. I know on the 3 cyl. models some moderate exhaust port work and getting the compression up around 180 to 190 would made a big increase in performance. "Power Porting" the OMC loopers would make a nice increase also.

[ultrafast]

Find a set of the big bore carbs, I have some. Jet to run with out the airbox. Open up the cowl in the rear- big restriction. . Plastic reeds, cut the head. Finger porting helps. Be careful moving the exhaust ports too much. . You can kill the bottom end quick. Dry stack the exhaust and remove the can. Is it on a light boat. Go on ******************** . there are some real talented people on there. One guy has an expansion chamber set up? I will tell you though, you would be ahead to build a 3 cyl.

[moparman]

just curious as to which year and model the bigbore carbs were on ?

[thornl01]

Just find a set of 60 hp 2 cyl carbs or get 2 from a 3 cyl 70/75.

Tons of mods are available for these engines ie..... behind the liner porting.( look for sleeves/blocks w/o exhaust relief holes ( sleeves come out very easy) 20 mins @ 350 deg & sleeves will almost fall out. just look at things now, it will come to you what it needs. Find a set of early 60 hp pistons & you will see the difference. Cut head to 165-185 cranking comp. Take 2-3 deg timing out. expansion chamber on these engines WILL wake them UP !!

[ACAMS]

Me too!!!

I have several of these motors, and several 3 cyl stingers, but this is going on a 14' flat bottom jon boat and I just want 55 to 60 HP at the prop.

I will be using a 1991 40hp short shaft mid and lower with a 1984 60hp powerhead and feel I will not have much more than 40 - 50 at the prop without small mods.

I will also need it to idle and low RPM real smooth for running lines in the river, so I was hoping to not have to use aftermarket reeds.

I have a machine shop and can mill the head for extra compression and I ALWAYS run super in my motors.

Ultrafast, you got filtered ... can you PM me the link, or code it

THANKS.


EDIT .... I got ninja'ed .... If I do a little port relief will 77 Stinger 75hp carbs help me, or hurt me?

[scc82]

Why not put reeds in it. It will make it run better and much smother at low rpms. We make great reeds for that motor and almost every other 2 stroke around. I've installed literally thousands of reeds in outboards and ALL of them run smother and idle better. Courious to your reasoning behind that?

stan Carson,

[ACAMS]

Well, actually the only 2 strokes with reeds I have seen idled like a top fuel dragster ..... if you have reeds for this motor that will improve the performance and still idle good please PM me so I can order them.

[scc82]

CCMS. 800 329 2725. Call tonight or in morning and we can talk about your needs. Yes we have the reeds in stock. Cheep performance and safety for your motor. Will idle better burn less fuel accelerate harder and may even see some top end gains. We can also help you out with your other mods you are considering. Although your biggest gain in performance will likely come from proper setup. Happy to help any way I can, and merry Christmas.

Stan Carson.

[ACAMS]

Find a set of the big bore carbs, I have some. Jet to run with out the airbox. Open up the cowl in the rear- big restriction. . Plastic reeds, cut the head. Finger porting helps. Be careful moving the exhaust ports too much. . You can kill the bottom end quick. Dry stack the exhaust and remove the can. Is it on a light boat. Go on ******************** . there are some real talented people on there. One guy has an expansion chamber set up? I will tell you though, you would be ahead to build a 3 cyl.

What do you mean "Dry stack the exhaust and remove the can."

[thornl01]

When using the 48 mid, you may want to check the inner pipe (tuner) as the 48's pipe is very restrictive. Biggest thing on this engine is to NOT LUG the engine, prop it to turn on the top side. These engines like to breathe. Also, get some heat into the engine, Don't run it too cold.

[smokin'joe]

Does anybody here modify these motors?

I have heard several tricks, but would like to know details, maybe even send powerhead off.

Main question is would tearing the motor down and "porting" the intake and exhaust area help?

Heard there was a water crossover passage that should be blocked to release a few more HP.

I will be using an 84 model 60HP powerhead.

The xxx100 and xxx207 blocks/powerheads are used in 45SS class racing. These powerheads appear on motors from 40-60 hp. The 60 hp shortshaft model with small gearcase was discontinued in 1984, was used in SD and DP class racing. I have many blocks from many different hp motors and all are the same. The xxx207 block was a lost foam casting and has a slight intake restriction. So far as I know at this point, the only differences in 40-60 hp motors are high speed jets, heads and powerpacks on the ropestart commercial models. In 45SS racing modifications are not allowed, the motors can be blueprinted. The biggest gain is from resleeving, lining up the sleeves so that the intake passages in the block are not partially blocked. Second is milling and decking, very little is required to get 170-180 psi (more than that hurts performance). Here's the cheap way to do it for river racers: grind the sleeves to get rid of the intake passage blockage, get rid of all sharp edges where the gas mixture flows into the intake ports, and mill the head .065-.070", not more. On commercial tiller handle models (40, 45 hp, e.g.) the powerpack is rev-limited to 5850 RPM and must be changed. The carbs seem to be the same on all models (tuners too) but the low hp models are jetted very lean. Run 56D jets (standard in 1983 60 hp) and increase jet size with weather to keep the plugs wet (dry electrodes are a danger signal). and run Evinrude oil at 25:1. I prefer XD100 synthetic, and run 98 octane gas to avoid detonation although many 45SS drivers run pump 93 octane. Most hobby engineers ruin a powerhead by changing the port timing. I have a 1988 45 hp tiller handle shortshaft commercial model on an Allison EP-15 that I use to break in the 45SS powerheads, simply unbolt the (actually 60hp) fishing powerhead and bolt on the racing powerhead. I have available some preperly reworked Jim Booe castings (12 1/2x23) that run well if you have a 1980-83 shortshaft 60 hp model. The same props are run in SST60, but I set a different pitch distribution in that case. We break in the powerheads long and at low RPM with a thermostat and poppet valve, then remove the poppet valve and thermostat afterward. You do not want the motor to run hot. Water flow direction is reversed in the 45SS racing mid-section compared with the standard mid-section, so if you install both a thermostat and poppet valve in the former for break in yopu'll burn up the motor, no water reaches the powerhead in that case.

mccauleyandson.com

[1FASTLASER]

That's a lot of knowledge right there....and experience. I always wondered about these midrange motors

[MODIFIEDOUTBOARD]

The 60/50 Cylinder head can be milled to 45spec 0.515" deep, stock is approx 0.560" worth about 5 hp and will run on 93 octane pump gas.
You can go up on timining , the 60hp twins ran 21 deg from factory.

Carbs are 1.5" throat x 1.25" venturi same as 75 triple an sst 60. you can remove the factory air box from carbs and pick up about 200 rpms on top end with noticable loss of 3500-4000 midrange power. Tim Kurtz has velocity stacks and they will help top end if your not over proped. will need to go up a step or two on main jets. Boysen makes reeds for the 50 and 45ss.

a 45 style tuner can be made to adapt and replace inner exhaust. I would go longer than 45ss spec to not loose bottom/mid tourque.
also can re-route water in conjunction with tuner mod to feed engine from bottom up and get water to be about 140 deg F under WOT.

Bobs Machine makes a nosecone/low water pick up for the gearcase.

run more oil OMC recomended 25:1 for the 45ss.

[OMCStratos]

What rpms do you run, MODIFIEDOUTBOARD?