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1956 7520 Evinrude 7.5HP Impeller questions

I agree just stuff some rags in the cylinders and use a fine flat file and knock off any high spots on the block careful not to gouge it. Just us light pressure toward the center of the file. Once you get it running a decarb with seafoam will clean the pistons and rings up good.
 
Thats what I like to hear. I don't have any experience with engines like these, so it's a bit of a relief to hear it "looks okay" from folks that know.
With that being said. Kim, you said to decarb with seafoam. I've used seafoam in a vehicle before but never a small engine. How would I go about doing this? Just through the gas? If there's a sticky I'll try to locate it.
I've got a buddy who is lending me a torque wrench that will go low enough for the head. And should I be putting any sort of sealant on the gasket as well? Or just dry?
And just out of curiosity, why would the lower cylinder be burning more oil? Would that be something to do with the reed? Is it a problem even?
I'm really new to 2strokes. So please bear with me as I ask questions.
Thanks again, I appreciate the help.
 
Get a can of seafoam spray its best out on the water. Bring the engine up to normal temp and spray it into the carb at high idle speed until it starts smoking real good and quickly shut it down. Wait 1/2 an hour then point it toward the big part of the lake and run it WOT until it stops smoking and run it hard for a bit. Then take it back to idle speed in forward gear and final the slow speed needle adjustment.
 
Torque the head down slowly to spec and do not put anything on the head gasket. It could be a few things but once you get it running good just monitor the spark plugs. They should both be the same color a nice toasty brown on the insulators for the center electrode. Your fuel mix should be 16:1 I believe, a poorly running motor will carbon up rather quick. If you do alot of trolling be sure and open it up WOT regularly to blow out the cobwebs.
 
Great advice except I would not suggest that oil to gas ratio. Originally in the 50's and through the early 60's, 2 stroke oils were in their infancy and 4 stroke oils were widely recommended and accepted at ratios of 16:1. These "crankcase" oils were fine quality to be run as a lube oil, however not engineered to burn completely without deposits, like in the case of 2 stroke applications. Motor manufacturers had to suggest richer ratios because they had no way to ensure motor protection because oils were poor for 2 stroke applications. Through the 60's, better 2 stroke oils were developed and ratios were leaned up. Motors began to incorporate bearings and not bushings for the crankshafts and rods. OMC made substantial changes from 1964 to 1965. Safe ratios were bumped up to 48:1 on high quality 2 stroke oils. As oils evolved through the 70's, a major breakthrough came with a fully synthetic 2 stroke lubricant created by Al Amatuzio and his company called "Amzoil". Pennzoil sued him and he was forced to respell his companies name to Amsoil. Being a personal friend of my Dad's, Al offered us to further test his synthetic 2 stroke formula. This was advertised to perform flawlessly @ 100:1 in water cooled motors with crankshaft and rod bearings. We have still a few of the "bushing" outboards around and none have suffered any harm with Amsoil mixed at 2 to 2.5 oz per gallon. I'm talking about 2 1/2's, 3's, 5's, 5 1/2's, 7 1/2's, 10's, 14's, 15's, 16's, and 18's. They are all here in my possession and all running perfectly. These motors have been run at all speeds and many used for freighting in the Ontario wilderness. That means WOT for hours at the ratio mentioned above (50 to 64:1). I have tested these ratios, but not as extensively, on Mercury outboards as well. I did have a failure on my 1957 Mark 30, but I was running 40:1 petro base 2 stroke and not Amsoil. That was in about 1978 and I have the motor here but never dug into it yet. It never made any bad sounds but just seemed do drop off in power, so I shut down. Could have been a water pump failure too, it still cranks over with no fire. As for "newer" OMC's, I mix Amsoil @ 80 to 100:1, based on how they will be used.....mostly trolling, (100:1), or mostly WOT, (80:1). 100:1 OMC's were developed in the early 80's and engineered to run @ 100:1 on all oils including certain petro based 2 stroke. No changes were made to the bearing designs, yet leaner ratios were suggested......Why??? Because oils had improved dramatically and OMC had determined that 50:1 was no longer required. The big mistake was the fuel tank auto injection system which often plugged up from contamination or dangerously leaned out mixtures when used in very cold conditions. Many 100:1 outboards were destroyed because of this, I have a few of these parts motors around too. Early VRO's are destroyed by ethanol and the "alcohol resistant" versions are a modest improvement at best.
Yes, talking oil ratios.....I have plenty to say, but its all from hands on experience, not hearsay. Take care, Tim
 
Alright. So I put the new gasket in. I put it in dry and tested the compression. I hauled on it hard and fast, got up to 68psi on both cylinders.
I looked into the fuel ratio a lot when I first acquired the motor. Determined 24:1.
It's getting a little chilly up here and will be for a couple days, so I'm hoping I can fill a barrel on Sunday to get her running.
I won't be able to get it on the water to use the seafoam mainly as its all still ice. So I'll seafoam it when I take it to BC for May long weekend.
Thats assuming I can get it running right.
Thanks for all the advice. I am taking it all into account.
 
So I was able to get the motor out yesterday. Seemed to run great.
Originally I was able to go 12kmh then it would slow down to 8-9. Now it sits at a constant 10kmh fully loaded. And I didn't change the angle of the motor (sorta forgot) so it was trying to push the front of the boat up a bit. I feel that was robbing a bit of power. Ran for about 40mins straight. Not constant full speed, but I never shut it off.
So just in case anyone uses this info. Here is a list of what I replaced and did.
-Spark plugs, gapped and a dab of dielectric grease in the boot.
-Put all new gaskets in the carb. Set knobs as per original instruction book.
-Leg oil and greased moving parts etc. (Basic maintenance)
-Coils
At this point engine still slowed down after hot.
-Head gasket
-Condensers
-Seafoam
Engine now seems to run fine.
Was able to smooth out high speed and low speed adjustments.

Seems I have a perfectly working 1956 Evinrude Fleetwin engine.
Future plans are to do a complete rebuild. But for now, I'm going to enjoy what I have.

Thank you all for the help and advice. I appreciate it all very much.
 
So another update:
Engine is still running great.
Still using 24:1 mix ratio
I had it out for a day last month and had it out last Saturday and really gave it a workout. Went across Wabamun lake here in Alberta. Took a while to boat across but she ran top notch the whole time.
Had a full boat both times. Around 700lbs of cargo and people in the 14' aluminum.
Actually picking up a new boat (used, new to me) on Saturday and going to fabricate a mount for it to go beside the 50hp. Should make a decent backup/trolling motor when I'm not using my electric.
Still quite the head turner.

Still on my list is a complete rebuild. But that's down the road for sure. Maybe a winter project.
 
The sintered metallic fuel filter located in the glass float bowl under the carburetor is often a cause of fuel starvation and subsequent loss of power on these earlier motors. Back flushing the element with carb cleaner may solve the lack of power problem.
 
bobbyc said:
The sintered metallic fuel filter located in the glass float bowl under the carburetor is often a cause of fuel starvation and subsequent loss of power on these earlier motors. Back flushing the element with carb cleaner may solve the lack of power problem.
Click to expand...

These type filters are best cleaned when "shellac" has slowed fuel flow, by soaking in acetone overnight, then compressed air.
 
Thanks for the suggestions on the metal filter. I did clean it when I had the carb apart while putting new seals in it. I had it out last September and same old story. Runs top at about 12km/h then after 20 mins or so it slows down. But, runs great other than that. Shes in storage right now, So after it warms up Ill pull the bowl and give the filter a good soak and clean, cant hurt.
Thanks again everyone, Happy motoring!
 
I am guessing it is those rubber pucks just above the water intake? I don't see how that would affect speed. But I'm open to suggestions.
 
Totally wrong.------------The shock absorber is found below the water pump and inside the gearcase.-----------If the spring breaks the unit will expand and bind up the motor.---------------I am not saying it is but I am not there to listen to your motor.---Touch your motor or see your motor.
 
racerone said:
Totally wrong.------------The shock absorber is found below the water pump and inside the gearcase.-----------If the spring breaks the unit will expand and bind up the motor.---------------I am not saying it is but I am not there to listen to your motor.---Touch your motor or see your motor.
Click to expand...
ah I see. Well I'll have to take a look inside this spring and see. Thanks for the suggestion.
 
DarrenJH said:
ah I see. Well I'll have to take a look inside this spring and see. Thanks for the suggestion.
Click to expand...
Hey, brother.....how is the 7.5? Doubt if its the spring, very rare to fail. Is it still slowing down? Just got a 2014 150 Yamaha in for repair. Overheat.....what a mess, somebody else took it apart. In 1956 life was good, brother.
 
timguy said:
Hey, brother.....how is the 7.5? Doubt if its the spring, very rare to fail. Is it still slowing down? Just got a 2014 150 Yamaha in for repair. Overheat.....what a mess, somebody else took it apart. In 1956 life was good, brother.
Click to expand...
Hey Tim.
Its brutal getting something to work on that someone else tried to fix. I get that often at work. Makes for a real headache. 1956, I was born in the wrong time. I miss the simple days that I didnt even have.
The Rude is great. Just did a tune up of the wires and breakers. Ran it in the test barrel and seems good and strong. Wont know for sure till I get her out. Next fishing trip is in June. Heading up the mountains again. I never did get into the leg to have a look at the spring. I looked at the part from my parts motor and seems like something that would be pretty noticeable if it broke. So I assumed it wasnt that.
I did replace the filter element in the bowl this time rather than just cleaning it. Ill see how that works. Also new plugs.
I really want to get into the internals of her, but still a little gun shy about that. Every screw I turn Im terrified Ill break. One day Ill get passed that. But for now, Ill let her swim.
Take care Tim, Good luck with the 150!
 
You might want to soap up the surface components/gasket/bolts on your fuel tank when it is running, maybe there is a pressure leak causing fuel starvation at higher speeds??? Or try your spare tank, if you have one. Sounds like a fuel supply problem. When you go up in the mountain lakes, the air/fuel mixture will be different. Nice thing about the older motors is that both the high and low speeds are "tweekable". Take care, good luck needed 4 sure. Looks like the guy ran it out of the water and started the water pump "meltdown", then headed across the lake with no observation of the pee hole.....wonder why it didn't shut down with high heat sensor/warning??????Electronics....... I guess are not perfect.
 
I'll have a look at the tank.
After I disconnect after each time on the water, I turn the cap to let the pressure out, there's a lot in there. I'll check for air leaks when I'm out. Wouldn't a fuel problem cause a stutter or chocking noises? Seems weird that it just looses some power without hesitation or bogging etc. Just a smooth, clean transition.
Now that I've changed the filter element, maybe I'll notice a difference. I hope I do anyway.
Could a lighter weight oil be used in the gear housing? I'll have to check what I'm using now, the manual said 90w I'm pretty sure. I wonder if maybe I could use a little thinner and still be safe??? Maybe it'll gain a little more power? Maybe the cold water is making it a little too thick and she can't turn as fast?
This makes me curious.

Electronics, partly to blame on this one. Buddy shouldn't have relied on them. I hate electronics. Never can trust them.
Sounds like a heafty bill coming his way.
 
Yes, I agree with John. I run the older outboards late and in icy water in Ontario, the gearcase friction will be little affected by viscosity. Sounds like your fuel tank is tight, however perhaps the filter screen is partially blocked. You can check that by trying to siphon out some gas, just take the fitting off at the motor end of the hose and put a small 3/16" tube, (preferably bent), into the AIR side of the siamesed hose. Blow into the tube and see if you can get a siphon going by holding the end of your gas line a few feet below the level of the tank. If flow seems adequate to supply about 6-8 oz. per minute, then you should be good and won't have to clean that very fine steel screen at the bottom of your pickup tube. Simple test, good luck.

Yes the Yamaha is a mess, but brilliant engineering non the less. Probably the #1 outboard now in the US.
 
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