1972 evinrude 4hp yahtwin

[drewmitch44]

i own a 1972 4hp evinrude yahtwin and it runs a little slow than other 4hp's ive seen on 14' jon's that ive seen. I have to pull the lower unit out of the water to get it started and its real tricky to start. I have the origional manual for this motor and the carb was just recently rebuilt. it gets spark and pumps water in factive changed the impeller at the middle and at the end of the season. Im trying to get it running right for next year. It does ok for me just being a 4 hp I live in central delaware and the bigest pond in this area is around 100 acres so i dont really need anything more than a 4hp. Im ready to see what the problem is and get it ready for the next year. This is a verry clean motor thats been well taken care of and in the family its whole life. I was supprised it is a 1972.

[OBJ]

A thing or two to look at Drew....Look at the cam follower....it's the black plastic lever that sets on the top port side of the carb. These will get a pretty good groove in them and not allow the throttle plate to open a little during cold starts and also not let the throttle plate come all the way open at WOT. If it's got a groove in it, replace it. They are still available through any John/Rude dealer. PN 812312...'bout $5.After it's replaced, make sure that the hash mark on the came meets the leading edge of the cam just as the throttle plate starts to open. This is set by adjusting the cam in or out. Look for two 5/16" bolts holding the cam to the mag plate.Ever give the old girl a decarb? Might be a good idea. And take a set of compression readings.How many turns out from lightly seated is the low speed needle? Shouldn't be any more than a turn and a quarter to start and then adjust for best idle after she is up to temp.

[drewmitch44]

ok cam follower is new, came with the new carb. carb new or a remanufac.. its always lubed in the off season and the lube process is followed thats in the owners manual every year since the motor was bought. i looked in the flyweel and the ignition stuff in there looks new. dad told me he had a problem with the float in like 85 but the carb is new now since august. he neaver had it overheat on him which is from what i am to understand causes compression loss but i havent had a compression test. i i dont have any kind of tool to do this was suprised dad had the omc tool for the flywheel. where can i get parts for this motor anyways? id like to do some investigations of myself but manual says you have to replace gaskets everytime you take something off. Im pretty handy with small engines but not outboards. anyone know of a websight where there are old evinrudeparts??? any advice where to start is apreciated. also the high and low speed adjustment pins are new i reset the pins for high speed and low speed. if i remember the low is like 1 turn out and high is like almost 2 i have experimented with both and so did the shorts marina that did the carb

[Paul Moir]

Parts are easily available almost everywhere. They built that engine in one form or another from the very early 50s to the late 80s. I've got a '72 Johnson version myself.Iboats actually sells many parts, head gaskets, carb kits, water pump impellers, ignition coils and bits, etc, etc. Those are aftermarket parts. There's also dealer parts for every blessed bit of the engine. Most of those are still available. Personally though, I just cut my own gaskets rather than making a trip to the dealer or ordering.Check out compression & spark. You just need a typical automotive type compression checker (~$15 at discount tool stores). Make sure it's got a readable numbers in the 50-100psi range and that it's the type that screws into the spark plug hole, not one you hold in. You'll need 4 or 5 good pulls usually to get your reading on one of these small engines.Checking spark is easy. Just rig it up so you force the spark to jump 3/8" to the block. If you're getting 3/8" long snappy sparks off each spark lead, you're good.Low starts at 1 and 1/2 turns out, and high at 3/4 of a turn. My one sits at about 1/2 turn out once the high speed adjustment is made, and I think about 1 turn out on the low speed.The 4hp engines are based off an old 3hp design and aren't very fast even when tuned right up. As one Iboats member put it, they go half the speed of stink. But they should be easy to start. Mine never takes more than three pulls ever.

[OBJ]

I'd like to reiterate about the cam follower pick up point....If it's off the wrong way, it can make start up tuff. And I usually find it helpful to set the high speed needle first and then set the low speed needle.

[drewmitch44]

ok i just pulled the 2 plugs out and the top one is dirty like normal it has deposits of brown and basically looks like a normal plug you would pull out of any engine. The bottom one when i pulled it out it was verry much cleaner than the top one. Is this a clue for what could b wrong? it looks like the bottom one has been firing but not as much deposit build up on it. the top plug's (dirty one) gap is open just a pinch from the bottom when i checked it with my plug gap tester. when the motor runs it dosent make any unusual noises. guess i just need to get that compression tester. any input on the plug thing would be apreciated...

[drewmitch44]

also i just changed these plugs at the begining of the season and they looked both the same then as far as the deposits and what not and it had been a whyle since they were changed the plugs were the j6j's whch they havent made in years.

[drewmitch44]

just wondering does this mean that im running on only 1 cylinder? and how can i tell?

[Paul Moir]

I'll bet you you've got a cracked ignition coil. Do that spark test I mentioned. That's a fairly common fault with those engines. You'll get it to jump a spark plug gap no problem, but when you use the wide gap to simulate firing under compression, the coil arcs over instead. My 4hp had that problem before I got my hands on it. It was extremely hard to start and ran at about 1/5th the speed of stink.It's easy to check to see if the outboard is running on one cylinder. Start it up in a bucket or on a boat and pull each spark plug wire, one at a time. A weak cylinder or one that's giving you no power will not affect the way the outboard runs.Spark plug gap ought to be .030".

[drewmitch44]

how do i check if im getting a 3/8" spark? i just looked at the plugs whyle i pulled the rope to see and they both were gettin spark. i dont know how to check the distance of the spark. im not trying to be a smart *** or anything i just dont know how to do this.

[drewmitch44]

let me know and ill do it cause i have no problem replacing the ignition coil condencers and all. thas stuff looked pretty clean but i guess since they are inside the flywheel they dont have a chance to get dirty and what not..

[drewmitch44]

Paul Moir could i get your email addy you have been so much of a help to me for the last year or so man i think you are the best with these small motors!!!!

[drewmitch44]

my email addy is drewmitch44@comcast.net and id like a link to where i can get parts for this motor like the ignition parts in the flywheel and such well anything basically. it seems like that might b the problem with the spark since the top spark seems to be a lot stronger than the bottom. im just putting in the plugs i was using and even the clean plug that was in the bottom seems to spark a lot stronger when i put it in the top wire.

[BoatBuoy]

drewmitch,Make yourself something like this to check spark. Set the gap to the diameter of a 3/8" drill bit. Or, you can probably find one at your discount tool store for $8-$10. When using one of these, you watch for the spark as you pull the rope.EDIT: And yes, you're right. Paul's the man. He's helped me a lot with both my motors.

[drewmitch44]

well what do you hook the clamp too? is it the inside of the boot?

[BoatBuoy]

The plug cables snap on to the threaded studs. The clamp connects to any un-painted part of the engine, it's a ground wire. Don't connect to flywheel.

[drewmitch44]

thats a good invention ill try that tomorrow what size is the threads u used on this thing as far as the headless bolts?

[drewmitch44]

where can i get electrical parts for this motor? internet site i mean where i can order them

[OBJ]

You can get them at any local John/Rude dealer or try iboats Mega Mall. The tab is at the top of the page.

[Chinewalker]

A very clean plug can also indicate a blown head gasket, particularly if it looks steamcleaned or has water beaded up on it...- Scott

[drewmitch44]

ok i tested the spark with a tool i made that looks similar to that wood tool above. Im getting good spark in fact more than a 3/8 spark. whyle i had the plugs out i stuck my thumb over the top cylender hole and as i turned the flywheel by hand i could feel inside the cylinder pulling in and pushing out air. From what im told that is what is supposed to happen. Well on the bottom cylinder there is nothing no air trying to get in or out. this might not be the best way to test compression but i think that nothing is happening in the bottom cylinder. If thats the case is the next step to rebuild the power head and if so what parts and where do i get em?

[Paul Moir]

That's too bad. I think you can get +.030" pistons and rings fairly inexpensively from your local dealer. Perhaps you're lucky and it's just a blown head gasket or a couple stuck rings, but either way start by taking the head off.I'm putting together a 4hp teardown/reassemble project over at the shareaproject.com website. Here's a link to it (I've only just started, check back in a couple days): http://www.shareaproject.com/pages/i...i,2526,00.html

[drewmitch44]

so if thats the case should i start a new topic for rebuilding the power head?

[drewmitch44]

i just figure that man there is a new carb new coils and condencers and points new plugs new prop and new fuel screen, the motor will run on just one cylinder and everything is new why not rebuild the power head? Paul it looks like in your web sight you are tearing down the same motor just the johnson version. am i right by trying overhaul out and should i just bank on the 30 over pistons or should i just put it in the next weeks trash?

[Paul Moir]

Still working on it - there's a little more now. It's up to you. If there's something seriously wrong with the bottom cylinder, you might want to opt for an ebay powerhead. There's a '79 going for $20 presently, but if you bide your time there will definitly be more. Use these search terms:(4, 4hp) (evinrude, johnson) (powerhead, engine, block)Probably a rebore job isn't reasonable. I think you could probably get the pistons & rings for $100 or so, but then you'll need to have it bored. Probably $400 at best all told. But pull the head. Maybe it is just a blown head gasket. My 4hp had stuck rings on the bottom cyl (<50psi) and now has 100/95.