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Mercury 4.5HP Project - Need Help

SkilSaw

New member
A little background first. I've always enjoyed working on anything mechanical and had great luck taking on project cars, mowers, etc, but this is my first boat motor. I bought this to fix for a small flat bottom boat I have. The previous owner has removed some parts and I realize I'm missing a few now. I registered here hoping you guys could lend me a hand, as I am way out of my league. I've attached some pics of the motor and I'm not sure what the parts missing are called so maybe you can help. The plastic throttle link has been epoxied together for now until I can get a replacement, but I am not familiar with this ignition system at all. What all can you see that I'm missing and would you happen to know where to find it? Thanks in advance for any help and please be gentle! Thanks again
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Well you picked a tough one for a project. Not that it's tough to work on, just that many of the parts have been long discontinued - that can lead to a lot of looking and long periods of waiting.

Depending on where you live and how prolific this motor was in your area you might easily find parts for it, otherwise you might be chucking many bucks to one of the few recyclers that might have what you are after.

On a positive note, it looks like most of the ignition (or all of it) is there. If the coils and condenser are fine that is a major plus. Unless you have removed some stuff you are obviously missing the "no longer available" flywheel plus it's nut and washer and the entire starter assembly, which in it's individual parts was a bit of a nightmare - finding one "whole" is what you should shoot for. Again, most of it is "no longer available" - so used market sources if you can find one.

Merc used two different carbs on this model. The earlier ones had a Tillotson and the latter a Walbro. Rather uncommon, but in this case, Merc still stocks a kit for the Tillotson but not the Walbro (that may or may not be an issue depending on the condition of the carb). Both carbs look the same (until you look close) so can't tell from your pics which you have.

Do you have the top cowl (cover/hood - pick your term) - if not you will need to find one of those as well.

Personally I would spend about 15 minutes on this motor. The first few minutes would be spent attempting to get a compression reading (a little tough lacking a flywheel, but would jury rig something). If the compression was ok I would contact Twin City Outboards with my list of "needs" and see if 1) they have the stuff and 2) how much they are trying to get for it (and it wouldn't be cheap - if they have the flywheel and starter assembly I would suspect they would be looking for somewhat over 300 bucks for it - generally 50% of the last list for new parts when they were still available - plus shipping of course).

If that was the case (cost that is) I would finish stripping the motor down, sell off whatever was usable and move on to something else. In running condition this motor is worth maybe a couple hundred bucks - somewhat less that what I estimate if would cost you fix it IF you can source the parts.

A 1970's/early 80's Johnson or Evinrude portable is decent project motor - they have great parts support. A 1986 or newer portable twin cylinder Merc is likewise a good project with decent parts support.

This model maybe not so much...
 
I should mention that I do have the flywheel, nut, and cowel. I was afraid that I was missing something else. I'm assuming this model wouldn't have points, correct? Thanks for your help! You have no idea how much it's appreciated. I enjoy little projects like this, that's the only reason I do them. Thanks again
 
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The points setup is missing. Those are great running little motors when the ignition system works, and a nightmare when it doesn't.

Do a compression test before going any further.

Jeff
 
if you find the points and get it close to running ,replace the water line someone installed on carb with a line made for fuel..
 
That's it--that's the maker points. They act like a switch, closing to fire the plug (the opposite of breaker points). Clean the faces, set them around .018 ", ands see if you can get spark.

Jeff
 
I received the scrap parts I bought from ebay which includes part of the insulator and a used set of points as pictured. Can someone explain how to connect the insulator please? I know the points need to be put on my motor and gapped, other than that it should just be the insulator that needs installing. Thanks you all for all the help!
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That's awesome. Again, I can't thank you enough. I'll be sure to check it when it gets here. All I got on these parts is the white plastic "housing" that goes around the insulator to the points. I assume this is the insulator, I'm not even positive about that. No spring or wire or such. I don't know anything about that. Would anyone be able to take some detailed pics? I do not have a manual at all and haven't been able to find one. Even if I did find one currently, I'd have to wait to buy it due to just starting a new job yesterday. This motor is much different than anything I've previously worked on, but I'm confident that I can eventually figure it out. You've been a great help!
 
I couldn't find anything either, but judging by diagrams ir's just a small bolt soldered to a wire as you stated before. I can give that a try. Again thank you for all the help
 
Would the bolt have to go in with the thread side facing the points or could you insert it so the threads are on the outside and just add a wire with a ring terminal?
 
I think I have every part needed and attempted to put everything together, but still no spark. I'm almost positive that I don't have all the wires in the correct spots. Any way someone could take a pic of their complete electrical wiring on one of these motors for me?
 
Well, I hooked up the green to + and wire from point insulator to negative and still no spark. I refuse to give up on a project like this, but still no spark
 
..."Disconnect the kill wire from the kill switch and see if you get spark "

Noooo! This ignition system works assbackwards from the usual set up: you OPEN the circuit to kill the motor, and GROUND the circuit to run it.

Jeff
 
The wire colors are going to be different as the factory wiring was partially missing or bad so I'm using wire I have lying around, but this helps a lot! I'll be trying this as soon as possible!
 
The wire colors are going to be different as the factory wiring was partially missing or bad so I'm using wire I have lying around, but this helps a lot! I'll be trying this as soon as possible!

Did you sort this, I have come across a simiilar motor and understand you may be very close to success, if you havent already, I understand the case has a switch on the port side of the motor that seeks to assure that the cover is in place before allowing the ingnition to be connected, the switch on mine seems to be intact and appears to earth the ignition in a similar fashion to the kill/switch.

I am trying to resolve that my coils and condenser are intact/working, having some flashbacks to my old 1964 Eh Holden, but that was a while back- early 1990's...
 
http://www.ebay.com/itm/MERCURY-563...ash=item1c6c93bab8:g:PekAAOSwHoFXrMhX&vxp=mtr
The wire that goes to the points goes to coil neg the white wire. The post goes through the insulator and the points spring and held tight with a nut and star washer. If you crack the insulator it needs replaced as high voltage goes through it and fires the coil when the points close. That is why the points get real burnt and pitted but work just fine as long as the gap is good. That wire and post is the first new I have ever found you may want to grab it before the seller knows what hes got. It could easily go up to $80 or more. Make sure the ground wire pigtail under the coil is making contact with good metal or just solder a wire onto it and make sure it has a good ground. I will try and find the wiring diagram online there are a couple ways to wire the kill switch depending on if the switch is NO or NC.
 
I dont know if you ever got this running but 1 thing you are missing is a fuel pump. where the water line is hooked up at , a fuel pump belongs. what did you ever figure out about wiring?which coil wire goes where? white to points?
 
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