Mercury outboard mechanic needed

I know this is not about tractors but I need some help from a Mercury outboard mechanic. I have asked on several outboard sites with no results.

I have a 1973 model 200 (20hp) serial #3540395
It is pull start and has electronic ignition now.
I want to convert it to electric start with a battery charging system.

I know some of the parts are NLA but that does not bother me. I am use to finding NOS parts with all these old things I work on.

The electric start is easy because I already have the flywheel with a ring gear. I know I will need a starter and a solenoid for this.

What I am having trouble with is the battery charging. I have been looking threw 3 differant parts diagrams (group 14; 15 and 16) that go with this motor and they list several stators. They also list a rectifier on one diagram and a voltage regulator on a differant diagram.
Can someone help me understand this and walk me threw what parts I may need to change or add to make this work.

I will give you a link to a parts diagram page if that will help you help me.
Thanks for the help.
John
MERC 200 PARTS

The early 70's 20 hp could have either points type ignition ( and a short to spark points ignition at that), and as it went into the mid 70's a "Thunderbolt" Capacitive Discharge ignition.

That being said I would suppose if you found the exact model as you currently own, swapping it out should be a somewhat straight forward project.

Now envision that during the period from the sixties through the eighties they may have used basically the same block for a multitude of models and sizes with a few mounting tabs, bore size, or other incidentals changed around a bit. That might allow a person to mix and match parts pieces from who knows what to make a motor to use or sell. It's got to be close to 40 years now.

If you have a serial number, and it is applicable to the unit you have onhand, use it and buy what you need new. If you are just trying to piece/part it together from used parts "said to be from" this or that, good luck.

I don't think any of them came with a regulator. Many of theese smaller motors only had an ac output to run lights. To covert to DC a (less than) $10 rectifier from radio shack will work for that.

Don't expect more than a few amps at speed and nearly no output at idle, or trolling speeds.

Unregulated, as they are, or were, they can raise battery and system voltages into the 18+ volt range at cruise.

Now let me impart a bit of personal insight from a 1975-76 model I owned and used for a year or so.

If the CDI is weak, or eradic change it with new (about $300) If it's points type ignition and all burnt up looking it may be normal.

Mine took well over 7 "big man two hand" pulls to get it fired off cold, but would pop right off with half a pull when warmed. This is only with the motor attached to boat and operator in the motor starting position. If hung from a barrel or tried to start on a stand, the lack of support meant a brisk pull was not available and starting would be problematic.

Another issue with these motors is that as the lower unit is replaced, such as after an impeller change, and the nut tightened above the prop, it would pull through the casting leaving a large area for exhaust gasses to enter the prop wash and cavitate every time it come close to planing out.


I understand the actual starter motors for those are somewhat rare to find used.

So all in all I would say unless you find your exact motor with electric start to swap out parts from, forget it.

And if you expect it to run much more than a light bulb or two from the charging system, forget that one too.

I loved my 20hp Merc. I put on a 9" pitch prop, and spun it fast and easy. well over 20mph on a 14'er with my lardass aboard and a passenger too.

When you use a stator you're getting AC voltage from that and you need a rectifier to convert the AC voltage to DC voltage. I don't have a wiring diagram for outboard engines, but here's one used in garden tractors. Hal

Check here:
Untitled URL Link

Thanks for the help.
This motor is a 1973 and that makes it the first year of the electronic ignition so no points.
The motor runs well and starts with 3 pulls or less hot or cold.
I have it on a 14x48 flat boat and fully loaded down with two people it cruises at 21 mph. Plenty fast enough in a flat boat.

I wanted to add some kind of charging system so I could run some small running lights and maybe one spot light all of them would be 12V. Several times a year we may go camping and fishing for 2 or 3 days at a time. This does not allow me access to electricity so charging a battery is a problem.
I have thought about just putting a very small gas generator (1000W) in the boat to use in a emergency or to charge my trolling motor battery if it goes low. The more I look into this I am finding this may be the cheapest and best option.

The electric start is another issue and I still think I can add it with no problems. I have found 1 of the 2 mounting brackets for the starter in NOS parts bins and the other one can be made easily from some thin aluminum. I have seen the starter come up on eBay before but just was not the right timing for me. I will find one though.

Thanks for your help
John

Hi John,

I really like trolling for fish and use a 44lb trust Minkota trolling motor on a 12ftx5ft AL boat with about 700lbs load weight not including the boat, 2 people & puppy plus related and I get 9hrs easy out of a 105ahr 12v deep cycle battery while continuous trolling.

I really like the piece and quite of no gas motors running even tho I have a 8hp gas engine with me.

What you could do is use two 6v T-105 Trojan 225ahr battery's, 68lbs each and about $75eh with a US-64w unbreakable PV (solar panel), about $325 delivered.

Or you could buy two 105ahr 12v deep cycle battery's, about $75eh, and charge one that day while using one and just trade them out.

I've been 100% solar the past 8yrs of campimg and use my RV like I use my home. I don't skimp just because were camping

T_Bone

Thank you very much T-Bone.
That is just what I need. Someone that thinks out of the box and finds a solution to the problem I never considered.
Can you reply or send me a email on how solar works and what all I would need when you get time.

If you do not still have my address let me know and I will send you one you can reply to.

email sent

Well your email came back undelivered to your yahoo box

send me a email

T_Bone

sent you a email
thanks