1975 Johnson 50 HP 2 stroke - Maintenance questions

[gottjoe]

Hello:

I have a 1975 Johnson 50 hp 2 stroke for my boat. I had some issues running this past weekend which I believe is related to the fuel not being fresh, the spark plug being gunked up, and possibly the fuel mix ratio. At least, this is what some of my friends who have been 2 stroke motor owners tell me. I'm still a newbie at boats, but getting pretty good at getting frustrated from being one.

So here's my questions:
1) What is the correct fuel mix ratio for my year & model motor?
2) Does it matter whether I use regular or premium gas in this older model?
3) What is the best brand and type of oil to use for the mixture
4) What is the best spark plug to run in the motor, and how often should I change it out?

As an aside, does this model have an automatic choke, or do I have to pull the cover each time to give it some?

Thanks to any and all who can help! I'd love to fish in my boat, and not spend time worrying about how it's running.

 

[emoney]

Re: 1975 Johnson 50 HP 2 stroke - Maintenance questions

I know some of your answers, and since noone else has weighed in, here goes;
1) 50:1
2) Nope. But, ideally, gas without Ethanol if you can find it.
3) TCW-II (Goggle that to make sure or wait for someone else)
4) Don't know. It's wisest to order a Factory Service Manual for any marine engine. I have one at home and if noone else weighs in, I'll look it up for you.

As to the choke question, doesn't seem like you should be needing to remove the lid every time you want to start it. That's rather counter-intuitive. Does your ignition key "push in" as well as turn? I'm asking this, because of lot of outboards have the choke tied into the ignition by just pushing in the key while starting it. If not, I'm assuming you don't have a choke nob on the motor itself, so you might look into if it's just missing and needs replaced.

What kind of service has the motor had done to it? By saying "issues running" well that could be one of a couple hundred issues. The thing about boats and their motors is they don't HAVE to be frustrating if we practice the "An ounce of prevention is worth a pound of cure" theory. Spending a little time in the driveway doing maintenance can make for enjoyable outings at the lake. For example, when's the last time the water pump was serviced? Has the fuel system been maintained by cleaning/replacing fuel filter/diaphram check ont he fuel pump? You should inspect the lines all the way from the tank to the fuel pump because Ethanol in today's fuel will eat the rubber away causing problems. When was the last time the Carbs were cleaned/serviced? Another source of rough running issues. It's not rocket science, at least and you're at the right place to get advice and assistance in catching up if she needs work.

 

[gottjoe]

Re: 1975 Johnson 50 HP 2 stroke - Maintenance questions

Thank you for the replies!

The motor was completely checked over last year, and I've used it twice since. That's about all I know. That's why I take it to a shop and do not try to do it myself. Sounds like I should take it in and have it checked. Better than getting caught with a problem on the water!

Thanks again!