I just bought a boat with a 1973 Evinrude, the owner and I tried starting this motor and it took a while. It sat for 2 years and am wondering whether the Carbs are gummed up and this might be the problem. When it gets going it runs great except for the fact it takes forever. Any help would be great. And how hard are the carbs to rebuild?
If the compression and spark are good, you are probably correct. Have you ever worked on a marine 2 stroke before? Is the fuel fresh, the lines in good shape, plugs set proper and in good shape?
A factory manual would be a good investment, will help with all kinds of repairs.
The carbs are not hard to clean, but sometimes there are other things that should be checked when you install the carbs, ( link & synk).
1.) The choke wasn't working. Just had to fix the spring on the solendoid that closes the flap.
2.) Carbs were NOT sync'ed. When WOT, the top carbs were wide open, the bottom carbs were only about 1/2--2/3 open.
3.) Reset the slow jets. A lot of people told me to run it 1.5-2.0 turns out. That wasn't the case for me. My boat runs the best, idles the best, and starts the best at 0.5 turns out. In fact, it's still on the verge of being a bit rich still. Barely touch the choke, and she bogs. So, that's what I found.
4.) I cleaned the carb. Mine weren't that dirty, but I did it anyways.
I used to crank and crank on my motor to get it going. Occassionally use ether to help it get going. Now I just turn the key. Fires right up. I am amazed that a 43 year old motor can and will still run this good.
So an update. I put brand new coils on, rebuilt both carbs, link and sink, idle running around 8 to 900 rpm's. Replaced the impeller also. Took it out this last weekend and it was hard to start, when it did start it would idle fine, then putting it in gear it would die, restart die, restart pump the throttle and then it would go like a bat out of you know where. Then I shut it off for a little bit and tried to restart, crank crank 5 minutes later finally it would start. It will run wide open great, go to slow down to a crawl and it will not idle, turn it off and it will not start. I am lost, One other thing, when I rebuilt the carbs there is no High or Low adjustment screws, are the carbs fixed and non adjustable? Thanks once again. Any ideas would be great.
Also the fuel has been drained and cleaned before all this, and when I crank it over to start hot it will only start with a full choke. regardless of it being shut down for 1 minute of 20. and yes, the choke is closing on both carbs the same.
When that engine idles, the carb butterflys are closed. The engine draws fuel from the dedicated small idle passages in the upper carb body. If there is any residual dried fuel in those passages, it can restrict fuel flow at idle and cause the problems you note. These have to be cleaned mehodically with a gumout type fuel cleaner. Once you crack the throttle, even a little, the carbs will supply fuel from the high speed jets and the engine may run just fine-even at WOT. Yes, that carb has fixed jets. The idle is set by adjusting the ignition timing, not the carbs.
I have read in the book but how hard is it to adjust the ignition timing? And If the engine is in idle warm your saying if I look back the choke should be closed? is that why it wont start or is the jets clogged like you were saying? So adjusting the carbs to crank up the idle is the wrong way to go? I'm talking about the control cable in the engine where you can turn in and out. I'm guessing I did it wrong then.
At normal idle, the carb butterflys are closed, not the choke butterflys. You adjust the idle on the engine by turning the large screw on the spark advance lever. There is a large rear-facing screw on that lever. If you turn it clockwise, the idle timing will advance. You need to disconnect the throtte linkage at the engine end to optimally set the idle timing. Idle timing should set the idle rpm's to 650-750 rpm's. Set when the engine is running in forward gear, when the boat is in the lake. You can't set it on the trailer. When you reconnect the throttle cable, you may have to ajust the cable turn screw slightly so that the cable end matches up with the engine linkage bolt/pin.