Throttle Control Question

[Flying Dutchman]

I have just picked up an old low hours 25HP Evinrude E25RCEM for my Achilles Dingy. No manual of coarse.
Engine runs reasonable fine with new plugs. Starts okay etc.
The throttle handle consists of throttle with an adjustable (CW or CCW) smaller knob (about 1" long) and then the red safety shut-off knob on the end.

What is this smaller hand adjustable knob for? It does not tighten up the throttle grip, it does not in/de-crease the rpms.

What is the best spark plug to use in this engine and what is oil to gas ratio mixture. 50:1 really smokes?

Thanks in advance for all your answers.

 

[jtexas]

Re: Throttle Control Question

welcome to the forum!

factory shop manual available at kencook.com would be best, seloc repair manual is not too bad, they have 'em here at iboats

sorry I'm not sure about the knob on the tiller, you can find online schematics for your engine at:
http://epc.brp.com/default.aspx?brands=ej&lang=E
you have a 1989 model.

Use only Champion QL77JC4 gapped at .030

50:1 is correct, smoking is normal, but if you think it smokes too much, try a decarb: http://forums.iboats.com/showthread.php?t=158076

Actually, a decarb would be a good idea anyway. And a water pump impeller change if you don't know when it was last done - ought to be done ever couple years. Change lower unit oil annually. I'd do a compression test, so you'll have a baseline for future diagnostics.

 

[tashasdaddy]

Re: Throttle Control Question

the knob i believe is the carb slow speed needle adjustment. went to diagram, i was wrong on this one. still trying to be perfect.

 

[wbeaton]

Re: Throttle Control Question

I use the other recommended plug QL82C. It burns hotter and fouls less at troll.

Do you mean the red knob that seats against the kill switch pin? It doesn't do anything that I'm aware of.

50:1 is apparently the recommended mix for that motor. Originally it might have had a little sticker by the fuel connector that said 100:1. I've read a lot about the 50:1 vs 100:1 debate and I really think its only an issue if the motor is going into extended and/or outdoor storage. A couple years ago I bought a 1987 20 hp that has only ever had 100:1, was stored outdoors and has never been winterised (I live in Canada) and it still runs beautifully. Of course, I run 50:1 in my 1988 30hp so even I'm not sure where I stand on the issue.

A decarb and impeller couldn't hurt.

 

[tashasdaddy]

Re: Throttle Control Question

i believe the slicker it is the better. more oil better than less. 50-1 the mfrg change it several years later, back to 50-1, becuse to too many bearing problems.

 

[ezeke]

Re: Throttle Control Question

The knob on the twist grip is supposed to set the lower limit on the idle for trolling.

If you are smoking a lot with 50:1, you may be running with no thermostat, or you may be running rich and need a carburetor adjustment.

In any event, you may find that synthetic TCW-3 oils cut down on the smoke.