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50 HP Evinrude Sizzler 1974 timing problems

havelb

New member
" This engine will not idle un

" This engine will not idle unless mag is advanced 11deg verses 4 deg per the specs when the cam contacts the carb linkage. All electrical checks out perfect, as does the fuel/carbs. Even the idle speed adj screw is far away from the stop. The flywheel looks good as does the key. Is there something unusual about Sizzler models where the timing is different? stuck on this one. Bernie "
 
"Havelb.... You say that "

"Havelb.... You say that "the engine will not idle" at 4° where the carb roller should be lined up dead center with the scribe mark on the cam.

What does the engine do.... Does it simply slow down, die out to a stop, or does it spit back through the carbs (sounds like a mild backfire), or does the rpms run up and down without changing the throttle setting ?

I'm assuming that your compression is okay and that you have a spark that will jump a 7/16" gap on both cyls with the s/plugs out. Are the carbs clean?

Give us a little more detail on this problem.

Joe
"
 
" Joe, I sent you a direct E-m

" Joe, I sent you a direct E-mail, hope it went thru. Call me collect, 810-987-6630. Compression 135psi each cyl, spark jumps 1/2" gap-nice blue color, no back spitting thru reeds. Engine runs very cold,will pull thermostat & test. Suspect dealer did poor job on carb rebuilds. Told owner to go fishing with it today, and we'll resume diagnostics friday. Engine may "condense" fuel from "severe cold running". Bernie "
 
"Havelb..... Taking into consi

"Havelb..... Taking into consideration that a dealership had their mechanic do the carburetor rebuilds (2), I suggest you take it back there and insist that they redo the job properly. However, should you for some reason wish to avoid that route, I suggest that you do this:

Both of those carbs have a slow speed adjustable needle valve at the top portion of the carbs. Just inside the casting of each carb where the valve enters is a nylon retainer/bushing. This bushing is designed to grip the valve and keep it from turning due to vibration.

The bushing should be "RED" in color. For reference, the OMC part number is 315232. In the past, OMC made two other color bushing which were "BLACK" and the other a sort of "CLEAR/WHITE". The only one that is suitable is the "RED" bushing!

If the above bushing is okay, gently turn both valves in until they seat, then back them out one and one half (1 1/2) turns.

Start the engine and set the rpms to where the engine will stay running. Now, in segments of 1/8 turns, and waiting between turns for the engine to respond, start turning the top valve in. As the rpms increase, re-adjust the idle speed just to a point where the engine stays running (not racing wildly). You'll reach a point whereas the engine will either start to die out or will spit back. At this point, back out the valve approx 1/4 turn. At some point within that 1/4 turn, you will find the smoothest rpm setting.

Repeat the above proceedure with the bottom carb. Hopefully the dealer made a error with the carb adjustments or the red bushings are missing, something of that nature. Let us know if the above cures your problem.

Joe
"
 
Re: "Havelb..... Taking into consi

I have a same engine and same problem as you do, had it in a shop the guy fixed it , it run so nice and smoth took it to the lake it starts and than dies
wouldn't keep running for nothing. good luck
 
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