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Orifice sizes 1976 Evinrude 135 HP 135643D

J

JohnsrudeV4's

Member
Need to find out the best orifice combination. This motor has .030 over pistons/rings on cylinders #1 and #2. Standard on #3 and #4. Compression is 120lbs. on each cylinder(give or take 2lbs). When I "acquired" it, the float bowls had #69C plugs and #30 orifices. The threads on one side of the carb that holds the orifice screw plug was stripped and pieces of the loose threads blocked the orifice. I found the correct carb and ordered the original #30 orifices and #61C plugs. Is there a more suitable combination for a motor with 2 oversized cylinders? I saw an old post discussing #31 orifices as an option. This motor is just about ready to run, but I don't need to screw up this thing. I have another question, but that'll be on a separate thread. Additionally, I found an easy way to make water diverters that fit great.
 
1976 135hp Evinrude/Johnson

High Speed Jet - #320661 - .061 - Marked on side as 61C

Slow Speed Jet - #317473 - .030 - Marked on face as 30
 
Keep an eye on the spark plug color if they come out powdery white your running too lean the plugs should all be a nice toasty brown on the center electrode insulators.
 
Thanks for your reply. Plugs do help tell the story on the motor. It's been "a project" for over a year, but getting close to starting it. What I've done, I believe it's been done right. My biggest concern is what I may overlook! We'll see.
 
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