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1985 25 Horse Johnson

B

Bronco 74

New member
New to this forum stuff. Bare with me. I have an old motor that runs great at mid range and sometimes at top end. I have cleaned all I know to clean on the motor. All hoses have been replaced as well as a good carb cleaning. New plugs twice within 3 weeks. Running 50:1 in the tank
 
So it won't run properly at low speed? "Sometimes" running good at full throttle? How well does it start? Compression test and spark test for starters on this one. A 25 should have 110 psi but will run pretty good at 75 or 80. Spark should jump 7/16" with plugs out and the color should be a blue/white with a nice crackle. You can make a simple tester by 2 nails through a board, then under the board put a 10" piece of plug wire, (solid core), to one nail. I use any jumper wire to go to engine ground and the other nail. You can control the gap by the position of the alligator clip on the ground nail. Clamp the board somewhere nice on the motor so it wont fall, then just move your plug tester to the other wire on your outboard for cylinder 2.
 
timguy said:
So it won't run properly at low speed? "Sometimes" running good at full throttle? How well does it start? Compression test and spark test for starters on this one. A 25 should have 110 psi but will run pretty good at 75 or 80. Spark should jump 7/16" with plugs out and the color should be a blue/white with a nice crackle. You can make a simple tester by 2 nails through a board, then under the board put a 10" piece of plug wire, (solid core), to one nail. I use any jumper wire to go to engine ground and the other nail. You can control the gap by the position of the alligator clip on the ground nail. Clamp the board somewhere nice on the motor so it wont fall, then just move your plug tester to the other wire on your outboard for cylinder 2.
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Low end runs good.
 
Check for spark when that happens. Your switch box could be dropping a cylinder. Brand new that motor had 120 PSi you want it to be above 100 on the the 32 cid block.
 
flyingscott said:
Check for spark when that happens. Your switch box could be dropping a cylinder. Brand new that motor had 120 PSi you want it to be above 100 on the the 32 cid block.
Click to expand...
Plenty of fire. Just wondering if I have a bad staytor on the thing. Gonna rebuild the carb again tomorrow
 
Stators really don't act that way, besides we need to determine whether its a spark or fuel issue. You should eliminate things systematically.
 
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