I need some help on this problem. Engine is a stock 20HP Vanguard, horizontal shaft, Nikki 2 bbl carb, model 351447-1180-A1.
I bought it used. It would start and run.
After getting it home I pulled the spark plugs. #1 was black, smelled of gas. #2 looked good - nice light brown color.
I put a spark tester between the #1 plug wire and plug - plug was firing. But, if I pulled #1 plug wire off when the engine was at idle, the engine ran at the same rpm - no change at all. If I pulled #2 plug wire off the engine stopped.
I switched spark plugs from side to side. Same conditions applied, except the black plug changed to light brown when put in #2 cylinder.
I tested #1 magneto: 5.8K ohms.
Valves are adjusted to 0.005"
I checked the diodes in the kill wire and both are good.
The magneto is set at 0.010" from the flywheel magnet.
Carb idle mixture screws are turned out 3/4 turn.
Idle speed is 1200 rpm.
Compression is 140 psi in both cylinders
I have cleaned the carb (ultrasonic cleaner), new float needle, checked that the float does indeed float level in a container of water.
With the muffler off, I can see occasional blue flame at #1 cylinder exhaust port. Not so much at #2 exhaust.
Engine rpm wanders, some times increasing, settling back to idle.
So, I'm asking for possible solutions to my problem. I think it's ignition related. Other opinions?
I bought it used. It would start and run.
After getting it home I pulled the spark plugs. #1 was black, smelled of gas. #2 looked good - nice light brown color.
I put a spark tester between the #1 plug wire and plug - plug was firing. But, if I pulled #1 plug wire off when the engine was at idle, the engine ran at the same rpm - no change at all. If I pulled #2 plug wire off the engine stopped.
I switched spark plugs from side to side. Same conditions applied, except the black plug changed to light brown when put in #2 cylinder.
I tested #1 magneto: 5.8K ohms.
Valves are adjusted to 0.005"
I checked the diodes in the kill wire and both are good.
The magneto is set at 0.010" from the flywheel magnet.
Carb idle mixture screws are turned out 3/4 turn.
Idle speed is 1200 rpm.
Compression is 140 psi in both cylinders
I have cleaned the carb (ultrasonic cleaner), new float needle, checked that the float does indeed float level in a container of water.
With the muffler off, I can see occasional blue flame at #1 cylinder exhaust port. Not so much at #2 exhaust.
Engine rpm wanders, some times increasing, settling back to idle.
So, I'm asking for possible solutions to my problem. I think it's ignition related. Other opinions?
B&S Vanguard spark problem
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