9
votes
Spark plug working fine in free air, but hard miss in engine
The current follows the least resistance. On a spark plug the current jumps between the gap in the electrodes. When the plug is out of the cylinder the easiest path is between the electrodes. But when ...
- 3,440
3
votes
Accepted
Rusted spark plug well/mating surface - is this a concern?
You could cut the threaded part off an old spark plug, knock out the ceramic, roughen up inside the hole, and fill the hole where the ceramic was with something like chemical metal. This can be ...
- 25.5k
2
votes
Spark plug working fine in free air, but hard miss in engine
Air is an insulator until you exceed the breakdown voltage, then it starts conducting and you get a spark.
If an insulator inside the plug breaks down at a lower voltage than at the spark gap, then it ...
- 121
1
vote
Where is model number on Yamaha 9.9 4-stroke outboard motor?
The silver tag on the transom mount, visible in the photo, is likely a stamped metal tag with your serial number. The tag should either mention the model, or the model will be encoded into the serial....
- 133
1
vote
Where is model number on Yamaha 9.9 4-stroke outboard motor?
According to the manual, the ID plate with model number, model name and serial number is located here:
The model number is in the upper left corner of this plate, the corner that looks like it's ...
- 8,548
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