hotrod53
Chief Petty Officer
- Joined
- Oct 16, 2009
- Messages
- 508
I have a '77 Merc 500 Thunderbolt. I put new plugs in this motor when I built the boat 4 years ago, I've had them out to winterize, but apparently didn't pay much attention. I'm running NGK center fires BUHW-2 and the motor has been running trouble free. Last winter I bought new plugs and today I decided to put them in. It has been starting well, but I noticed not quite as easy this year.
When I pulled the plugs, here is what I found, and these numbers are the percent of the center electrode remaining.
#1, 100%
#2, 80%
#3, 40%
#4, 65%
I'm familiar with 2 stroke engines through my dirt bike days, but outboards, not as much.
1, how often should I be changing plugs?
2. Is the loss of center electrode normal based on the 3-4 years in the water with an average of 6-8 outings
3. How do you explain the difference in plug wear from cylinder to cylinder?
4. Do you suppose any issues based on the electrode wear?
The plugs pictured are cylinders 1-4, left to right.
When I pulled the plugs, here is what I found, and these numbers are the percent of the center electrode remaining.
#1, 100%
#2, 80%
#3, 40%
#4, 65%
I'm familiar with 2 stroke engines through my dirt bike days, but outboards, not as much.
1, how often should I be changing plugs?
2. Is the loss of center electrode normal based on the 3-4 years in the water with an average of 6-8 outings
3. How do you explain the difference in plug wear from cylinder to cylinder?
4. Do you suppose any issues based on the electrode wear?
The plugs pictured are cylinders 1-4, left to right.