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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 14484
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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What spark plugs do I need for a 9.9 two stroke Mercury outboard

Resolved Question:

What spark plugs do I need for a 9.9 two stroke Mercury outboard engine, from about 1986?
Submitted: 5 years ago.
Category: Boat
Expert:  Jason replied 5 years ago.

Hello, and welcome to Justanswer. My name is XXXXX XXXXX I will be helping you today. If you need clarification on something please post back here.


Do you happen to have the engines serial number handy?

Customer: replied 5 years ago.
Customer: replied 5 years ago.
I just want details fo the spark plugs because I want to change them
Expert:  Jason replied 5 years ago.

No problems.


The older 80's units take an NGK BPZ-8H-N-10 for a plug. I wanted to run your serial number to make sure that is actually what you had though. But if your positive on the year, it will be that plug.


Post back with questions.
Good luck!




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Customer: replied 5 years ago.
What will happen if I put in the wrong plug?
Expert:  Jason replied 5 years ago.

It all depends on why the plug is wrong. Plugs come in different shapes, styles, and heat ranges. The most common mistake is a wrong heat range plug.


If you put in to cold of a plug, it's no big deal, and the spark plug fouls out prematurely

If you put in to hot of a plug, you can melt the motor down internally.



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