Spark plug issue

[Powershouse]

I have a 1995 Model 25M, serial 0G264401.
The plugs that are in the engine are BP8HN-10. I ordered some fresh plugs and was looking up the gap setting and manual I found says the correct plug is B7HS-10!
So now I am wondering what the correct plug to use is. The boat seemed to run fine this past season (my first as owner) with the BP8HN-10. Could a previous owner have put the wrong plug in, or is this plug an improvement in some fashion?

 

[Powershouse]

Going down the spark plug rabbit hole I have learned that the 7 and the 8 refer to the temperature range of the spark plug and that for NGK the 7 runs hotter than the 8. When I removed the BP8HN plug it was black and oily which would seem to indicate that a hotter range plug such as the B7HS would be in order. Am I on the right track?

 

[Sea Rider]

The difference with both spark plugs is that the BP has a protuded extended tip whereas the latter is the standard tip. Use whichever one including its heat range the factory recommends going for for said motor tu run well as was designed to do. If it's a 2 stroke motor will find blackened plugs doesn't matter which plugs are in use, it's the spirit of such filthy motors...

Happy Boating​

 

[flyingscott]

There is a service bulletin for those motors. Your plugs should not be black all the time. Black plugs are indicative of a rich running motor.

 

[Sea Rider]

There is a service bulletin for those motors. Your plugs should not be black all the time. Black plugs are indicative of a rich running motor.

2 stoke spark plugs tips ends being fouled with oil which gives a darkened black color looking, not black plugs though. Use the spark plug brand and type specified by the menufacturer...

Happy Boating​

 

[flyingscott]

2 stoke spark plugs tips ends being fouled with oil which gives a darkened black color looking, not black plugs though. Use the spark plug brand and type specified by the menufacturer...

Happy Boating​

What motor did you have that them tips were blackened? Because mine all run a nice tan color.

 

[Sea Rider]

What motor did you have that them tips were blackened? Because mine all run a nice tan color.

Mine too, just used the wrong wording for fouled looking, but the nice tan looking color will turn into a much darkened tan color due to carbon build ups over run hours which is normal, some 2 stroke oil fouls tips more than others along the fuel/oil ratio used.

Happy Boating​

 

[racerone]

Thermostat is shown in parts book.-----Thermostat in place and working properly ?-----Or missing / stuck open ?

 

[Faztbullet]

Oil will not change the color of the plugs, combustion temp, oil ratio and A/F ratio determine color of plug.