Questions about Yamaha

[ShoestringMariner]

Hey guys, looking at a couple of boats both with late 80’s early 90’s Yamaha outboards. One is a 90 and the other a 115.

Do I need to ground the spark plug wires to do a compression test on these motors?

I don’t know Yamaha at all except reputation is supposed to be solid.

Anything to be aware of with these particular models or era?

Thanks in advance

 

[Sea Rider]

If you're grounding a spark plug you're doing an electrical spark test not a compression one, for the latter will need a compression tester...

Happy Boating​

 

[99yam40]

best and easy way is to pull the kill switch lanyard to stop spark while doing the compression testing.
it grounds out the spark voltage so it cannot build up and jump in places it could do harm like inside the coils or other places

 

[ShoestringMariner]

best and easy way is to pull the kill switch lanyard to stop spark while doing the compression testing.
it grounds out the spark voltage so it cannot build up and jump in places it could do harm like inside the coils or other places

Yes. That’s exactly why I asked. I don’t want to damage anything.
Thank you for the help