Torque spec for outboard plugs?

[Wish-I-Were-Fishn]

Motor is a 50hp Yamaha 2 stroke. Anyone know the spark plug torque?

[Surface Tension]

Not too tight and not too loose.

There are basically two types of plugs. Flat seat w/washer and conical seat.

Yours NGK (B8HS) has a flat seat with washer. If its a new plug you'll feel when the washer comes in contact with the head.

Once there you'll begin to tighten the plug and compress the washer till it is seated. That is usually 1/2 to 3/4 turn.

If your putting a used plug in you'll know that once contact is made your down to 1/4 turn.

The conical seated plugs have no washer and once you make contact the it'll be less then 1/4 turn.

There are specs on torque but as long as you know what it should feel like when the plug is seated properly you'll be much more accurate then a torque wrench. For one a thread with some rust or dirt will have more resistance then then one that is clean.

Thread size matters as well, the small dia plug the less torque is to seat it.

As long as your aware when the contact is made with the flat seated w/washer or conical plug then you'll know when to stop.

Biggest mistake is people tightening too far. Damage to the plug or stripping out the threads will happen.

[Moose-Hunter]

Outstanding explaination Frank!!! Good job!!!

This is EXACTLY how I've been doing plugs for decades and how my Yamaha 75 has been treated since 1999. Be very aware to NOT overtighten and all will be well.