Mariner 2.5hp 2 stroke

[ContessaBob]

Need to change the spark plug on a Mariner 2.5 2 stroke outboard. To reach plug, a plastic panel has to be removed on the underside of engine body. Does this just snap open for access? I'm reluctant to force this too much! The only screws visiable seem to hold a flexable part that looks like it acts like a hinge. Can anyone help? Thanks.

 

[Lakesailor]

It has two flexible plastic pins attached to the flap. Just pull down at the front of the flap and it will come off. (famous last words)
See Here Scroll down to page 9, Spark plug
Tohatsu, same motor

 

[ContessaBob]

Thanks Lakesailor.

 

[electrosys]

On the 2B, the plate you're referring to has a kind of hook at the other end from the hinge. Item no. 14 in the attachment.
I assume it's the same cowling arrangement on the 2.5
So - you need to push in a little, then pull down.

 

[electrosys]

Bit of thread drift - the Tohatsu manual gives the spark plug gap as 40 thou (1 mm), whereas the Mariner manual spec is 21 thou (0.55 mm) - that's a huge difference. Anyone throw light on this ?

 

[ContessaBob]

I'm just happy to get to the plug!

 

[electrosys]

I'm just happy to get to the plug!

LOL ...

It's just that I happened to notice the difference. I think the Mariner manual I was looking at (1984) is just plain wrong - even the plug itself is a different number. I'm sticking with 40 thou - the little beastie has been working ok at that.

 

[Fire99]

LOL ...

It's just that I happened to notice the difference. I think the Mariner manual I was looking at (1984) is just plain wrong - even the plug itself is a different number. I'm sticking with 40 thou - the little beastie has been working ok at that.

If the plug is the right colour and the motor is running right, I wouldn't change the gap either.

 

[VicS]

Given the serial number it should be possible to determine for sure the correct spark plug and gap.

At a first guess I'd say NGK BP6HS, or the suppressed version BPR6HS gapped at 0.040" ( 1.0mm)
or one of the pre-gapped ones BP6HS-10 BPR6HS-10. (-10 indicates that it is supplied gapped to 1.0mm)

Alternatively Champion L87YC or RL87YC