How to get RPM Reading

[BRJ]

I have a 1981 40hp Merc, pull start with no instumentation, I want to know the RPM it runs at to see if I can change props to get higher speed, How do I measure the RPM. I have a Tac from my racing gokart that attaches to the plug lead but it is setup for a single cilinder engine is there someway I could use it?

BRJ

 

[j_martin]

Re: How to get RPM Reading

I have a 1981 40hp Merc, pull start with no instumentation, I want to know the RPM it runs at to see if I can change props to get higher speed, How do I measure the RPM. I have a Tac from my racing gokart that attaches to the plug lead but it is setup for a single cilinder engine is there someway I could use it?

BRJ

If the go-cart engine is 2 cycle, it should work. If it's 4 cycle, divide the reading by 2.

Any spark plug on a 2 cycle fires once per round.

hope it helps
John