tachometer question.

L

lostintexas

Cadet
Joined
Nov 6, 2004
Messages
25
i am going to try clams's thread on how to time an 82~ish mercury 80 horse motor on my boat. the boat its self does not have a tachometer but i have an automotive timine light that has a tach function built into it. <br /><br />the problem being is that the timing light was designed for a 4 cycle engine and i am going to be useing it on a two cycle engine. do i just devide the tachs reading by two?<br /><br />light is a innova 3568+ model.
 
L

Laddies

Banned
Joined
Sep 10, 2004
Messages
12,218
Re: tachometer question.

A 4 stroke fires ever other stroke and a 2 cycle ever stroke, so if it's a induction tach I think you have to multiply :confused:
 
L

lostintexas

Cadet
Joined
Nov 6, 2004
Messages
25
Re: tachometer question.

a four stroke fires every other time the piston is at the top of the cycle? a 2-stroke fires every time it is at the top of the cycle?<br /><br />a 4 stoke going at 1000 rpm, the light would only blink 500 times where as with a two stoke, the light would blink 1000 times?<br /><br /><br />this is the reason i am asking. do i just devide by two?
 
L

lostintexas

Cadet
Joined
Nov 6, 2004
Messages
25
Re: tachometer question.

it is an induction tachometer/timing light.<br /><br />if a 4 stroke motor with said tach (going by the spark of the induction probe) is going 2000 rpm, then a 2 cyle motor would only be doing 1000 rpms as the motor fires at the top of every stroke right(for a two cycle)?<br /><br />will this timing light work as a tach as well?
 
Silvertip

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,762
Re: tachometer question.

At any given RPM a two stroke will be firing twice as fast as a four stroke. Divide by two for two stroke RPM.
 
You must log in or register to reply here.
Top