Tachometer question

[mondovino]

I bought a new laser tachometer to set the high speed jet on my Stihl 066:greenchainsaw: I tested that it worked by putting the reflective tape on a hand drill and it functions fine. It has a refresh rate of 0.6 seconds and is rated to 99,999 rpm. But when I put the tape on the flywheel between two fins, and then put the starter cover back on. The laser doesn't get a good reading through the square holes on the starter cover.
Any suggestions on how to get a good reading with this type of tach on my Stihl?
Thanks!:help:

 

[heimannm]

Maybe...

That tach system requires the laser (I have an infrared one) bounce a signal off the decal and back, measures how often the reflection comes back.

Sometimes if you hold it at a slight angle you will get a solid reading, but I suspect you can't get the signal bounced back and readable with the decal between the fins.

If you want to use that tach you may have to either find a space where the fins won't mess with the signal reflection that you can read through the cover, or try the decal on the OD of the flywheel and find some way to read it like a drilling a hole in the cover.

Mark