how can i find out if a tachometer is reading right. i was using a hangar 9 tach just the other weekend on a saito 120 and at idle (very rich idle, trying to break it in) it read somewhere between 400 and 500. am i supposed to multiply that by 10?? it sure didnt seem as though that engine was going that fast. is there a certain way you have to hold the tach, a certain distance? what am i doing wrong here?

thanks

D

I've only used a tach a couple of times and was never able to get a good stable reading.

But I do remember reading about checking their calibration.

Since the inside lights run off of 60HZ means 60cycles/sec, and you have 60 seconds in a minute.

Just holding the tach indoors without pointing it at any motors, it should read 3600 RPM.

Make sure you take all your readings outdoor.

I'm no expert but I hope the above helps make sure that your tach is All right.

Good luck.

Gryphon,
That is a good suggestion. However, it only works with flourescent lights.
Also, it may read 7200 since there are two peaks per cycle - similar to two blades on the prop.
KW_Counter

thanks for the help, tried it on a fluorescent light and by golly it worked, 360 on 2 blades, i guess i have to multiply it by 10 after all

thanks again

D

I had a similar problem with the Hangar 9 tachometer. Im trying to break in a Saito .91 four stroke for my Hangar 9 Hellcat 60. At full throttle and the engine screaming, the tach only reads about 991. This is my first four stroke, so maybe I'm not used to the lower RPMs verses two stroke. I'll try the lamp trick to see if I can get a better reading.

9900 for a new four stroke is in the ball park...depending on what prop you have on there...

I'm using a 14x6 APC, the tach is reading in three digits (991) I thought it would read in four digits such as (1015)?[sm=71_71.gif]

Ok never mind, I read the above thread, multiply by 10 so it comes out to 9910 RPM duh[sm=idea.gif]