It has been well documented the problems with analog tachs and the two-stroke Rotax motors.
Has anyone ever encountered a situation where your analog tach on a 912 has become untrustworthy? I think I may be there... :confused:
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It has been well documented the problems with analog tachs and the two-stroke Rotax motors.
Has anyone ever encountered a situation where your analog tach on a 912 has become untrustworthy? I think I may be there... :confused:
Larry,
You could just use the dynavibe and verify your tach with it. Maybe even balance your prop at the same time. :D
JimS
I have a digital handheld tachometer that seems to be quite reliable. Unfortunately it appears to be unavailable now. I was in a box of stuff that was being discarded so I grabbed it. CERMARK, one touch digital tachometer came from Wag-Aero. If interested I can give more info. The box is marked $54.95. Cermark has a website but does not show this item. Apparently it was not a successful product.
To check your tachometers accuracy, you can use the digital tachs sold at hobby shops and I think I have seen them at Harbor Freight. $15 or 20, very accurate and you can switch from 2, 3 or 4 blade readings. You can take readings sitting in the cockpit or standing in front of the plane, with no wires or other connections to the engine. Just aim it at the prop while the engine is running, they really work.
Larry,
The tachs shipped with the early Model IV kits were notoriously inaccurate. I found mine would change readings depending on ambient temperatures. I also bought one of the hobby shop optical tachs and used that to calibrate the panel tach. Eventually I made a permanent knob that was mounted on the back of the tach and I would regularly check the revs with the optical tach and could then reach under the panel and adjust the knob.
I have the Rotax analog tach and was able to check it a few days ago when I had my engine/prop dynamically balanced. It was right on.
Yeah, I had a problem with the 912uls tach. When putting the ring mount to the engine I took the tach pickups off and neglected to put one of the shims back. Tack showed good to 2000 rpm, then became very erratic when throttle was added. Putting the shim back resolved the issue. But this was human error...