Install of RPM Gauge?

[Doug G.]

 

EDIT: Disregard, having a brief "stupid" moment. All plugs fire on every stroke in rotax 912/914 carb series, there is no distributor and they don't make an effort to simulate one electronically.

That's something I didn't know. Is this exclusive to Rotax, or common practice?

[Anticept]

That's something I didn't know. Is this exclusive to Rotax, or common practice?

 

It's a rotax thing in the 912 and 914 carbed series. They were designed in the 80's. It's not really a necessity to have a distributor for CDI ignition, that's more of an artifact left over from magnetos, and the plugs are dirt cheap. Still, because of this, plug utilization is doubled, effectively shortening their life.

 

I'm not sure if the injected versions waste sparks since they do tune the spark timing live. Maybe there is a safe mode if the ECUs sense problems.

 

 

Corey,

 

I'd get the 4 stroke unit and then it should read correctly. I'm going to look it up in the ACS catalog.

 

Thanks,

Rich

 

As tom said, since it senses the spark, you need to use the 2 stroke version.

[Tom Baker]

That's something I didn't know. Is this exclusive to Rotax, or common practice?

 

I have a friend with a Thorp T18 that has electronic ignition, and it has a wasted spark too.

[Rich]

On the first link that Burger listed, find "Tiny Tach" on the left menu.

Find listed operating instructions and the TT2A  is user adjustable for various spark configurations.

This seems like the way to go for a good and relatively inexpensive back up to the Tru Trak EDM display. I'm going to purchase one on Monday.

 

My Tru Trak EDM needs a filter to correct the erroneous readouts. That will be installed when I get the diagram from the dealer.

 

I also didn't know that the 912 had two sparks per cycle.

Thanks for all the input, time and links.

Good weekend to all.

 

Rich

[Rich]

I installed the Tiny Tach yesterday following the instruction sheet.

The unit is set to 180* for two sparks per cycle. It reads correctly at idle but is nowhere correct at higher RPM's. The most I get is 3700 4100 at WOT and it jumps wildly between the readouts.

 

I've tried 3 wraps, 4 wraps coiled close together and with a gap in between. Nothing works correctly.

 

The instructions say that the wire can be ran together with any other wires and that's how it was run.

 

I've used a TTach on my previous 2 cycle 503 Rotax and it read perfectly. Not sure what the problem is here. Any ideas would be appreciated.