912 ULS cut-off on landing roll

I get the Carbmate delivered to day. I really don't think my carbs are out of sync and at least the Carbmate can tell me if so.....

Report: I got the new Carbmate, hooked it up, ran engine at 3500 rpm Carbmate stay in green on all resolution settings. I suspected the carbs was in sync and the Carbmate verified. I will also get basic vacuum gauges for future checks, as Roger says they are much more accurate.

I did do a half a turn on the throttle screw before checking sync.

The problem I think was the throttle friction adjustment. When you back off the friction "loose" and pull the throttle back, the throttle allows you to go much farther back, which allows the rpm to drop to low. NOTE: My RV12 does not have the small brass throttle stops. Do I need them, I don't know.......
If you tighten the friction and pull the throttle all the way back, the throttle stays at 1700 to 1800 rpm.
So that's "weird" - I just need to keep the throttle friction tight and the throttle does fine.

So I went out flying did 5 touch and goes and some formation flying and all went well.

Anyone every seen this problem with the throttle friction adjustment?

Thanks,
Wallace

The problem with no throttle stop either in the cockpit or at the carb is you can pull back too hard at times and bend the throttle stop plate which then allows the rpm to drop so low the engine can quit. Personally I’d put the cable stops on at the carb cable.

"Just a FYI comment: I disagree that a pair of any cheap gauges are good enough................."

Hi James,

Well my gauges (from a motor bike shop) were cheap as chips. 

Before I use them, I check that the dials are reading the same at ambient atmosphere - they can be adjusted if there is any discrepancy.

In use, I often swap vacuum hose from on to the other, so as to check the readings are the same - so far so good.

The small restrictor taps, for tuning out the vacuum/piston pulses, are a bit fiddly, but functional.

I have no idea how accurate they are but its not about accuracy, its about enabling the same manifold vacuum reading at the same rpm - this they do very reliably.

I don't think they would be suitable for use in a high volume Rotax service/repair shop but they are just dandy for the home mechanic.

Roger Lee wrote:

The problem with no throttle stop either in the cockpit or at the carb is you can pull back too hard at times and bend the throttle stop plate which then allows the rpm to drop so low the engine can quit. Personally I’d put the cable stops on at the carb cable.

So Roger, the throttle plate inside the carburetor bends or a plate on the outside?

>You got a source for the throttle stops, "Link"?
>I assume the carbs will need  to be synced again after installing the stops?

Wallace