RPM drop

Nasser

Newbie
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Apr 14, 2013
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Hello folks
My Mto Sport 912 is due for annual during ground run we noticed RPM drop for a while when exceeding 4500 RPM then returns back to normal !
Any owner has same issue , looking for solution please .
 

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Abid

AR-1 gyro manufacturer
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Oct 31, 2011
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Tampa, FL
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AR-1
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Nasser
You likely should check fuel filter (clean or change it) and also take the carb bowls off and empty them and put them back (align the sealing gasket into the groove carefully). If it still persists, you have to take out the carb jets and clean them because they probably have a particle lodged into them. If you have a Rotax mechanic or an old motorcycle mechanic who knows carbs in general that would be helpful. You should download the IPS for Rotax 912ULS that shows exploded view diagram of Bing 64 carb for the mechanic to look at

If all that is good, then other internal issues could be the cause
 

schmoe90

Magni M-16 Sport Pilot
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Feb 8, 2018
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184
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Roseville, CA
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Magni M-16
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>1000
Somebody at our airport recently had an RPM drop that was the same as the drop when preflight testing the ignition - we've suggested he start looking at plugs, leads etc, but it could get expensive. No idea what's going on with it now.
 

Abid

AR-1 gyro manufacturer
Joined
Oct 31, 2011
Messages
4,962
Location
Tampa, FL
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AR-1
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4000+ 560 gyroplanes. Sport CFI Gyro and Trikes. Pilot Airplane
Thanks any other suggestions please
You may want to join and post this on rotax-owner.com since it is an engine related issue. Might get more responses there
 

loftus

Super Member
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Mar 17, 2013
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1,193
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Ponce Inlet, Florida
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Aircam; Previously owned Autogyro MTO
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I had a sticking needle valve 2 weeks after a 200 hour carb service at Lockwood. Never even gave me a free t-shirt or apology.
 

AgentCheese

Member
Joined
Jul 9, 2020
Messages
59
Location
De Soto, Missouri
Aircraft
Magni M16 914
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500+ in Gyros
I'm with Abid - Small leak in carb or bowl gasket allowing air leakage is only evident at higher RPM's. Friend had the same issue and took him forever to troubleshoot - had a small warp in one of the carb bowls that only was evident at ~4000 RPM. He replaced the entire carb to verify and fixed the issue instantly.
 

Tyger

Super Member
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Nov 25, 2017
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Clermont, NY
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Was that warped bowl on a 914? I know they had some issues with attachment screws being overtightened, especially after using replacement gaskets.
 
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