RPM drop with a 914 above 100%
in 912 / 914 Technical Questions
13 years ago
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Re: RPM drop with a 914 above 100%
by Roger Lee » 12 years ago
Sounds like you may still have a fuel delivery issue.
Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell
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Re: RPM drop with a 914 above 100%
by Rob Seaton » 12 years ago
May be the float bowls gasket is allowing boost pressure to escape? Even if you have no fuel stains around the bowl it can happen. Make sure the bowl is not distorted by over-torquing the bolt and the sealing surface is true. Pre-soaking the gasket helps (thanks to Lockwood for that tip)
Thank you said by: Carlos Chazarra
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Re: RPM drop with a 914 above 100%
by Carlos Chazarra » 12 years ago
Karl, fuelflow is checked as you say, and it is ok. Thanks for the tip.
Rob,....., I saw right crab tray with some kind of leak of fuel, seen some small drop of fuel coming out from the gasket..... And couple of flights ago, some brown colour ( As from fuel) in the other side of that carb, facing to crankshaft.
Check that and replaced for new, and say to you.!
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Re: RPM drop with a 914 above 100%
by Carlos Chazarra » 12 years ago
Today I carried out, again, full power tests, once I have checked and cleaned all fuel pipes, distributor, pipes to carbs, carb bowls, floats, jets, pins, and ....still exactly same problem: no more than 4500 rpm and drop to 4000.
I have checked, one more time, in that position, the level of fuel inside bowls, more precisely, and the difference between left and right is surprising: 40 cc left, 19 cc right.
I observe as well a slight leak of fuel from rear part of the right carb, probably coming from the gasket, not much, but is dry in the other carb.
It, then, seems to be fuel delivery issue, as Roger says, in the right carb, with possibly a lost of boost or fuel in it, (as Rob tells).
Is possible that, if this is the matter, it causes so much drop in t he powerful of a Rotax 914 from 5.500 to 4000 rpm.??
Anybody have seen a case like this?
I will have the carbs overhauled, I think.
Thanks
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Re: RPM drop with a 914 above 100%
by Roger Lee » 12 years ago
Hi Carlos,
A good carb cleaning and rebuild may be a good idea. I sure hope we aren't missing something simple.
Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell
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