Answers in Red:
What do you mean by "should be able to read the serial number at idle and f
uzzy up to 4000. After 4000 the uncowled engine is hard to read."
See 4 below.
1.- I have zero insulation inside. No carpet, nothing on the firewall, noti
ng on the sides. Airplane not painted but quite slippery based on high crui
se speeds (130-140 knts). Airplane is indeed noisy at my high cruise speeds
.
No interior means no sound deadening. Never just look at speed. Get the p
lane filled and painted. You will notice a difference, even in handling.
2.- I don't have the intake plenum on the engine. Just good old fashion con
e K&N filters. I did that to keep the airplane light on the nose. I was pla
nning to install the plenum after flying the airplane a little but the perf
ormance is so spectacular as it is I decided to leave it alone. I do know t
hat intake noise can be high in the two stroke Rotaxes.
In my opinion you are sucking hot air into the engine and with the XS cowl
there is not as much negative pressure in the cowl. The Bings don=92t do r
am air well but the inlet plenum is necessary for the best MP to run the 91
2S (ULS is the same, it just means it is the uncertified =93Ultralight=94
engine). Cold air plenums work. Spectacular in relation to what is always
subjective. Air speed calibrations bring home the actual performance.
3.- Engine feels silky smooth at the ground when doing runup at 4000 RPM.
That is good. But look on top of the ignition modules. There you will see
the part number. That should be readable with the engine running for a pe
rfect tune. Most folks find even the out of balance Rotax smooth. It shou
ld be like a sewing machine.
4.- Prop not static balanced since the dynamic balance (with spinner) is al
most dead on. Tweaked it to made it better though.
Get the IPS on your balance down to below .07 or less. It makes a differen
ce.
5.- My spinner is off according to what people tell me. Have not fixed that
but it is a light DUC CF one.
Duc spinners I have seen have a weak backplate. The spinner if not true it
will oscillate and fatigue. Never fly with a wobbly spinner. It is alarm
ing when they fail.
6.- Checked blade pitch with a laser tool I made. Will check track though.
OK
7.- I do have a buzzing tach needle and my "used" altimeter wobbles up and
down around 100'.
Wobbles are not uncommon with a static source that has a minor leak. Depen
ding on the brand, look into a rebuild and check your static system.
8.- The muffler used to touch the top of the cooling tunnel but fixed that.
No evidence of interference.
OK
9.- My IAS at low altitude is always at 130-140 knts or so yes that can mak
e it noisy (CAS is a little lower than that)
Have you calibrated your A/S ? Best Cruise for a 912ULS is about 5000 feet
. Runs richer than necessary above 3500 feet or so with the Bing.
My engine: Pulled out of a school CTLS because it reached TBO. Rebuilt (not
overhauled but completely torn apart) by an iRMT Repair Center in Canada.
The owner is an iRMT instructor. Confirmed with Rob Seaton at Rotech that t
he place is legit before buying the engine. No modifications. All stock. Ne
w CKT muffler. I did have a few issues with the engine (needed new ignition
module and had to do some work on the carbs). But it is running good and s
trong.
After a top overhaul (sounds like what they did) compressions should be all
even and above 75 over 80. If the engine is rough, put in new plugs befor
e you do anything. The oil on the cylinders and from the storage oil fowls
them. Run good gas at all times. Coils rarely get replaced on a top over
haul but watch for weak spark. A bad coil iron laminated center will corrod
e over time. The coil ohms out but the spark remains weak. So is one igni
tion is different in its drop on the S model you may need to spend $400 for
a new coil. Check the grounds also on the coil.
That is about all I can suggest for now. My top three would be:
COLD AIR PLENUM
BALANCE THE PROP
GET IT PAINTED. ITS TIME. (Interiors aren=92t cheap I=92m afraid and upho
lsters cringe when they look inside. But the nice interior quiets the plan
e down and does not affect serviceability if done right.)
Best Regards,
Bud Yerly
-----Original Message-----
From: owner-europa-list-server@matronics.com <owner-europa-list-server@matr
onics.com> On Behalf Of n7188u
Sent: Tuesday, November 16, 2021 9:43 AM
Subject: Europa-List: Re: Noisy cockpit
rb@gmail.com>>
Great reply Bud. Very detailed as always.
I will create a checklist and go through the checkpoints you outline. A few
notes based on preliminary reading of your message but first one question:
What do you mean by "should be able to read the serial number at idle and f
uzzy up to 4000. After 4000 the uncowled engine is hard to read."
1.- I have zero insulation inside. No carpet, nothing on the firewall, noti
ng on the sides. Airplane not painted but quite slippery based on high crui
se speeds (130-140 knts). Airplane is indeed noisy at my high cruise speeds
.
2.- I don't have the intake plenum on the engine. Just good old fashion con
e K&N filters. I did that to keep the airplane light on the nose. I was pla
nning to install the plenum after flying the airplane a little but the perf
ormance is so spectacular as it is I decided to leave it alone. I do know t
hat intake noise can be high in the two stroke Rotaxes.
3.- Engine feels silky smooth at the ground when doing runup at 4000 RPM.
4.- Prop not static balanced since the dynamic balance (with spinner) is al
most dead on. Tweaked it to made it better though.
5.- My spinner is off according to what people tell me. Have not fixed that
but it is a light DUC CF one.
6.- Checked blade pitch with a laser tool I made. Will check track though.
7.- I do have a buzzing tach needle and my "used" altimeter wobbles up and
down around 100'.
8.- The muffler used to touch the top of the cooling tunnel but fixed that.
No evidence of interference.
9.- My IAS at low altitude is always at 130-140 knts or so yes that can mak
e it noisy (CAS is a little lower than that)
My engine: Pulled out of a school CTLS because it reached TBO. Rebuilt (not
overhauled but completely torn apart) by an iRMT Repair Center in Canada.
The owner is an iRMT instructor. Confirmed with Rob Seaton at Rotech that t
he place is legit before buying the engine. No modifications. All stock. Ne
w CKT muffler. I did have a few issues with the engine (needed new ignition
module and had to do some work on the carbs). But it is running good and s
trong.
Best Regards,
Chris
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