Martin,
I know the XS uses a Rotax ring mount and changing engines from the UL to t
he ULS or 914 basically fits on any XS existing Fire Wall Forward (FWF), bu
t the exhaust bends may be close to the cowl front and the ULS new fuel pum
p gets pretty close to the cowl also. So some fiddling required.
The Classic is somewhat different because of the shorter nose and exhaust s
ystems changed slightly between the UL and ULS. The 914 on the Classic dur
ing an engine upgrade was a pain. Frankly, I just installed a whole new XS
FWF on my Classic and it was worth every penny. The high torque starter R
otax provides is a bit long for the Classic. Consider the aftermarket Sky-
Tec starter as it appears to fit and is roughly half the cost and the same
size as the original Rotax low torque starter.
I didn=92t recommend any 912ULS at Custom Flight until after 2006. Hard st
arting, poor starters needing 12.5 volts to start, kick back on start, spra
g clutch issues, case cracking, horrible shutdown and start up shaking, etc
. just sowered me to recommending the engine. After 2006, Rotax finally ma
de adjustments that addressed these issues. Although they never admitted t
o what they had to do it was obvious when the new engines came out. Field
reports indicate the 912ULS (post 2006) are as reliable as the 80HP UL.
The 912ULS new case is stronger, the ignition timing and boxes are optimize
d for smooth starts and running, it is equipped with a high torque starter
standard, and many other little touches that have completely changed my out
look on the 912ULS. The purchase price is very near that of a rebuild 912U
L that is 1000 plus hours old. I can do carbs, so the 912ULS is actually m
ore appealing to me than a 912iS fuel injected engine as its fuel economy d
oes not completely trump the maintenance complexity and cost over the short
term.
Don=92t get me wrong. The iS engine starts and runs smooth, is very econom
ical, and very complex. Your ability to maintain the fuel/electronics has
been removed from the average owner/operator. Problems currently are with
the automatic electronic fuse box switching controls failing, overheating o
n the ground due to its running in lean at all times, a much larger, or fan
augmented, radiator is a must for summer time operations, a larger or mult
iple oil coolers are needed to keep the oil in limits, troubleshooting guid
es are still in flux so give your dealer a break if he can=92t give you a q
uick turn around. I have worked with a number of Pipistrel owners with the
iS and Lockwood and Pipistrel have taken ownership of fixing the issues un
der warranty, but slowly and in my opinion, incompletely. Pipistrel has ha
d to add fans to the radiator (as has Lockwood on the AirCam), larger oil c
oolers, and Pipistrel had to make cowl modifications which were better, but
not enough.
Although the 912ULS burns more gas, it doesn=92t overheat on the ground, is
easier to troubleshoot, annual maintenance doesn=92t require a trip to the
Rotax dealer, and is quite a bit cheaper to buy. One can install a carb l
eaning work around (HACman) if high altitude fuel economy is needed. The H
ACman works by lowering the float bowl pressure via a needle valve controll
ing vacuum from the intake manifold to the float bowl tube. The lower pres
sure in the float bowl reduces the flow slightly through the main jet. (A b
it Rube Goldberg, but it is effective if you fly above 3500 MSL. It takes s
ome fiddling with part throttle setting and even finely adjusted needle set
tings to fine tune your mixture to get the EGT in the proper range. WOT mak
es it less effective as the manifold and carb throat pressure are nearly eq
ual.)
Do not be sucked in to the =93big bore, higher power or other aftermarket c
ylinder and cam mods=94 as the mean time between failure is just not docume
nted. Keep the engine reasonably stock. One exception is what I call the
=93Columbian Turbo mod for the 912UL. This is a reasonable turbo normalizi
ng of a stock UL 80 HP to about a 95 HP engine. This mod is now made by an
Italian company as well. Basically a small auto turbo with dash pot, usin
g Rotax type plumbing, a different exhaust geometry and the stock carbs. T
he key is it is a low boost pressure giving more sea level performance at h
igher cruising altitudes. Pricey, but well within the capabilities of the
912 as a 914 is just a 912 with a different set of carbs and turbo manageme
nt system. Other companies have what they call =93Bad Ass=94 and higher ou
tput mods increasing output beyond the prop capabilities. Quite pricey, an
d as I found on the Jason Parker fuel injected turbo conversion, prone to o
wner/operator tweaking which over boosted the engines making reliability a
problem. Props are made in certain power ranges: 80-120, 125-140, 150-180
, 250-300. Check your prop capability before upgrading your engine or you
may have not just engine costly problems.
Just my two cents.
Bud Yerly
Custom Flight Creations, Inc.
Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Window
s 10
________________________________
From: owner-europa-list-server@matronics.com <owner-europa-list-server@matr
onics.com> on behalf of Martin Tuck <MJKTuck@cs.com>
Sent: Saturday, July 13, 2019 10:13:51 PM
Subject: Europa-List: Rotax 912ULS
I think I may have traced my intermittent starting problem of my old
912UL to the ignition boxes, so I'm weighing up my options.
Two new ignition boxes are around $1,000 each (!) so I'm not sure I want
to sink that kind of money into a 20 year old engine even though it only
has 300 hours on it.
I like the look of the 912ULS, it has a bit more power, a heavy duty
starter and a slow start module that seems to have resolved the ragged
starting issues of the early engines.
If you have a 912ULS I'd be interested to hear what you think of the
engine and how long you have had it. Also, will it fit in the same
engine ring mount as the 912UL - I'm thinking particularly of the size
of the starter.
Many thanks,
Martin Tuck
N152MT
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