A year and a half ago I replaced a 1994
K1100RS with an 1999 R1100S. I loved the (much) better handling,
but certainly missed the top end hit I got from the K. I certainly
didn't want to take the engine apart or do anything drastic, so I tried
the normal routes to getting better response: a Staintune exhaust and a
K&N airfilter. These changes certainly improved the boxer's breathing,
both in and out, but still it felt lethargic compared to my friends' ST-4s.
I then noticed a listing in the R1100S Registry
from a fellow in Australia. He had made a LOT of modifications to
his bike, one of which was especially interesting to me. It was called
an "MBL InDuct," and was apparently a carbon fiber intake duct. I
searched the internet for "MBL", etc. but without any success and finally
e-mailed Australia to learn more information.
What I learned was very attractive; the InDuct
was another bolt-on item (I admit it, I LIKE my warranty) and was designed
especially for bikes with a K&N. Apparently the designer (Mark
Lennon) determined that the limiting restriction in the intake system was
not the airbox or the air filter, but the intake duct itself. The
InDuct was designed to permit the K&N to work at optimum efficiency
by removing that restriction.
After corresponding with Lennie, he was kind enough
to send me one. Upon arrival I looked it over carefully. It
is a beautiful piece, solidly built and very nicely finished. It is constructed
at least as well as the stock front fender. And of course it weighs next
to nothing. I was really excited, and brought it to my dealer to
install (I admit this too, I am frankly a dilettante!). They were
as impressed as I was and, 20 minutes later pulled my bike off the stand
for a test ride.
When they returned, they took the old duct and
tossed it into the garbage since they were sure I would not be using it
again. And then I went out for a ride.
Wow. What a screamer. The InDuct plainly cures
the remaining bottleneck in the system. It and the K&N obviously allow
the cylinders to fill much better. The surfaces of the InDuct are simply
smoother than the stock duct, and even better, it has a much bigger cross
section. Accordingly, it is just less restrictive, and flows a lot more
air to the engine. Of course the Staintune also allows everything to scavenge
easier too.
Anyway, riding the bike was literally a revelation.
It now picks up speed easier and quicker and is much more responsive.
The InDuct makes my oilhead boxer now feel pretty much like a four valve
Ducati. I have run no dyno tests, but to me the difference is mainly
in responsiveness; the bike feels exactly like it has a lightened flywheel.
Larry, USA
