Owners - Got BBR?
Motorsports is synonymous with trick components for
four strokes. They have one of the strongest brand
names is all of aftermarket dirt bike components.
No introduction is necessary. If you have a four stroke
there’s a good chance BBR produces something
you’ll want and it might even be something you
you have a CRF100F, or its predecessor the XR100,
you’ve likely wanted more power...no you need
more power! You’ve probably looked at BBR’s
big bore kits for the fiddy’s and wished they
produced something for the CRF100. The wait is over
with BBR’s 120cc Big Bore kit..
CRF100F has been considered a great transition bike
for those too big for CRF50F but still too small to
handle a CRF150/230F. It’s considered by most
to be a mini, albeit a big mini. In its stock form
it’s not a race machine but rather a capable
trail bike with mild manners.
BBR Motorsports XR/CRF100 120cc Big Bore Kit
Models years 1981-2007
BBR 120CC Big Bore Kit promises to give more punch
to a rather lifeless motor. Our friends at BBR sent
us a kit to install and review. We were stoked to
get started. Our test machine is a bone stock 2001
XR100 with tons of miles on it. We had several test
pilots lined up that ranged in age from 13 to 45.
Our plan was to install just the kit and leave everything
else stock to get a baseline appreciation for what
the kit alone delivered. Then we’d work to open
up the intake and exhaust tracks and rejet the carb.
of the first things you’ll notice upon getting
this kit, it’s typical BBR top quality design,
components, and workmanship. This goes from the packaging
down to the very smallest component. Everything you
need to install this kit is included except for the
know-how and tools.
kit comes with the following:
• Exclusive BBR "big finned" aluminum
• Piston kit
• High performance camshaft
• HD valve springs with aluminum retainers
• Rocker arms with adjusters
• Gasket kit
BBR XR/CRF100 120cc Big Bore Kit
of the things you won’t find in this kit are
instructions. That’s right…no instructions.
At first you might think that’s just wrong.
Actually, in my opinion including instructions would
be wrong. With slight variances from one model year
to another, such as torque specifications or the like
, it’s best to rely on the original source for
instructions on doing a top end rebuild. If you don’t
have a Honda shop manual for your XR100 or CRF100F
get one before you install this kit.
Components and Comparisons
If you’ve never done a top end rebuild on a
four stroke don’t be intimidated. If you have
reasonable mechanical skills and can follow instructions,
the Honda shop manual will walk you through each step.
It can also be a great project for you and your young
rider to do together. They’ll get a great education
on how their bike works and be impressed with your
“mad skills” with a wrench. However, if
this kind of work isn’t for you, your local
shop would be happy to do the work for you.
design, quality, and workmanship typical of
went smoothly and all the parts fit together
perfectly with the only exception the cam
chain tensioner spring
stock power everywhere...down low, mid, and
platform for additional modifications such
as exhaust, intake, and ignition
I won’t be going through a step-by-step install
procedure I do want to provide some useful information.
You’ll need to remove the motor from the frame.
2. You’ll need a clean work surface that has
plenty of space to lay the parts out
A valve compression tool to install the new valve
springs. If you don’t have one and don’t
want to invest in one you can take the head and new
springs to your local shop and they’ll charge
a small fee to install them.
2. Feeler gauge for adjusting the valves after the
3. A quality torque wrench
4. Assembly lube
installation went very smooth with no major problems.
All of the components were a direct fit with only
one exception. The spring for the valve chain tensioner
was not the correct length for our model year XR100.
Fortunately, it was too long and was easily modified
to the correct length.
word of caution on installing the valve springs. You
may be tempted to try an install them without a valve
spring compression tool. DO NOT succumb to this temptation!
All you will do is damage the head and valves and
end up getting the tool or sending it out to be done.
Save yourself the aggravation and your motor the damage
and get the correct tool or have a shop do it for
installing the kit and getting the motor back in the
frame I was anxious to fire it up. For those with
who have direct experience with the XR100 or CRF100F
you know these bikes can be hard to start at times.
I was prepared to kick like a mad mule but was absolutely
shocked when it started on the FIRST kick!
questions I had were immediately answered. For example,
would I need to rejet the carb to get this bike started?
No. Would I need to rejet the carb to have it run
correctly? No. Would it sound different? Not much.
it started I was now like a kid on Christmas morning
with a new toy. I couldn’t wait to take it for
a quick spin and check out the power. All I can say
is wow! What a difference 20cc makes. The old adage
“There’s no replacement for displacement”
was once again proven to be correct. There was more
power everywhere; down low, mid, and up top.
in mind this is still a stock XR100 with the exception
of the BBR 120cc big bore kit. No jetting changes.
No needle changes. No intake or exhaust changes. Just
BBR +20cc kit.
primary test rider was the bike’s owner a 13
year old young woman who has logged tons of miles
on this bike prior to the big bore kit. After her
first ride with the BBR 120cc kit she came back and
all she could say was “Oh my gosh…I love
it!” Her smile was at least 20cc larger if not
the initial install, our test riders have logged dozens
and dozens of hours with the BBR 120cc CRF. First,
the product is rock solid. There has not been a single
problem with the motor. It runs strong and starts
on the first or second kick. Second, it has not burned
or lost any oil during our testing period. Third,
our primary test rider is asked after each ride how
she likes the power. The answer is always the same,
“I love it!”
is just the first installment of this review. From
here we are going to open up the intake track with
a K&N filter, open up the exhaust, install a BBR
rev box, and rejet the carb. We’ll report back
once these additional modifications are complete.
installation which isn't a quick installation.
However, if you have some mechanical ability
and the Honda shop manual you can install
this kit yourself.
chain spring needed to be shortened. This
is likely a variance for this model year.
the owner of the bike: All the adults want
to ride this bike now!
Only Staff Review June 2006
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