|
|
Ok, this was originally an
attempt to make a RAM induction system for the 250 however I ran into
design flaws that has set back the RAM a while but gave me a very
effective and workable Cold Air Intake system.
The standard intake method of the CBR leaves a
lot to be desired. First of all, The "Direct Air Intake" that comes on
the bike is a complete farce. Those ducts on either side of the bike do
no more than guide air to the sides of Carb #1 and #4 and the ducted
air has nowhere to so but down and away from the airbox. The
airbox is situated under the tank and has a little pig snout attached
to it that forces the carburetors to draw air that sits stagnantly
above the hot engine. The hotter the air, the less you can fit into the
combustion chamber because it's expanded. The colder it is the more you
can fit in there, because cold air is dense. Therefore, if you can
direct cold air towards the carburetors, the better the combustion
cycle
will be.
My prototype consists of the following.
Polyurethane air-filter
2 lengths of 50cm x 4.5cm corrugated hose
2 x small plastic bottles
Usually, the best place to have your intake is at the furthermost
forward point
of your vehicle, in this instance the two air vents either side of the
top fairing are the best options. First I removed all the air guides as
they are useless as tits on a bull in my opinion. Next, I cut the two
small plastic bottles to fit wide end first into the air vents. Bottles
with a tapered top work best. One thing to make sure of is that your
hose will fit onto the top of the bottle also. Now comes the hard part,
this may discourage some people. You need to cut a slot into your
airbox upper. All I did was cut the snout off, widen the hole and run
the hoses under the tank. Having the hoses running here meant I
had to raise the tank and perform some minor panel beating of the tank.
I connected the hoses to the top fairing and that completed the Intake.
As for the air-filter, there is
no need to shell out $50 to $100 for
a K&N or Unifilter "race" filter as you can make one out of your
old [and
probably very overdue for replacement] genuine filter. The genuine
filter is a crappy cardboard airfilter and would be an ideal filter for
a vehicle traveling along dusty roads, however as I rarely take the
2-fiddy cross country I went to a rubber outlet [Clarke Rubber, etc...]
and asked for some "Automotive Polyurethane" as that is what most race
filters are made from. I removed the cardboard fins from the filter
then cut some foam to fit. This material does need to be oiled though.
2-stroke oil is what they use to oil them, don't go buy "air-filter
oil" as it's just over priced 2-stroke oil. Make sure you remove any
excess oil. I cannot stress this enough. I did some research on the
correct oiling techniques from K&N and they said "Saturate the
filter but don't wring it out. Dab the excess away with a rag."
DO NOT FOLLOW THAT
ADVICE IF MAKING YOUR OWN FILTER!!!
Use some sort of container that you can put some 2-stroke oil in so you
can soak the filter. I found that cutting the bottom off an oil
container and using that works fine. Once the filter is clearly soaked
and fully saturated, you need to make sure that you get most of the oil
out. The best and easiest way is to fold the filter in half then
squeeze the foam so oil comes out and drips down. If you do it
correctly the oil will drip down to a lower section of filter and then
you can squeeze it lower and lower till you get the filter not dry but
only slightly tacky with oil. If you do not get most of the oil out,
the suction of the motor WILL and it will draw oil into the carbie air
circuits. This will cause the bike to seem like it is running rich as
hell all the way through RPM range and sound like a lawn mower. Plus
you will blow mass smoke. Not cool and can be easily avoided by making
sure the filter is not over oiled. Just
remember to oil it
regularly. |
|
|
