ATV - 1997 Honda TRX 300EX Donor Bike - 1996 Kawasaki KX
250 Total Time to Complete - 10hrs.
There we were, with Mikey's 300EX
and a pooched motor. Bad
piston, con rod, cylinder, cam, follower..... It wasn't good. Looking
at spending the better part of $1000.00 Cdn to rebuild it. Thing is,
that it was already a 383cc kit from 4-stroke Tech, with a modified
black box, a White Bros - E series pipe and a race cam, so there wasn't
a whole lot left to do to it, and I hate putting good money into
something and at the conclusion, only having what you started with.
searched (not too far) and found a mint 96
KX250....(things that make you go hmmmm......) Let the fun begin.
Below is a
series of shots with explanations, that
we took during the conversion process. Let me say that the finished
product is impressive. We drag raced it against two slightly modified
Raptors and the outcome was a draw. The Raptors both have pipes (1
GYTR, 1 White Bros E Series) Both Raptors have jet kits, and modified
air boxes. The KX motor is stock. I'm pretty convinced this bike will
take a stock Raptor - we have one of those too, but the pilot was
unavailable for testing at this time.
At present we have no lighting
coil, but will salvage one off a KDX 250
to retain the EX's factory lighting.
The goal of the project was to
not only install the KX250 motor into
the 300EX frame, but to noy damage the EX in case we ever wanted to go
back (???). With the exception of a cut breather tube and a couple of
brackets welded to the frame for the rads, all EX tabs, mounts and
parts were not harmed during this installation.
The EX is stripped and
Mikey (left) and Baby Man strip
The 250 sitting on blocks inside
the EX frame.
Chain alignment and swingarm
geometry set and checked,
custom engine brackets fabricated.
With just a slight tweak in
the vise on the 1st bend in the pipe, and
with the pipe installed on the opposite side of the machine, it bolts
right on. Note the outlet of the pipe is near verticle (wrong!)
Baby Man cutting a 30 degree
angle about 4 inches in from the outlet of
the pipe. Rotating the cut piece 180 degrees allows for the proper
transition to the silencer. This also enables the volume of the
expansion chamber to remain constant. The angle was cut so that the
pipe hugged the frame member and therefore would minimize impact to the
Approximately 4" of similar
diameter pipe was used to place the
silencer in the desired position. The stock 300EX battery holder was
moved to the other side. The solenoid was discarded. Note that one of
the original battery mount captive bolts os used to mount the silencer.
The semi finished product.
Routing the pipe this way allows the stock
plastic to stay on the machine. Note the stock breather cone comming
out of the air box. It was cut just before the first rib to facilitate
a flexible pipe connecting the KX carb to the 300EX air box. The air
box cover was removed to allow for sufficiant air flow.
(From left - The Panz, Mikey,
Young Jeff and Baby Man) The radiators from the KX were
mounted on the front frame member - just
behind the front bumper mounts/ The hoses were run along the horizontal
Baby Man mounting the other
rad and checking the fit of the stock rear
plastic against the pipe. The front fender supports were left in
tact on the right side but needed to be modified on the pipe side.
The Panz securing the last of the
The rad hoses are run in front of
the shocks and along the frame.
The stock KX kicker is too
long. It was cut and aluminum welded and a
larger contact plate attached to it.
The front plastic fit well,
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