The easiest way to diagnose
leaking intake manifolds is by visual inspection using a
flashlight. However, they may be leaking in the back
or the cracks may be so small that they are not visible.
Method 1: Start the bike, let it
idle and spray some starter fluid around the intake
manifolds. If the RPMs increase then it is obvious
there are leaks.
Method 2: Start the bike, let it
idle and spray some water mist around the intake manifolds.
If the RPMs decrease then it is obvious there are leaks.
(I've only used Method 1 but I've
read of others using Method 2.)
If you have a leaking intake
manifold or several then it makes sense to replace all of
them with new ones. Also, if you've decided to renew
an old bike that's got high miles then you might want to
consider doing this as preventative maintenance.
to jump to replacement instructions for a K100RS4V, K1 or
K75 or K100:
Intake manifold (1) -
Though it may or may not be
necessary, you may want to also consider replacing the boots
above the throttle bodies (4) as well - part 11611460755.
From the factory these are attached with one-use 48.5 mm
(lower) and 50 mm (upper) Oetiker clamps. I usually replace
these with 5/16" stainless steel hose clamps to simplify
future maintenance and eliminate the need for an Oetiker
Disconnect the front fuel line
from the fuel tank and both fuel lines from the fuel rail.
Loosen the large hose clamp at the back (right front on the
bike) of the air box above the throttle bodies. (a.k.a.
Remove the lower Oetiker clamps. (I cut them off with
a Dremel cutting wheel.)
Disconnect the crank case breather hose at the rear of the
Pull the plenum towards you to remove it.
Pick the wire clip off of the throttle position sensor
connector and disconnect it. (Light blue circle
above.) Put the wire clip back on the connector so it
doesn't get lost. When you reinstall this you don't need to
take the wire clip off as it will slip over the tangs on the
sides of the TPS's connector to lock the connector in place.
Disconnect choke cable.
First undo its locknut and then unscrew it all of the way in
order to move it to the side to get enough slack in it to disconnect it.
1990 and earlier: follow the wires for the choke switch to
its connector and disconnect it.
Remove the screw type hose clamps the hold the throttle
bodies in the intake manifolds. Note their positions as
you'll want to reinstall them in roughly the same place in
order to keep them from interfering with throttle movement.
Remove the throttle body assembly.
Each intake manifold is held on by two machine screws.
Remove those and then remove the intake manifolds.
Clean their mounting surfaces and install the new intake
manifolds. (9 Nm - 80 in-lbs)
Installation of the remaining parts is the reverse of
Synch the throttle bodies -
for a one page printable copy of these instructions.
K100RS4V, K1 or K1100:
Intake manifold (1) -
O-ring (3) - part
Manifold to TB boots (5)
- part 11611461739
You should also replace the boots
that go in between the intake manifolds and the throttle
bodies too. From the factory these are attached to the
bottoms of the throttle bodies with one-use 48.5 mm Oetiker
clamps. I usually replace these with 5/16" stainless steel
hose clamps to simplify future maintenance and eliminate the
need for an Oetiker clamping tool.
Remove the two lines from
the fuel rail.
2) Remove the two bolts holding
the fuel rail to the cylinder head and pull the fuel rail
and fuel injectors out of the intake manifolds.
3) Lift up the throttle bodies
and remove the Oetiker clamps that hold them to the bottoms
of the throttle bodies (I use a Dremel cutting wheel for
this) and remove the boots.
4) Undo the two machine screws on
each of the intake manifolds.
5) Clean the mounting surface for
each intake manifold and install the new intake manifolds
and O-rings. (9 Nm - 80 in-lbs)
6) Install the new boots to the
bottoms of the throttle bodies. If
using 5/16" hose camps instead of Oetiker clamps then be
sure they are rotated so as not to interfere with throttle
7) Install the throttle bodies on
the intake manifolds.
8) Put a light coating of engine
oil on the O-rings near the tips of the fuel injectors.
Reinstall the fuel rail and fuel injectors into the intake
9) Re-attach the fuel rail to the
cylinder head. (7 Nm - 62 in-lbs)
10) Re-attach the fuel lines.
11) Synch the throttle bodies -
© 2013 Drake Smith - Please do
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