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Gray Wire
Modification
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The US WR250F comes with the gray wire
from the CDI connected to ground. All the other 250Fs have this wire
disconnected. There are two different maps (spreadsheets) in the WR/YZ
bikes. One is for the YZ and is selected if the gray wire isn't grounded. The
other is for the WR and is selected if the gray wire is grounded. With the gray wire connected an alternate ignition-timing
map is used. The “WRF” map retards the timing at the mid and upper RPM so that the
bike will run with the stock baffle and throttle limiter installed (see link
with actual engine data analysis by TT member
McGrath). If you remove the baffle and alter the throttle stop you should also remove the grey
wire. Most people do not like the alternate mapping and disconnect it, especially after doing the other free mods.
Initially it was advocated to cut the wire, and many riders have. There are
disadvantages to cutting the wire. First if you may initially cut the wrong
wire. Second, if you decide at a later time to return to the original
ignition-timing map it is more difficult. Most now advocate simply
disconnecting the wire from the connector and taping it off with electrical
tape. For more information about this topic see
CDI 101 or the Grey
Wire thread in the ThumperTalk archives. |
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Remove the seat, radiator shrouds, and gas tank.
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Locate the CDI (black box on the right
side of the steering stem) There are several wire looms exiting
the CDI. There are two looms with two wires. One has a black wire and a black
wire with a gray stripe. This is the kill switch. The other two-wire loom,
which usually goes under the frame just in front of the gas tank mounts, has a
black wire and a gray wire. This is the loom you want.
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Unplug the connector. Use a small screwdriver to pull the dust
ring around the gray wire from the back of the connector.
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From the front of the connector use the
small screwdriver to release the tab holding the wire in place and pull the wire
from the back of the connector (Figure 1).
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Plug in the connector
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Tape the removed wire to the outside of
the connector with electrical tape (Figure 2).
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Reinstall the tank, seat, and shrouds.
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Figure 1 |
Figure 2 |
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Click on images to enlarge
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Update for 2003/2004/2005 Model
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The gray wire mod is still applicable to US
WR250Fs in 2003. There is some debate but the gray wire mod may also apply to
non-US models in 2003 as well. There is also some debate on TT as to affect (see
links below). Some indicate there is no real affect, some have reported a bog
developing after disconnection, while others have reported similar performance
improvements as seen on the 2001-2002 models. The wire is located in a different
bundle on the 03+ models. On the 03+ models, the
grey wire is between the red/black and blue/white wires and behind the
black/white wire in the 6 wire harness under the frame (Figures 3-5). Posted by TT member amaxwell:
"do the gray wire mod. I called the local dealer here in Colorado (Vickery).
Nathaniel in service ran me through the dealer setup book that Yamaha gives the
dealers. Step 4 - remove the gray wire, just like the 02. Straight from Japan
that's the setup."
Figure 3 (2003)
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Figure 4 (2005)
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Figure 5 (cut)
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Click on images to enlarge
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(From TT member racinace)
Instead of simply cutting the grey
wire racinace ran it to his unused head light switch (ie, he removed the
lights). When it is really muddy out he leaves the switch in the on position
which gives the stock WRF mapping. When the traction is good or he's riding a
track, he switches the headlight switch to the off position to obtain the YZF
mapping. If you want this mod and still run the lights, any single-pole switch
can be used for this purpose.
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ThumperTalk Archives (updated
12/16/03) |
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Listed hear are what
I consider the most helpful threads. There are more threads on this topic in the
ThumperTalk archives. To find them, search the
YZ250F/WR250F forum. Suggested keywords: gray wire, grey wire, free mods, CDI. |
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