Question about 03-05 ignition mapping

I have an 03 YZ450 that I am trying to improve as a woods bike. I have added a DRD 8oz flywheel and GYTR Ti muffler & lowered the gearing, but It still has too hard a hit for my taste. In searching past threads it seems the 03has the hardest hit of the 1st gen motors, so I'm looking for other areas to broaden the powerband. The cams use the same part numbers for 03-05 which leads me to believe the difference is ignition mapping. My question is do the CDI boxes interchange and if so, which one would offer the broadest power for the woods?

Also I'm considering swapping cams and if I understand correctly going to a WR exhaust cam will broaden the powerband at the expense of a few overall ponies? Thanks guys.

It really depends on how much you want to take away from it. If they do interchange, then the '05 CDI will definitely put an end to the fierce hit. Most people thought the '05 was sluggish, and one even said his 250F felt snappier.

Likewise, a WR cam will more than likely be a bit too much off the fastball for your tastes, but I don't know you.

If they interchange, and I frankly don't know if they do or not, the way to go would be with an '06 CDI. The '06 was originally thought of as a "soft" engine, but in retrospect, most people regard it as having a good balance of low/mid and top end power without the brutality of the '03.

Then too, you can use a multi-map ignition like the Vortex, and do just about what you want with it.

The Cdi boxes on all the 450's will interchange, when the boxes are run back to back on the dyno there is no real difference but that is wide open for the most part.most of the timing changes seem to be for smoothing out the part throttle areas. I would think the latest model box you could get would have the most refined mapping for the low end.

The big change from 03-04 to 05 was the intake port and squish area in the cylinder head, in 05 they went to a smaller higher veloicity port design that has stayed around through 09, it seems that this along with cam timing changes have made the bikes feel slower but turn faster lap times.

Thanks for the replys. In response to Grays question about my riding style, I used to be a fast "B" enduro & hare scrambles rider. Unfortunately, I quit racing about 20 years ago due to the usual commitments. Now my son is old enough to go trailriding and I bought the 03 last year to start going with him and plan to run a few hare scrambles next year. I like the power, I'd just like to smooth out the hit and get a little more low end. I have ridden an 06 in the woods and thought it had a great powerband for offroad, almost like an electric motor.

Thanks again guys.

playrider have you though about a G2 or motionpro throttle cam system? My buddy has the G2 and loves it on the trails then he switches back to stock for MX.

The throttle system is something I haven't looked into yet. What year bike does your buddy have his mounted on? How does he feel it improves the throttle control?

He has it on an 06. It reduces the rate at which you slide opens on your carb so that "half throttle" isn't quite half throttle. Its hard to explain but it makes things more progressive I guess?? Maybe someone else can chime in with a better explanation.

I don't think the ignition box's interchange between the yz and wr -- I believe the wr is ac and the y is dc -- but I believe a wr with a stator mod/rectifier (baja kit) will interchange with some wiring? -- check out e-bay for a used vortex , one went the other day for $220 used? Did the 03 y450 come with 12:5:1 or 13:5:1 comp. piston? also a 18" rear wheel would help for traction?

I will be going with the Motionpro throttle system to calm my 04 down a little.

It can be quite a hand full once I am tired on the mx track. But I still prefer it over the newer motors.

I guess I volunteered for guinea pig duty. I bought an 06 CDI box on ebay for $40. If it doesn't smooth the motor out with the ignition mapping, it's no big loss. I believe the 03 motor is 12.5-1 compression. I have considered switching to an 18" rear wheel just for tire selection, but I have also heard the 18" tires in the same sizes are a little shorter.

I don't think the ignition box's interchange between the yz and wr --
They won't. Electrically, they are entirely different.

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