Mods - Is order important

4 replies to this topic
  • Old Man Rider

Posted February 04, 2005 - 08:52 PM


I have reviewed all of the mods articles and have a few stupid questions: I believe with my limited mechanical ability I can complete the following by myself: remove exhaust baffle and grey wire. Does it make sense to do these changes without doing the others? Will this increase the performance? What about if I only remove the exhaust baffle? Second question: Are these changes bad for the bike? A friend suggested not to make the changes due to Yamaha designing the bikes components to work together - tampering with them will throw things out of sink. Thanks for your help - I apologize in advance if these questions are covered elsewhere.

  • banffboy

Posted February 04, 2005 - 09:26 PM


If it's new... I would think the throttle stop mod would be your first :cry:

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  • WheelsUp

Posted February 04, 2005 - 09:30 PM


The thing is jetted so poorly that it won't run right from the factory anyways.
Yamaha built it the way they did because California told them to, not because their engineers wanted it that way. To see what the engineers wanted, look at the YZ.

If you can pull the exhaust restrictor and grey wire, you can remove and replace, or remove, cut, and replace the throttle stop screw.

I'd say that the throttle stop screw will have the biggest impact. Stock, you only have 2/3 ro 3/4 throttle.

The grey wire and exhaust restrictor will definitely help. Unfortunately, you can't move the jet needle on the '05 WR... the only option is to rejet. The JD kit isn't cheap, but it gets very good reviews.

  • new04450

Posted February 05, 2005 - 06:20 AM


Since I see the screw issue come up here I will go and ask now do you leave 18mm from the bottom of the head of the screw? :cry: I just got my WR this week, and plan on doing the gray wire and the screw- It looks like both are an easy mod to do. This is my 1st off road machine, so go easy on me.

  • WheelsUp

Posted February 05, 2005 - 09:24 AM


The simplest way is to go to the dealer and buy the YZ screw.
The 450 screw is a couple of MM shorter than the 250 screw, but either will work in either bike (I'm running the 450 screw in my 250)

Overall length, including the bolt head, should be between 22 and 25mm.. IOTW, stand the screw "up" on a table and the tip will be 22 to 25mm above the surface.

If it is too short, the slide will hit the carb cover and eventually crack it. If it's too long, you get less than 100% throttle. The shorter 450 screw does NOT allow my 250 slide to hit.

The hard way is to pull the air filter, look into the carb with a mirror, have a friend pin the throttle, then back out the screw until the slide is exactly 100% open. At that point, measure the length of the exposed threads and cut exactly that much off of the tip.
This is a little more difficult because you're looking into the airbox on the left side and the screw if on the right :cry:


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