Dyno Graphs showing Yamaha TPS Problem

4 replies to this topic
  • Yamahafan

Posted June 12, 2008 - 05:54 AM


See James Dean's post #7 on the following WR450F thread for excellent dyno graphs illustrating the Yamaha TPS sputter problem.


  • grayracer513

Posted June 12, 2008 - 10:04 AM


This dyno chart is for a WR450F, not a YZ450. That bike has a different ignition map, and a completely different CDI unit. I fail to see how this applies in this forum.

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  • Yamahafan

Posted June 13, 2008 - 05:05 AM


Gray -

Are you saying that YZ450Fs don't have a similar TPS sputter problem?

My 2006 YZ450F does. I have seen many people post that you can remove the sputter by properly jetting the bike. This graph would prove that jetting can not completely fix the problem, unless you are saying that the WR CDI is so completely different than the YZ CDI that there is no problem with the YZ CDI. In that case, the WR riders would be buying used YZ CDIs to fix their TPS problem. From the aforementioned thread, they are not buying YZ CDIs, but are instead buying aftermarket race CDIs.

  • grayracer513

Posted June 13, 2008 - 06:01 AM


Yes, at this point, absent any other evidence to the contrary, I am saying that. For one thing, neither of my '06's have the problem, nor do any of my friends who have followed my set up advice. Then again, I don't run the huge pilot jets many people do, I don't obsess over eliminating every little bit of decel backfire, and I have made no attempt to get the bike to be able to put up with instantly opening the throttle all the way from idle, so that may have something to do with it. Both mine run very cleanly throughout the throttle and RPM range.

The electrical system on the WR is different from the stator up, and the YZ CDI is a completely different box than the WR has. They will not interchange. The stator on the WR is not just a bigger version of the YZF, it's wound differently, having one circuit rather than two.

  • mikedabike

Posted June 13, 2008 - 07:21 PM


I have always been able to get rid of the stutter though jetting. On my 04 I spent a lot of time trying to get rid of it including unplugging the tps. Finally fixed it by going to a smaller pilot than everyone was recommending. I ended up with a #42 when everyone was recommending #45's and 48's.

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