Posted April 24, 2008 - 03:47 PM
I have a quick question that i think you might be able to help me with. When I hold the throttle open at a constent spot my 05 WR450 seems to stutter and jump. Is this a jetting problem or could it be the TPS. Any help would be greatly appreciated.
Posted April 24, 2008 - 04:09 PM
Posted April 25, 2008 - 11:40 AM
How is your carb setup? Do you have a pipe?
Posted April 25, 2008 - 10:41 PM
+2 on the TPS/WR/CDI-itus
The ignition is usually the source of Yamaha WR's stuttering at steady speed and light loads. I see it often on the dyno running at light loads. The ignition spark is monitored by the tach pickup and the air/fuel probe is measuring at the same time. The ignition (engine speed readout) will spike off every few seconds and come back while the wheel speed is steady and air/fuel looks good.
The graphs below are results from multiple runs placed together in each graph. All of these are low-throttle, low power output, just as you find with steady road riding.
The wheel speed is in the 30-45mph range and the throttle range is low throttle with low power output at the same time. The air/fuel mixture is in an acceptable range and isn't causing this type of result.
Many more runs on this graph, using both 4th and 5th gear.
Posted April 26, 2008 - 02:19 AM
Now the next question is, can a CDI from the same year Yamaha YZ resolve the problem (enough to justify the expense) for a WR?
We all pretty much run with the Grey wire disconnected already. Or does a bullet have to be bitten and a Vortex bought?
Posted April 26, 2008 - 05:19 AM
Posted April 26, 2008 - 12:42 PM
Posted April 26, 2008 - 01:00 PM
It 'reads' the throttle position and tells the CDI. To this it adds the engine rpm and determines the amount of spark advance.
Your owners manual has a pretty good section on it.
Posted April 26, 2008 - 01:34 PM
Posted May 27, 2008 - 06:04 PM
Posted May 28, 2008 - 02:23 AM
Posted May 28, 2008 - 03:02 AM
Posted May 28, 2008 - 03:16 PM
Soulds just like mine - low rpm is OK at steady throttle, but higher RPM sputters and misses every couple of seconds. I'm going to give JD jetting a call today to see what he thinks about fixing the problem.
now that mine is jetted(TPS is still connected)... I can say that mines misses too. I only notice it when I'm tring to hold steady throttle. for example trying to do steady 25 mph on a park road with a speed limit. I don't notice it at all on the trail.
I'd like to try a new CDI, but the only one I know of is the Leovince fast box. and I'm not really interested in paying $400+ just to try it out.
Posted June 10, 2008 - 03:17 PM
Its $180 replacement and would like to know if its going to fix the problem before I lay the ca$h out.
If I change the TPS. Are there adjustments to be made once it is on, or is it just plug and play??
Posted June 11, 2008 - 06:12 PM