idles but nothing else

[Superboar]

This is a WR450F 2003. One day it ran fine - two days later it ran a while then ran poorly, then would only idle. Now it starts and idles, but any amount of load and it dies. It will rev in neutral sort of..., it idles while in gear with the clutch pulled in, but let the clutch partially out with a tiny amount throttle or a lot of of throttle and it quits.

This is what I have done:

New battery, fully charged

New plug, checked coil resistance with meter

Disassembled carb, blew out jets and passages (some sand in bowl)

Checked float height

removed in-line fuel filter

cleaned petcock and changed gas

checked Throttle Position Sensor (TPS) with ohm meter

What I intend to do next because all this began after trailering the bike through light rain.

Disconnect all the electrical connections, clean them, then add dielectric grease. Most of these connectors are gasketed but the TPS connection to the CDI unit is not gasketed.

What is left to do before the big-bucks guy gets a hold of it?

[William1]

Sounds like a failed crank position sensor. Get the manual and test it. Though even a test may not categorically prove it is bad (sometimes you still get acceptable numbers on a bad unit)

[William1]

Sounds like a failed crank position sensor. Get the manual and test it. Though even a test may not categorically prove it is bad (sometimes you still get acceptable numbers on a bad unit)

[Treebark]

Sounds like a carb problem. Sounds like main and/or pilot jet is plugged again. Pilot (mixture) screw supplies fuel mostly til throttle is cracked, accel pump provides supply til pilot jet takes over up to about 1/4 throttle, after 1/4-1/2 throttle the needle valve (which regulates the supply of fuel flowing threw Main jet), 1/2- wide open the main jet is controling factor. One other thing to mention is that the mixture screw pulls fuel from pilot jet, but once the throttle opens the fuel is also pulled through another port in body along with the mixture screw. Did you pull each jet out and clear passages?

[FORMA MOTO]

- clogged pilot

- broken clip holding the needle in place

[Superboar]

It wasn't in the carburetor though cleaning it wasn't time wasted because the float bowl did have some sand, nor was cleaning every electrical connection in the harness. It turns out it was in a wiring block where some shop had installed the Baja light kit for a previous owner. The shop modified the block and didn't get one of the contacts seated properly making an intermittent contact. What was happening after it warmed up is that moving the handle bars during the launch would sometimes wiggle the wire just enough...

Oh, and this also solved the intermittent starter problem because this faulty contact was the main connection between the key switch and the rest of the system.