2008 won’t idle, tried a bunch, weird issues

What is even more surprising than getting this bike for $3k, is having spent almost that much on the project bike, with still no end in sight. At least now, like you say, this can become a long-term project.

johnkol wrote:

What is even more surprising than getting this bike for $3k, is having spent almost that much on the project bike, with still no end in sight. At least now, like you say, this can become a long-term project.

Don’t even get me started! But yeah, I sourced a used top end, complete with jug and piston for 550.00, including a brand new gasket set. We’ll see where this all ends up. I’ll keep this thread updated for sure.

Good call on getting a complete top end, I think you're going to need it.

Let us know what you find as you replace components.

johnkol wrote:

Good call on getting a complete top end, I think you're going to need it.

Let us know what you find as you replace components.

It’s ironic that I kind of hated the idea of a WR at all while dealing with the bad one. So I kind of questioned my judgement when I saw this one pop up. But man, what a difference it makes when something is clean and well loved.

I'm surprised you still have the resolve to pursue the restoration, a lot of people (me included) would have given up at this point. Commendable mental strength!

Alright new jug and piston on. Timing chain came off bottom sprocket, been at it an hour and cannot get it on to save my life. I don’t have a flywheel pulled but I’m sure that’s the easy and next step. I was really hoping I could guide it back on from the top. Any ideas?

Do you have the cylinder head installed or not? There needs to be some tension on the chain, and then if you rotate the crank the chain should align itself with the sprocket.

If that doesn't work, then if you remove the cylinder it should be easy to guide the chain onto the sprocket.

johnkol wrote:

Do you have the cylinder head installed or not? There needs to be some tension on the chain, and then if you rotate the crank the chain should align itself with the sprocket.

If that doesn't work, then if you remove the cylinder it should be easy to guide the chain onto the sprocket.

OK figured that one out, not fun. Major updates for you, I think we are close, truly.

New head is on. Timing good, valve clearances good. Fresh gaskets and oil. Also new throttle body is on sir a known good TPS.

Bike starts, smoked like crazy, probably from fresh build. Smokes clears up but now it’s “smoking” from what I believe is an extremely rich condition. Absolutely reeks of fuel. Messed with CO settings with no real change.

I want to note that the TPS is back to reading wonky. It was at around 55 during all this, at idle.

My theory is the TPS being off is commanding a richer mixture than there needs to be, screwing everything up. RPMs are still reading wrong as well.

With that being said, I do believe we are down to an electrical issue but I don’t know where to start or what to check. I’ve checked the ECU, battery connections are tight, and it’s a new battery. Ground to frame looks fine. The only thing I haven’t deep dived is the main fat bundle of wire from ECU to all those various connections.

Another update! Someone gave me the genius idea to wiggle the wires while TPS screen is up. Sure enough I honed in where it’s going nuts. It’s the intersection where a bunch of wires meet near the ECU… might be on to something!

Update to the update … OK so I wiggled and wiggled and tried to isolate it. Finally I narrowed it down to a wire or two. I would wiggle it and the TPS would go nuts from 19-110 and everywhere in between.


I believe this is where some grounds terminate for the sensors? I’m having a hard time following the wiring diagram though. I took it apart and gently cleaned with WD40. TPS reading is now rock solid.

Bike fired right up and died, OK so I forgot the angle sensor was taken off… it works!

Fired up again and high idled then died… gas is low.


Fired up after adding gas and idles great. I can rev it up and she comes right back down. RPMS are still wrong, my guess is the bundle of grounds next to this one may have corrosion which is linked to CPS so I’ll check that next.

Good job in isolating the problem.

The angle sensor doesn't make much sense: if it's tripped, the ECU won't even allow you to start the bike, so not really sure what went on there.

What you're holding in your hand looks like a relay, but can't determine where this is or what wires are going to it. Is this where you sprayed WD40? It would have been better if you had used Contact Cleaner, or just isopropyl alcohol, but it's OK for the time being.

Did you get a chance to check engine compression?

johnkol wrote:

Good job in isolating the problem.

The angle sensor doesn't make much sense: if it's tripped, the ECU won't even allow you to start the bike, so not really sure what went on there.

What you're holding in your hand looks like a relay, but can't determine where this is or what wires are going to it. Is this where you sprayed WD40? It would have been better if you had used Contact Cleaner, or just isopropyl alcohol, but it's OK for the time being.

Did you get a chance to check engine compression?

I did not check compression.  

I believe this is grounding points to these sensors, see where the 4 blue/black are in line? All I know is wiggling one wire caused the TPS to go nuts.

I think you’re correct on the lean sensor, I meant it worked as in it threw the proper code and wouldn’t allow to start.  I think I confused myself with sensor stuff when gas got so low today.  

I also had this thing unplugged and dangling, I have zero idea what it is, any idea?

I further cleaned up the other boxes of wires but my incorrect RPM persist.  Kind of want to let it go but I know there’s a reason and I’d like to find it.

I will say it still smells rich compared to my “good” WR, I understand these bikes take multiple sensor readings to determine fuel ratio so I’m not sure where to start with that one.

How many wires are going into the connector you're holding? Is it connector 28 in the circuit diagram?

The dangling cable and connector seem to be next to the intake? Could it be part of the AIS that has been removed?

So the engine runs well now, doesn't die, you don't hear a tapping sound, the only problems being that it's running rich and the RPMs are still off?

It is unlikely that the rich condition is due to a sensor; if a sensor is that far off to cause this much trouble, the ECU would have thrown an error code, which raises the question: is the ECU still not throwing any fault codes?

johnkol wrote:

How many wires are going into the connector you're holding? Is it connector 28 in the circuit diagram?

The dangling cable and connector seem to be next to the intake? Could it be part of the AIS that has been removed?

So the engine runs well now, doesn't die, you don't hear a tapping sound, the only problems being that it's running rich and the RPMs are still off?

It is unlikely that the rich condition is due to a sensor; if a sensor is that far off to cause this much trouble, the ECU would have thrown an error code, which raises the question: is the ECU still not throwing any fault codes?

I don’t think it’s labeled as it’s just a grounding point for 6 wires.  That’s my guess at least.


The other sensor im talking about has a cylinder plastic piece on top.  It’s back right if you’re looking from the front of the bike, kind of near back of the seat mount.  

The ECU is throwing codes.  When the TPS was still being wacky and smoking a bunch it threw like 7 codes, some not making sense like the exup servo which was deleted and it has a servo buddy.

i will say this… i was testing diagnostics in the driveway just to see what I could… fuel pump voltage, coolant temp, etc.  when I got to one of them (can’t remember which) the fuel pump clearly primed but didn’t stop priming so I went to next test and it just wouldn’t shut off which I thought was weird. 




Here’s where I’m at now but still confused.  The CPS comes off the stator bundle, and then disappears into the loom eventually making its way back to the ECU.  But where is the actual physical sensor? Is it the rubbery plug kind of hidden by the starter that goes vertical into the crank case? So the stator and the actual plug make the connection? Not sure!

Ok so I see the one I mention above is called the “speed sensor”

For what it’s worth the bike is in much better shape, I would like a way to confirm richness or if I’m just over thinking it. Starts right up like my other WR. Maybe I could start both and just see if I notice a difference in fuel smells.

Not sure about that cylindrical connector (?) because it's not present on my bike; given that all AIS components have been removed from my bike, I'm speculating that this piece is part of that system.

If the fuel pump does not stop priming, this means that the fuel pressure regulator is damaged. You had said that you replaced the fuel pressure regulator, right?

The actual CPS is an induction sensor next to the rotor; the rotor has a small magnet on it, and every time that magnet passes over the CPS, it registers it and transmits it as a crank rotation. There are two wires that come out of it, a red and a white, and they end up in a cylindrical connector behind the front left panel, next to the coolant reservoir.

johnkol wrote:

Not sure about that cylindrical connector (?) because it's not present on my bike; given that all AIS components have been removed from my bike, I'm speculating that this piece is part of that system.

If the fuel pump does not stop priming, this means that the fuel pressure regulator is damaged. You had said that you replaced the fuel pressure regulator, right?

The actual CPS is an induction sensor next to the rotor; the rotor has a small magnet on it, and every time that magnet passes over the CPS, it registers it and transmits it as a crank rotation. There are two wires that come out of it, a red and a white, and they end up in a cylindrical connector behind the front left panel, next to the coolant reservoir.

Ok, tracking on the sensor… makes no sense then since it’s a brand new stator.  I don’t see any damage on those wires either.   Ironically if I wasn’t interested in CO mode I would have never discovered the issue.  So do I just leave it be and assemble the bike?

Looking at the parts diagram, the CPS is part of the stator assembly, so it should have come together with the new stator you installed.

You mentioned that the ECU had thrown multiple fault codes; are all these cleared now? And is the idling screw not having any effect on the idle speed?

At this point I would say assemble it and see how it works, maybe go on a long ride and see what kind of mileage you get.

johnkol wrote:

Looking at the parts diagram, the CPS is part of the stator assembly, so it should have come together with the new stator you installed.

You mentioned that the ECU had thrown multiple fault codes; are all these cleared now? And is the idling screw not having any effect on the idle speed?

At this point I would say assemble it and see how it works, maybe go on a long ride and see what kind of mileage you get.

Yes it did but I saw a similar post where the lean angle sensor threw the same codes for someone.  I took that apart and someone had glued the weight down, something I’ve also seen on another post.

My theory is when the bike was smoking from being so rich, it’s when the TPS was still at 70, so the bike was all out of spec requesting too much fuel.

The idle screw does work! I have the new throttle body on (the other one was honestly fine but you could tell the screw was just about stripped)

Are we absolutely positive the live RPM reading is sourced from the CPS and not the ignition coil?

Ugh…. Buddy came over. Bike fired right up. We are both super impressed with how far it came.

Cleaned up wiring harness and put it all back together for its maiden voyage. Wouldn’t start. NOTHING significant changed from start, assembly, to start.

Good fuel and spark.

Clearly I drained battery down, charged it up a little and got it started, backfired like crazy with throttle and died. His theory is weak battery.

Interesting to note with key on the turn signals are lightly lit at all times. Headlight not working, when we crank it, headlights come on. Maybe symptom of a weak battery?

When the TPS was showing 70 at idle, it made sense that the mixture was too rich, but now that this has been corrected I don't see why the mixture would still be rich, unless the high RPM reading is a clue.

Good news that the idling screw is now working; one more thing to cross off.

Flynavy wrote:

Are we absolutely positive the live RPM reading is sourced from the CPS and not the ignition coil?

The ignition coil timing is sourced from the CPS, so even if the RPM reading is sourced from the ignition coil (highly doubtful since there are no wires coming out of the ignition coil), the root source is still the CPS.

Flynavy wrote:

Interesting to note with key on the turn signals are lightly lit at all times.  Headlight not working, when we crank it, headlights come on.  Maybe symptom of a weak battery?

No, that's how the WRR works: turning the key to the on position the front turn signals (but not the rear) turn on and serve as extra lights; the headlight will not turn on until the engine starts (safety measure to avoid draining the battery).

Flynavy wrote:

Cleaned up wiring harness and put it all back together for its maiden voyage.  Wouldn’t start.  NOTHING significant changed from start, assembly, to start.

I suspect that "cleaning up the wiring harness" is the root of the problem. Maybe there is a frayed wire contacting either the frame or another wire? Or simply an intermittent connection somewhere?