'03 R6 (R6S) high RPM power loss

bmart

Control Rider
Hey all. I'm looking for some good ideas. I've been running thse bikes for years and know about the coil recall and problems. This symptom is similar, but coils have been replaced twice (despite testing showing they're good) and a new coil harnes has been tested and installed also/anyway. Fuel pump went from semi functional to dead while I'm diagnosing the problem, so that is new too. I've pulled the TPS, tested (okay!), cleaned anyway, reinstalled and adjusted. Plugs are newish. I have two of these bikes and spares, so parts swaps are easy at home or at the track. CDI has been swapped to two others with no change in symptom.

Symptom: At high RPM (12k & 14k) there is power loss. Power returns if I back off slightly from full throttle...like a carburetor. This does not happen when the bike is cold, but seems to get worse when it is hot and into the 3rd session of the day. The symptom is not consistent, making it a challenge to diagnose. It can only be replicated in a track environment, furthering my challenge to properly diagnose and repair it.

Open to good ideas from parts swaps to try, to diagnostic help. Bobblehead? Pit Lane Moto? Bueller?

Would really appreciate the assist. Thanks!
 

Chubna

New Member
I'm no expert, but if your looking for ideas I would check fuel pump assy. Might not be heat related, but possibly fuel level (Assuming you don't refuel until after the third session). I've had some issues with fuel pumps reading accurate pressure at idle then at higher RPM dropping off and displaying symptoms of a misfire/power loss. Check pickup and hoses for clogs/cracks as you might be losing fuel pressure. Let us know what you find.
 

bmart

Control Rider
Thank you for the idea. I fill up between sessions and this is the third fuel pump/tank I've tried without affecting the symptom.
 
This sounds similar to a crankshaft position sensor on the way out in a car (called a pickup coil if I'm not mistaken, on the R6). Maybe give that a look.
 

bmart

Control Rider
Thanks. It is worth a look. Plannign to bring a few spares to my next track day to help diagnose. The hardest part is that it only fails at speed (and RPM), so it is one part at a time AT a track event...
 

Ashley Knight

New Member
That model uses a CV style slide in the throttle body (diaphragm type), It sounds like you've got a pin hole or perhaps the rubber dried and got hardened on one or more of these diaphragms preventing the slide to open fully.
 

bmart

Control Rider
Thank you for that. Would it fail so intermittantly with that issue? Twice yesterday it would turn over and but not fire, like it was getting no fuel. Symptoms are the same with the Power Commander connected and disconnected.
 

Ashley Knight

New Member
Not sure about that, but it makes sense that it would run better when cold. If the slides aren't opening all the way, the bike is going to run richer. Cold engines like that. Hot engines...not so much. I would take advantage of the no start situation and use that as an opportunity to determine if the issue is fuel system or ignition related.
 
Top