Track RC390 losing power mid corner

[LBRC390]

My track only, 2016 with Chad's map and center back exhaust is completely losing power in corners. Here's more context:
At Streets of Willow last summer the bike exhibited this behavior in turn 2 (3rd gear right). It would be totally normal through the gears on the straight, fine in the fast kink, downshift normally, then as I'm picking the power back up on exit I lose drive, throttle does nothing for a moment, then power comes back on like you're trying to launch in too high of a gear, until eventually it seems normal again. I pulled in to the pits. Nothing obvious. Went out again, same corner, same thing.

I went through the bike over the winter. Checked valves, changed plug, fuel filter, and checked for bad grounds. Didn't find anything. Went to Apex kart track earlier this summer and the bike ran great in sweltering heat.

Yesterday, back at Streets of Willow with Compact Octane (a great small CC track day group btw) my bike exhibited the same behavior again, but this time in turn 10. Turn 10 is a left, but also 3rd gear after a straight. Back to the pits. Nothing obvious. Thinking maybe lean angle sensor. Fix the pendulum so it doesn't swing and test it by laying the bike on it's side and it doesn't die. Back out on track, all good until turn 10 when it does the same thing. WTF?

Thanks for reading, and I'll appreciate any thoughts.

 

[RickCrespo]

Interesting behavior. Any chance you got any video of this happening. I would suggest getting video with full view of front straight, RPM and right hand if at all possible. This way you can hear and see rpm and what your right hand is doing on track.

 

[LBRC390]

I do have a couple of clips from when it happened last year. I wasn't filming this last time.
The first vid is the very first time it happened. I was maybe 5 laps into a session. Up to that point, the bike was running perfectly.

This second video is the the very next time out. I had looked for something obvious in the pit, a loose ground, disconnected lean angle sensor, loose spark plug cap, etc. All seemed fine. I went back out and it immediately happened again.

Thanks for looking and I'm interested to hear your thoughts.

 

[RickCrespo]

Holy Shit!! That is terrible, sorry you are going through this. There are a couple of things I have to ask. Does the bike have any piggy back system in it like Power Commander? If so disconnect it, ride without it and see if it happens, do the same if you have a quick shifter. Second, have you looked at the fuel filter, and lastly have you gotten the fuel injector cleaned? The only thing I would say if none of those things deal with the problem is swap out the ECU. I hope this helps and good luck.

 

[LBRC390]

No piggy back systems and no quick shifter. I changed the fuel filter after the first incident. I haven't changed the injector, so I'll do that. I hope I don't have to change the ECU, but that's definitely a possibility.

 

[Superpacman13]

Typically when I encounter this issues its detonation in the combustion chamber on part throttle and slowly progresses as the session goes on. If you have an exhaust and no tuner this is a highly likely scenario

 

[LBRC390]

I have a stock header, and Arrow exhaust from there. My ECU was flashed by someone Chad Wells referred me to, with what I believe to be "Chad's Map".
Would you recommend a piggyback tuner or a standalone like the ARacer?

 

[1JZSupra]

Typically when I encounter this issues its detonation in the combustion chamber on part throttle and slowly progresses as the session goes on. If you have an exhaust and no tuner this is a highly likely scenario

I agree with this. This sounds like it's a misfire.


You are saying it is a Chad's Map, but the thing is that doesn't always mean it's going to work for your setup. How does your spark plug look? If I was to take a guess I would say you are running lean.

 

[LBRC390]

I spoke with him about my setup, and my intentions for the bike, and he said it was appropriate. However, it has never been on a dyno, so I don't really know if the fueling is as it should be.

 

[yowsaboss]

If I am understanding you correctly, this is a product of lean angle. You can duplicate the gear/ rpm with the bike vertical, and it doesn't happen. So checking the fuel filter was a smart move, I think I'd be inclined to remove the tank and investigate to fuel pickup, there aren't any blockages or obstructions. Why would a bad injector only malfunction when the bike is at lean, unless there's some sort of electrical/ connector issue? A loose connector that's acted upon by gravity, etc. Anyway, rule of thumb is check the simple things first. Although it's a PITA to remove the tank and the fuel pump, it's cost-free. Replacing parts systematically as a way to diagnose is sometimes necessary. but it certainly is not free.