Can Someone Help Explain "Limp Mode"?

[thezidane]

I took my bike onto the track for the first time last weekend. Bike only has 350 miles on it. It ran really well for 2/3 of the track day and then going down the front straight in 6th I noticed the mph just dropping fast and my bike slowing down. I couldn't apply any throttle. I turned the bike off and then back on, no problem starting. As soon as I either went up to a certain MPH or RPM the throttle cut off again. I had to leave my bike at the edge of the track and retrieve it at the end of the day. When I got my bike back it started fine again and didn't seem to have any issues. I didn't really push it to high revs or mph though. I know the bike runs a bit on the hot side so I wasn't sure if I overheated it or if it went into "limp mode" from me over revving it coming out of the corners. My dealer can't get me in to check it for a few weeks and my next track day is in a week. I didn't know if anyone could point me in the right direction in terms of possibilities as to why Limp Mode engages in general, or if anyone knows how to check codes on the bike. Is it like a car where you plug your computer into it? There aren't any codes or lights displayed on the dash. Thanks in advance!

About the bike:
2015 KTM RC390
350 miles before track day, 420 miles after track day
No blinking lights or codes flashing on the electronic dash
No engine mods
No ECU mods/flashes
Stock bike basically.

 

[Ryanthegreat1]

You riding at The Ridge?

Maybe it was starved for fuel like the tank vent was not working creating a vacuum in the tank. Try taking it out for a longer spirited ride and see if it does it again. When it starts acting up pop the fuel tank open and see if that fixes it.

 

[thezidane]

Yea, riding at the Ridge. I never let it get lower than 50% fuel level during the track day. Would you recommend topping it off before each round to make sure the tank is full? Anything I can do to prevent this? Thanks for the reply.

 

[Ryanthegreat1]

Fuel level does not matter so much in this test. Just pressure in the fuel tank. As you draw fuel out air needs to be let in to replace it or you create a vacuum. This stops the fuel pump from drawing more fuel out. Stopping to open the tank would let more air in and allow the bike to run again. Just something to check.

You should check out Motorcycle Track Day Experience - Track Time - Olympia, Wa great group to go ride with. Tiny session sizes. I was out there last Monday and my session had 4 bikes in it. They run a fast, medium, and relaxed group. 20 minute sessions. Ken Hill speaks all day and you can choose to have an instructor for the day.

We have a photographer onsite too.
threesixtyphotography

 

[stevieboy]

If this is the problem there should be an audible sound as the vacuum is broken when the cap is opened. I wonder though as it is a pressurized system with the FI?

 

[simpletty]

LIMP MODE--the slow disappointing walk when this bike breaks and leaves you stranded 50 miles from home. Use it in a sentence pls--My KTM RC 390 stopped running the other day and left me in "limp mode" one hour from my house.

 

[simpletty]

Bluetooth OBD2 Adapter FOR KTM Duke 200 390 RC200 390 | eBay

 

[cjwell]

Don't believe there is a limp mode on these.

 

[KTMGene390]

I took my bike onto the track for the first time last weekend. Bike only has 350 miles on it. It ran really well for 2/3 of the track day and then going down the front straight in 6th I noticed the mph just dropping fast and my bike slowing down. I couldn't apply any throttle. I turned the bike off and then back on, no problem starting. As soon as I either went up to a certain MPH or RPM the throttle cut off again. I had to leave my bike at the edge of the track and retrieve it at the end of the day. When I got my bike back it started fine again and didn't seem to have any issues. I didn't really push it to high revs or mph though. I know the bike runs a bit on the hot side so I wasn't sure if I overheated it or if it went into "limp mode" from me over revving it coming out of the corners. My dealer can't get me in to check it for a few weeks and my next track day is in a week. I didn't know if anyone could point me in the right direction in terms of possibilities as to why Limp Mode engages in general, or if anyone knows how to check codes on the bike. Is it like a car where you plug your computer into it? There aren't any codes or lights displayed on the dash. Thanks in advance!

About the bike:
2015 KTM RC390
350 miles before track day, 420 miles after track day
No blinking lights or codes flashing on the electronic dash
No engine mods
No ECU mods/flashes
Stock bike basically.

Check the spark plug cap under the fuel tank as it's known to come loose on the RC 390 causing the ignition to cut out at random.

 

[thezidane]

Fuel level does not matter so much in this test. Just pressure in the fuel tank. As you draw fuel out air needs to be let in to replace it or you create a vacuum. This stops the fuel pump from drawing more fuel out. Stopping to open the tank would let more air in and allow the bike to run again. Just something to check.

You should check out Motorcycle Track Day Experience - Track Time - Olympia, Wa great group to go ride with. Tiny session sizes. I was out there last Monday and my session had 4 bikes in it. They run a fast, medium, and relaxed group. 20 minute sessions. Ken Hill speaks all day and you can choose to have an instructor for the day.

We have a photographer onsite too.
threesixtyphotography

Thanks Ryan. I'll try to ride it around a bit and see if I can get it to do the same thing. The bike isn't street legal so that should be fun! haha. Track Time sounds great, especially that group size. I had about 20 people in my level 1 riding group and I was stuck behind a guy on Triump Rocket on my first session....he couldn't hardly do any of the turns because the bike is so big and would drag parts every turn. Of course he blew me away once the track straighten up!

Bluetooth OBD2 Adapter FOR KTM Duke 200 390 RC200 390 | eBay

That's really cool. I will try to find that for sale somewhere (that listing says its gone now) and try it out. Thanks for the idea!

Don't believe there is a limp mode on these.

Talked to my dealer at the track and he suggested it was going into Limp Mode. He has an RC390 too. So that's what I'm going with for now haha. There weren't any error codes or lights coming on so who knows. I should probably get some device to data log my ride sessions, as Simpletty mentioned above.

Check the spark plug cap under the fuel tank as it's known to come loose on the RC 390 causing the ignition to cut out at random.

I'll check the spark plugs. Thanks for the suggestion. The bike didn't completely shut off while I was riding though. Electrical was completely fine. Restarting the bike didn't have any problems either, it started right up.

Thanks to everyone for your responses. I'll try to update this page when I find out more.

 

[Ryanthegreat1]

Unfortunately that is the nature of the small bikes running with the big bikes. The big bikes use their horsepower to mask their skill set, very annoying to get stuck behind one of those riders. Blast it wide open on the straights and then throw out the anchor way too early and take a terrible line through the corner(s) and just barely tip toe through. All while holding up the bikes with a good line and good corner speed.

 

[EnCee]

Tee a fuel pressure guage into your fuel line and see if the pressure drops markedly under high revs/load. thta hsould confirm if it is a fuel issue. If it does change fuel filter, check tank venting or maybe pump/ pump relay.

 

[Bagwell]

Did you happen to notice the temperature level on the dash when this was happening? Wondering if the bike was running too hot at the time.

 

[thezidane]

This was my first guess but in all the excitement/confusion of losing power and trying to safely get my bike off the track I didn't get a chance to really look at what could be going on. I know the bike tends to run hot and being my first day on the track I did feel like I was mis-shifting a lot on the straights resulting in over-revving. Hoping it just needed to cool down.

 

[thezidane]

Just updating this for "completedness". Had a chance to check out my bike again after getting home from vacation. MIL was not on. Attempted self-diagnostic procedure of (a) holding the throttle open, (b) turn the ignition on, (c) held throttle open for 5 seconds, (d) and then closed the throttle. No blink codes.
I rode the bike for my very hot (95 degrees F!!) track day last weekend and it ran great. I am concluding the bike overheated or was getting mis-shifted too much at my previous track day and flipped into safe mode.
Thanks to every one so much for all of the help. Hopefully this can help someone with a similar issue in the future.