Stalling problem in a brand new bike.

[Maddog Reynolds]

I only just saw this. I don't have much experience of KTMs, but it sounds as though it runs rich and stalls, then needs lots of spinning over to restart because the inlet and cylinder are flooded with fuel.

My road bike does something similar, but only when cold and only if I pull away gently. It misfires and stalls and it's difficult to restart. Also I it will stall if I give it a rev to 6,000 rpm and let it drop to idle before it is warmed up.

In my case I think it's before the Lambda sensor warms up and the ECU is running open loop. It seems to me KTM often start with injection set a bit rich to be on the safe side.

 

[KTMGene390]

I believe the problem is simply due to the bike running too rich. I have Dynojet's WB2 with a digital gauge so I'm able in real-time to see the AFR just before it stalls and this happens at 2-5% throttle and it's running 11:1, sometimes richer just before it stalls. It does the same thing even in neutral the difference is when you have the bike in gear and have a load there's not enough power so it stalls. Also, turning the key off and on fires the bike right up otherwise it takes a long time to restart. I have long since learned to ride around the problem so it rarely affects me anymore.

Of course, since I have Chad's engine kit with the intake ports being larger there is less air velocity at lower RPMs which makes it much worse and I have to learn to ride around that issue too. This is pretty standard for a race engine build requiring a higher idle, longer warm up and more clutch slippage to get going at part throttle, but once above 4,000 RPMs it climbs over other RC's.

Btw, with the previous mods I had the Bazzaz Z-AFM, and looking at my laptop screen it did the exact same thing both kits use the same wideband O2 sensor. I also have the Akra ECU flash and I believe it makes it much worse until you learn to ride around the problem. If you are having serious stalling issues then other factors are to blame in addition.

 

[Diploman]

On the Duke forum there was much discussion of the stalling issue. One forum member, Hoover, was having a stalling problem similar to the one described here. He surmised that the stalling behavior might be connected to the sidestand cut-off switch, which interrupts the ignition circuit when there is inadequate magnetic force from the sidestand magnet to close the switch (ie, when the stand is extended).

Hoover first cleaned both the magnet and switch carefully, then installed a washer on the sidestand to position the magnet closer to the switch when the stand is retracted. Presto!! The stalling issue disappeared. Many on the Duke forum have now applied this simple fix, and discussion of stalling issues is now rare. I am not asserting that the sidestand switch is the cause of all 390 stalling problems - fuelling or other issues may be involved as well. However, it has been definitively discovered that the sidestand switch, when isolated from the sidestand magnet by dirt or distance, does indeed create mischief that appears to be the source of many stalling problems. Before going into analysis and speculation about AFR, etc., I suggest applying applying Hoover's very simple sidestand fix to eliminate this as a potential cause of stalling.

 

[KTMGene390]

On the Duke forum there was much discussion of the stalling issue. One forum member, Hoover, was having a stalling problem similar to the one described here. He surmised that the stalling behavior might be connected to the sidestand cut-off switch, which interrupts the ignition circuit when there is inadequate magnetic force from the sidestand magnet to close the switch (ie, when the stand is extended).

A long time ago I had a cell light which turned out to be the sidestand switch upon inspection it had a glob of chain lube on it, I now regularly keep it clean. I haven't had a problem since, but I would be curious for a link as that is a mod worth performing anyways. I have tested my bike on the rear stand and the same issue appears my bike is definitely running super rich everytime this happens only in the 2-5% throttle range but mainly between 2-4%, if I hold the throttle steady at 2% it runs rich continuously until the throttle openings go above 5%. This was exactly the same case even with just an airbox and exhaust mod previously. I have not tested this on a stock bike, my suspicions is you would get the same behavior since most likely it's related to the ECU mapping.

 

[kayabusa]

Regarding the side stand switch, I have the cup version , it doesn't came with a side stand...... but is the switch still there ?

 

[KTMGene390]

Hey guys, my happiness and joy of the new bike turns out quickly to worries...

I got my brand new 2015 Cup Bike, 3 days ago.... I put the battery on charge the whole night, check the engine oil, the coolant and in the following morning I put gas on the bike and I started.

I Left the bike idle in the rear stand for about 10 minutes, no issues with the temp, all good , but I do notice that the engine wasn't idle perfectly. So I decided to take it for a spin.

The first 300 feet was ok but as soon as I hit the corner when I was downshifting the bike stall..... I'm 44 years old and I ride bikes for the last 38 years.... said enough... Anyway, ok I dont know the bike, my mistake, lets try it again.

Next corner when I was downshifting and I rev it a little bit and we are good for the next one.... but in the next corner the bike stalls again..... and again... and again.

I left the bike alone and came back today to check it and it was way worse.... here are a couple of the videos that shows exactly the problem.

Second Run: https://youtu.be/Y_F5FBIlwVY

Third Run: https://youtu.be/XcVXRC0pVnA

Pretty bad !! I don't want to go to the dealer yet, maybe is something I can fix with the help of you guys.

If someone has any ideas please share them with me.

Thank you.

Just watched your YouTube videos. This problem goes beyond the scope of normal stalling issues at a light. I bought the street version so I don't know if the cup version has an emission canister. If so, did you remove it? Also check your air box for cracks which will cause a vacuum leak. A pinched fuel line or clogged fuel filter is also suspect. Next, I would be looking at the voltages of the TPS, as a bad sensor can cause those issues too. I assume you still have this problem even with pump gas?

 

[Diploman]

KTMGene390, as requested, here is a link to the sidestand fix discussion, with photos.

http://www.ktmduke390forum.com/forum/issues-troubleshooting/26850-stalling.html

 

[KTMGene390]

KTMGene390, as requested, here is a link to the sidestand fix discussion, with photos.

http://www.ktmduke390forum.com/forum/issues-troubleshooting/26850-stalling.html

Thanks, I will look into this.

 

[HolyJeansMan]

I know I'm late to the conversation but I had the same issue with my bike with zero miles on it. Tried to bear with it in hopes of it just being rough to break in. Drove it to work and my transmission seized and can't shift. Clutch may have to do with the issue that started with the stalling. Had wife get trailer and taking it back to the dealer here in GA.

 

[kayabusa]

I know I'm late to the conversation but I had the same issue with my bike with zero miles on it. Tried to bear with it in hopes of it just being rough to break in. Drove it to work and my transmission seized and can't shift. Clutch may have to do with the issue that started with the stalling. Had wife get trailer and taking it back to the dealer here in GA.

My dealer didn’t help, so I fix it myself but I replaced so many parts that I don’t know where the issue was originated..... Also I use the bike only for trackdays, the engine has 6 hours on it ! (around 300 miles city commuting)

Good luck with the dealer
they are a key factor on solving the problem quickly.


Sent from my iPhone using Tapatalk Pro

 

[Seth]

Let me get this right. You bought a 2015 bike in 2017 right? That would mean the bike has been sitting for 1.5 to 2 years? In theory this shouldn't be an issue but maybe contributes to the sum of the issue?

 

[HolyJeansMan]

A really jacked up spark plug.... That was what they said about the stalling. The transmission seize was because the screw that secures the shifter rod vibrated out and the linkage fell off. When put back on it was just barely off and was binding when trying to shift. But now its running great. Made sure they rode it several times before I picked it up and rode it myself before leaving the dealer.

 

[Edwardp33]

I had a stalling problem because my plug wire was unseating

 

[John390]

just adding some info incase someone is searching later. I know this can be a problem with these bikes.

I have played around with a few things to cure this.

I have ridden a 2017 for a test ride and it stalled probably 10-15 times all at slow to medium speeds, all in traffic. Kind of scary to be honest. My brand new 2018 bike did it as well, but no where near as much. Bone stock it did it probably 2-3 times a week using about 10-15 kilometers a day riding in city traffic. however, sometimes it did it 2-3 times a ride...

My hypotheses are two fold

First, the high compression single cylinder engine with very lean mixtures, having a closed throttle and a clutch pulled in, will have the rpm drop from 5+ thousand rpm to idle or less in a very short time. its a single so if there is one whiff of a misfire due to lean mixtures or the timing not being correct very briefly, a stall could easily occur.

We all have lots of anecdotal evidence of richening up the mixture really helps this problem. I added a Rapidbike Evo and played with the map a little before I uploaded it to the bike. Tweaked it in a few spots I saw as "flat". Bike was immediately better and got even better still over the next few days as the thing learned its new map.

Way better, but still not perfect. it would still stall occasionally. Enough that it was annoying, but not enough that I was prepared for it. Like, once a week or week and a half. Still about 10-20kilometers a day. Ride to and from work in traffic and ride after work in the area around my town.

So, onto the second part of my hypothesis. When I would stall it would sound like something "caught" briefly. Sort of a snatchy clunk. Sorry, crappy description, but its a noise It sounded to me like something was briefly slowing the engine down to under the rpm that would stall it. I know that it always happened when I pulled the clutch lever in and got off the throttle, to come up to a line of traffic at a light or something like that. So I tried adjusting my clutch lever to the fullest travel. I also observed that the clutch lever on the trans end would move more with full travel on the hand lever and less with shorter travel. This got me to think that maybe if the clutch wasn't fully disengaging, it might be a drag on the engine.

So I carefully adjusted the lock nuts on the cable end to be sure I had full pull on the lever. I made sure that I had free play, as I know that you need some. I then took up the slack with the adjuster on the hand lever and made sure I had the mandated 2mm of travel up there when the lever was on full reach. This gave me the most lever movement on the transmission end of the cable. Double checked that I had free play and played with clutch bite point in the driveway so that I knew I was safe on public roads.

Well, lo and behold! NO MOR STALLING AT ALL!!

Its been probably 500-1000km, pretty much all city and outlying area riding too. Lots of opportunity for it to act up. It has not.

I have added an aftermarket set of adjustable levers and readjusted the cable when I did so. Zero problems so far, but I am going to go out on a limb and call it fixed.

I fully trust it to not stall in traffic anymore.