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Discussion Starter · #1 ·
I own a 790 and find it stalls/cut outs when going from 2nd to 1st gear. I had read a lot of information on it but there doesn't seem to an actual known fix for what seems to be a extremely common issue?

Bike is on 4000 miles with a booster plug installed. Having the booster plug installed has improve the snatchy throttle but has not altered the bike stalling etc.

Before that I had immobiliser failure, so bought a lithium battery and that fault has not returned since. So possible drop in voltage that the lithium battery does suffer with vs standard yuasa.
 

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I own a 790 and find it stalls/cut outs when going from 2nd to 1st gear. I had read a lot of information on it but there doesn't seem to an actual known fix for what seems to be a extremely common issue?

Bike is on 4000 miles with a booster plug installed. Having the booster plug installed has improve the snatchy throttle but has not altered the bike stalling etc.

Before that I had immobiliser failure, so bought a lithium battery and that fault has not returned since. So possible drop in voltage that the lithium battery does suffer with vs standard yuasa.
’Common issue’ according to who? Could be wrong, but I can’t ever remember it being discussed on this forum. Do you have any other mods apart from booster plug?
 

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Discussion Starter · #4 ·
When mine kept stalling I did a search a got loads of results of people with the same issue.

https://www.reddit.com/r/KTM/comments/vtdp2p
Just a few examples. Plus the immobilizer issue might be linked. TBH I have not had any stalls since installing a JMT lithium battery but only time will tell. It felt like when you go down from 2nd to 1st gear there was a lack of fuel and the bike just died, now with the lithium battery it seems more stable. Some people did say the lithium battery would help because it can regulate voltage better but it could be a placebo affect at this stage.
 

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Many reports of 790's and 390's(including mine) doing this. Was always thought to be due to lean condition but adding fueling device never quite cured it. I fitted a piggy back unit to my 390 for this exact reason but it still cut out regularly. I found that if I let the bike warm up a little more than necessary before setting out, it reduced chances of cut-out and a 790 rider reported that switching off shortly after take off and restarting, stopped his cutting out.
KTM(through dealer) tried sorting this issue on an Australian 790 owners bike as hers was quite extreme. They threw everything at it from injectors to 6 axis imu and eventually gave up. Swopped her 790 out for an 890.
So no....no definitive answer. Good luck with it.
 

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Mine had never done it before but after the 18k mile service it has done it a few times. Also the QS doesn't work as well and the fueling is not as clean. I also have the power booster and wondered if that affected their calibration any.
Has anybody installed the Akra map without changing the full exhaust system? I'm thinking about trying that out
 

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Many reports of 790's and 390's(including mine) doing this. Was always thought to be due to lean condition but adding fueling device never quite cured it. I fitted a piggy back unit to my 390 for this exact reason but it still cut out regularly. I found that if I let the bike warm up a little more than necessary before setting out, it reduced chances of cut-out and a 790 rider reported that switching off shortly after take off and restarting, stopped his cutting out.
KTM(through dealer) tried sorting this issue on an Australian 790 owners bike as hers was quite extreme. They threw everything at it from injectors to 6 axis imu and eventually gave up. Swopped her 790 out for an 890.
So no....no definitive answer. Good luck with it.
I went through to same issues with my 790. Initially stalling frequently on the slow down at traffic lights or similar then more alarmingly from 4th to 3rd on the tip in at speed. On each occasion shifting manually so this wasn't a quickshifter issue. Dealer did re calibrations, I search this forum for other fixes and passed them to the dealer but made sure everything was logged and in writing via email. In the end with a month or warranty to go (and continued silence from KTM factory) I told them the bike was a liability and they needed to come up with a favourable trade or buy back ie similar to the outcome noted above with another Aussie owner. In the end I upgraded to an 890R at a healthy discount as a compensation. So my advice is keep on the dealer and KTM and push them for support/compensation.
 
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