Jerking Issue - KTM Duke 390 Forum
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post #1 of 27 Old 09-11-2017, 11:47 AM Thread Starter
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Jerking Issue

Hi, I have completed 1200 km on my new KTM Duke 390 model and first service is done. I am facing a issue from the day one but the service guy says it's common in a high capacity single cylinder motorcycle. The problem is the bike jerks in low rpm, below 3000 - 3,500 rpm even in first gear. The feeling is like that the fuel is not coming to the engine but the problem disappears in high rpm. No problem in open road or highway. But it is irritating if I ride in traffic in slow speed. Is it the characteristic of Duke 390 or a problem with my bike ?
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post #2 of 27 Old 09-11-2017, 12:35 PM
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Originally Posted by Suman Dutta Mazumder View Post
Hi, I have completed 1200 km on my new KTM Duke 390 model and first service is done. I am facing a issue from the day one but the service guy says it's common in a high capacity single cylinder motorcycle. The problem is the bike jerks in low rpm, below 3000 - 3,500 rpm even in first gear. The feeling is like that the fuel is not coming to the engine but the problem disappears in high rpm. No problem in open road or highway. But it is irritating if I ride in traffic in slow speed. Is it the characteristic of Duke 390 or a problem with my bike ?
My 390 is the same. It's just a symptom of riding a thumper I think. I find I need to clutch this bike a tonne in traffic, and never go below 4k rpm. She's dead below that.
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post #3 of 27 Old 09-11-2017, 01:00 PM
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Same with mine. You gotta use the clutch to smooth out the ride at slow speeds.

All my bikes are single cylinders and I have the same issue in each to varying degrees.

Never give up.....
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post #4 of 27 Old 09-11-2017, 01:14 PM
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Quote:
Originally Posted by Suman Dutta Mazumder View Post
Hi, I have completed 1200 km on my new KTM Duke 390 model and first service is done. I am facing a issue from the day one but the service guy says it's common in a high capacity single cylinder motorcycle. The problem is the bike jerks in low rpm, below 3000 - 3,500 rpm even in first gear. The feeling is like that the fuel is not coming to the engine but the problem disappears in high rpm. No problem in open road or highway. But it is irritating if I ride in traffic in slow speed. Is it the characteristic of Duke 390 or a problem with my bike ?
Yes, powerful single cylinders apparently have that issue.
My DRZ-400SM was not that smooth too, for instance.

By the way, what about all those iconic Royal-Enfield thumpers over there?
Is Bullet 500 or 350 smoother at lower RPMs with their totally different characters?
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post #5 of 27 Old 09-11-2017, 02:32 PM
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Jerking

Hi,

I think itmight be something to do with the quality of petrol in India as I found youtube videos where 390 owners experienced the same problems and found that carbon had collected in the throttle body and caused irregular operation.
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post #6 of 27 Old 09-11-2017, 04:19 PM Thread Starter
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Thanks for your replies. So, it is a common issue. I will insist the service centre next time to clean the throttle body of the bike.

Suman
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post #7 of 27 Old 09-11-2017, 04:22 PM
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This is also often referred to as lean surge... the bikes run very lean. The Akrapovic map will help some as will a PCV or Bazzaz etc.

2016 Duke 390 - Lowered 45mm F&R with T-Rex Racing link and kickstand, YSS MZ506 shock, RC390 fork springs & custom spacers, DynoJet quickshifter and PCV, Gray Area KTM airbox, open lid, inverted K&N filter, Werkes pipe, TYGA header, 16T sprocket, 320mm Galfer rotor and HH pads, XHP50 LED headlight, Vizi-tec SupaBrake II, Renthal grips with HeatDemon heaters, lever guards, Ride It Moto levers, eBay sliders, rear spools and rearsets, DIY tail tidy, HD radiator, F&R shock guards, OBD2 dongle
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post #8 of 27 Old 09-11-2017, 04:49 PM
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390's just run super lean man. Aside from getting a fuel controller to richen up the low rpm fuel mapping, you could also get a G2 quick action throttle tube to help you adjust to opening up the throttle faster and not sitting in low rpms. Plus side is it will help you develop better throttle control since you'll be up higher in the rpm's and with a more sensitive throttle.

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post #9 of 27 Old 09-11-2017, 05:27 PM
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The only fix to it is use a fuell controller or a lambda sensor controller like Rapid Bike Easy so in Close loop it will run richer than stock and I would say it much much better beast at low/mid rev since Im using it.
BoosterPlug has the same target but I never use it. https://www.ktmduke390forum.com/forum...osterplug.html

Luis
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post #10 of 27 Old 09-11-2017, 06:36 PM
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Same here, but I already knew that it would do it. When I am splitting traffic, I chuck it in 3rd gear and cruise at about 35-40 kph (about 25 mph). This is about 4000rpm. Helps a bit because the torque curve is reduced due to the higher gear so you don't get the jerk as much when the ECU pumps more fuel in. Could probably cruise in 4th at that speed, but the throttle response is no good if you need to get out of trouble.
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