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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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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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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.
 

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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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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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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.
 

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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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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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I have the issue in 1st gear as well, the same was for my Honda Ruckus which is a single cylinder as well. It wasn't so much from being lean, it's just the nature of the motor. My ruckus was tuned perfectly using a wideband. (that doesn't mean it won't help, but it won't remove the problem completely.)
 

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I think you guys are better off getting a "proper" fuel controller, jerkiness will be a thing off the past!
 

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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.
Yeah pretty much this. It takes a bit of messing around with the throttle/clutch but after a bit of practice you learn the right balance of clutch riding and throttle.
 

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I today did a test and regain speed from 15Km/h in 3rd gear without use the clutch and no jerking happened. Using Rapid Bike Easy.
Luis
 

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Another option is "Tamer Throttle Tube" from G2ergo. Mine was part # 40-4H-HYK.
Labelled for several Honda and Kaw models, but rep told me it would fit the Duke 390. He
was right.

And it eliminated about 98 % of the lean surge and driveline snatch. Recommend it highly!
What a difference. I can ride now at 3500 in top gear without feeling as though I'm going
to get bucked off. Actually don't very much, as the engine vibrates more there. But it can
be done.

Cheers, John
 

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Is this the opposite of quick action tube?
Someone else mentioned?
Seems quick action would make more jurky but claimed otherwise!
Regardless it seems to be lack of fuel for emissions causing it, different throttle tubes are just masking issues.
Akra remap or fuel controls fix issues very well .
 

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Mine was the same until I bought a bazzazz controller, with a map for K&N airbox. Much smoother, but still doesn't like pulling from low revs.
 

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I am not really concerned about the jerky nature of the bike at certain speeds and gears, but am trying a higher octane fuel to see if that has an effect. So far none....
 

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I am not really concerned about the jerky nature of the bike at certain speeds and gears, but am trying a higher octane fuel to see if that has an effect. So far none....


That only fixes knocking conditions and helping to prevent it from blowing up, running a higher octane fuel won't fix air fuel ratio or lean conditions.
 
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