My bike (a KTM Duke 200) has poor acceleration at low engine speed (from 2000 to 4000 rpm) in every gear, but after 4000 rpm is the acceleration is normal.
What could the problem be?
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I suggest checking the spelling in your question and also what do you mean with "pickup"?– GrannyCommented Oct 19, 2017 at 7:42
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2To those looking at this question, I'm assuming English is not the native language, so please be patient when reading questions such as this. Please help a new user so they can get the assistance they're asking for ... I appreciate it! To the OP: Welcome to the Site!– Pᴀᴜʟsᴛᴇʀ2 ♦Commented Oct 19, 2017 at 13:18
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1@Pᴀᴜʟsᴛᴇʀ2 I have alot of patience with non native speakers, I am a non native speaker aswell but the whole question does not make sense to me. So rewording the question is a must at this point.– GrannyCommented Oct 19, 2017 at 13:26
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1@Granny - Completely agree and appreciate your patience. Leading questions may help in this case so the OP understands exactly what we need to help them out. Details are a bit shy, so helpfully the OP will get back with us and we can go from there. I just didn't want a ton of people jumping on the downvote bandwagon and shying the user off before they even get a comprehensive question asked.– Pᴀᴜʟsᴛᴇʀ2 ♦Commented Oct 19, 2017 at 14:06
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1I actually understand what OP is trying to say(I think). The question is about why the acceleration is not constant across the RPM band.– ranaCommented Oct 19, 2017 at 14:12
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2 Answers
What you are describing is not a problem. That is how internal combustion engines works.
The torque/hp of the engine is not constant across the RPM band. My guess is that your peak torque is after 4000RPM for that particular engine, which is why you feel like acceleration is lower when the RPM is below 4000. I'm not an expert in this subject, but check out the answers for the following question for more details: What is the difference between torque and horsepower?
Note: This is assuming the behaviour has not gotten worse recently compared to what it was from out of the factory.
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I've had this happen where an engine seemed to have almost no power until a certain RPM was reached. It wasn't normal. I never found the cause, so I don't have an answer to post, but I suspected it was a carb problem.– JPhi1618Commented Oct 19, 2017 at 14:25
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@JPhi1618 For some engines, that's just how they run. For example, I ride a sportbike with the redline set at 12.5k RPMs. It doesn't even start to make real power until about 5k or so, if you just let the clutch out and start rolling at idle and then open the throttle, there's a good second or two before you start accelerating at any useful rate. From experience I can say most sportbikes are pretty much the same in that way.– CeshionCommented Oct 19, 2017 at 14:34
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@Ceshion, yea, I get that but in this case there's a difference in "not much power" and "man, something is wrong and the engine is gonna die if I twist the throttle too much". My bike didn't do that before - something happened.– JPhi1618Commented Oct 19, 2017 at 14:39
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@JPhi1618 ooh, definitely. carbs are always a good candidate for that one– CeshionCommented Oct 19, 2017 at 14:42
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images.motorcycle-usa.com/photogallerys/… for reference for the post, here's a dyno sheet showing the torque curve of a ZX6-R to illustrate the original point, notice torque doesn't start increasing consistently until about 5.8k RPMs– CeshionCommented Oct 19, 2017 at 14:44
it is normal- that is how the engine runs . I had a KTM 690 single that was only usable in the upper half of the rev range. Single cylinder 4-stroke engines are often lumpy and uneven at low rpm depending on application
