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I have A 2014 CBR500r & at extremely low speeds I can feel I can only describe them i guess as “rough spots” when In gear. Also at a certain rpm & it seems to happen in every gear (that I can hear at least) there is a vibration type noise made. It is definitely something to do with my transmission because the noise doesn’t happen when you just rev the motor out of gear. I believe the “rough spots” don’t happen either when out of gear or clutch is engaged. Even idling sitting still you can hear a difference when you engage the clutch and let it idle & whenever its not engaged idling. This is my FIRST BIKE & I got it with only 500 miles on it & it currently has 4000 miles. It has been down & I had to replace the shifter peg & a few other components when that happened In 2018. I’m thinking it’s just the clutch needing changed But I haven’t noticed it slipping but maybe once and that could have been my fault? I’m not sure though and I usually do things myself & don’t know of any trusted bike mechanics around me. I’m sure I could find one but I enjoy doing it myself, but don’t want to fix or order parts I don’t need to lol any thoughts or insights much appreciated and I live in pigeon forge, Tennessee
 

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I have A 2014 CBR500r & at extremely low speeds I can feel I can only describe them i guess as “rough spots” when In gear.
Noises with mere subjective descriptions of characteristics are really difficult to diagnose; can you get an audio or video clip with good quality sound?

How low a speed are you thinking here and in what gear?

Is it possible you're just lugging the engine? In a parallel twin like the 500 after one cylinder fires the 2nd one fires 180 crankshaft degrees later and then there's a gap of 540 crankshaft degrees -- one and half turns of the crankshaft -- before the first cylinder fires again. At very low engine speeds you might actually feel the pause in the duh-duh ---------- duh-duh... firing intervals and interpret as rough spots or even misfires.

Make sure you're doing any such roughness testing with the engine spinning at 3000RPM or more so the gaps in the firing intervals doesn't muddy the observations.

Also at a certain rpm & it seems to happen in every gear (that I can hear at least) there is a vibration type noise made. It is definitely something to do with my transmission because the noise doesn’t happen when you just rev the motor out of gear. I believe the “rough spots” don’t happen either when out of gear or clutch is engaged. Even idling sitting still you can hear a difference when you engage the clutch and let it idle & whenever its not engaged idling.
When you hear this in every gear are we talking very low RPM, in gear with the clutch engaged (lever released)? That part of the firing interval where the crank doesn't see a power stroke for 1.5-turns can unload the gearbox and primary drive, opening up on their backlash, which is then suddenly taken up again on the next power stroke. This can result in a feeling of juddering, roughness and even noise, especially when you factor in not just gear backlash in the engine but chain slack too.

When you're in neutral and hear a different level of noise with the clutch lever released versus lever pulled in, that's likely also normal. The transmission is always in mesh so when the clutch lever is released (clutch "engaged") the gears on the input and output shafts are all turning freely. The gears have backlash and that long period of 540-degrees with no power stroke can lead to the gear teeth bouncing against their backlash, creating some normal level of noise...

For the sake of completeness:

  • is this an obviously new condition? you haven't heard this before and it's way too obvious to miss now?
  • what is the condition of the chain? slack, tight links, lubrication etc?
  • condition of the sprockets?
  • how does the transmission shift? up and down through all gears; finding neutral?
  • how does the bike feel when being ridden normally? accelerating up through the gears with the engine churning above 3000RPM? any skipping, feeling of roughness or non-smooth acceleration?
 

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Discussion Starter · #3 ·
Noises with mere subjective descriptions of characteristics are really difficult to diagnose; can you get an audio or video clip with good quality sound?

How low a speed are you thinking here and in what gear?

Is it possible you're just lugging the engine? In a parallel twin like the 500 after one cylinder fires the 2nd one fires 180 crankshaft degrees later and then there's a gap of 540 crankshaft degrees -- one and half turns of the crankshaft -- before the first cylinder fires again. At very low engine speeds you might actually feel the pause in the duh-duh ---------- duh-duh... firing intervals and interpret as rough spots or even misfires.

Make sure you're doing any such roughness testing with the engine spinning at 3000RPM or more so the gaps in the firing intervals doesn't muddy the observations.



When you hear this in every gear are we talking very low RPM, in gear with the clutch engaged (lever released)? That part of the firing interval where the crank doesn't see a power stroke for 1.5-turns can unload the gearbox and primary drive, opening up on their backlash, which is then suddenly taken up again on the next power stroke. This can result in a feeling of juddering, roughness and even noise, especially when you factor in not just gear backlash in the engine but chain slack too.

When you're in neutral and hear a different level of noise with the clutch lever released versus lever pulled in, that's likely also normal. The transmission is always in mesh so when the clutch lever is released (clutch "engaged") the gears on the input and output shafts are all turning freely. The gears have backlash and that long period of 540-degrees with no power stroke can lead to the gear teeth bouncing against their backlash, creating some normal level of noise...

For the sake of completeness:

  • is this an obviously new condition? you haven't heard this before and it's way too obvious to miss now?
  • what is the condition of the chain? slack, tight links, lubrication etc?
  • condition of the sprockets?
  • how does the transmission shift? up and down through all gears; finding neutral?
  • how does the bike feel when being ridden normally? accelerating up through the gears with the engine churning above 3000RPM? any skipping, feeling of roughness or non-smooth acceleration?
I will try to get an audio clip in the next few days, i doubt I’ll have a chance tomorrow. The “rough spots” could very well be the cylinders like you mentioned, i don’t recall Feeling it any faster than 10mph usually around 5mph. The noise is definitely a new sound and you can’t miss that it sounds unlike it did before it started, and you can’t mistake it starting. I just adjusted the chain & lubricated in August. I’m not sure what you mean by tight links, I’m still learning everything lol the front sprocket was changed last year & I went down a tooth. I have a new back sprocket I haven’t put On just yet but it the teeth on it are good. It seems to shift fine & drive normal as it ever has, just that noise that’s different. I’m not sure the rpms It starts at. Thank you so very much for the insight and thorough explanation and questions of things. It’s very very appreciated
 

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I’m not sure what you mean by tight links...
Each link in the chain is connected to two others at pin joints. Each of these pin joints needs to be able to pivot smoothly and easily. If lubrication within the pin joint is lost (e.g. an O-ring tears and goes missing and the lube leaks out) or corrosion gets in (e.g. you use a power washer to clean the chain and get water into the joint) the joint no longer pivots easily. When it the chain runs 'round the sprockets (esp the smaller diameter front sprocket) those joints that don't pivot well -- those "tight links" -- will cause the chain to momentarily tighten and vibrate and make noise.

Tight links can usually be spotted by inspection. As an example, this image shows a few on the bottom run of the chain (and a half-tossed O-ring for good measure...):

 

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I’d put money on it being the chain.
 

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Very thorough responses here. I have 9500 miles on my '17 CB-500f (bought new in April, 2019) and have experienced no vibration problems even running (light throttle) as low as 2000 rpm. It's one of the smoothest engines I've ever had and, believe me, I've had lots of them! I'd look at the chain, as Blackfin suggests.
Ralph
 
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