Rattle / Knocking pulling away From a Stop

Hi,

I get a knocking sound when accelerating hard away from a stop. The belt is not due for replacement, it was done at 18,000 miles, the bike has now done 25,000.

I don't think the rollers have ever been replaced, could they be the cause.

Thanks

This problem has been a can of worms for some time now. mostly it turns out to be 'belt-slap'. It can sound quite nasty sometimes. If it sounds more like metal-on-metal then it will need a looking at.

All sorts of 'DIY' problems can cause this trouble;

Rollers/Sliders, Ramp plate, Drive Pulley Boss, Sticky Clutch, Driven Assembly Bearings and cleanliness inside the belt cover...to name but a few.

If you haven't already, type some key words into the search bar. If you are DIY then get in there and have a look around. If you need help getting in there, we're all here to help.

Does the glazing on the clutch pads cause rattling? I recall the roughness on acceleration (don’t remember knocking) and did the 5 second procedure to correct it and it’s been fine since.

Procedure: Start bike, hold front brake only, gas it to ~ 2500 rpm only for 5 seconds (while standing still) or so and see if that smooths out the knocking and roughness- it’s worth a go and won’t cause any harm as you’re only doing this for a very short period of time (you’re not frying the clutch pads to the point of failure).

If the above doesn’t help, then you might be in for a little inspection work- I agree, your rollers might be flat spotted, but I don’t think that would cause the issue you have - we have many experts here (me not being one of them)- if you’re ultimately tearing into it, consider a roller to slider swap (and there’s plenty of threads about doing that- it’s quite easy). 26 gram sliders from Dr. Pulley seem to be favored if you’re using the stock variator and rear drive spring (that’s my current setup).

Just as an aside. Green7, if you don't have a FSM, terrier has one for sale in the UK.

Just an extra footnote.

Sliders are quieter than rollers in general, but lighter sliders or rollers will increase noise over OEM 28g rollers.