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Strange noise coming from 2019 scorpa twenty


Nukeproofmule
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Kinda metallic rattle coming from my 2019 scorpa… anyone got any thoughts what it could be? Videos make it sound worse than it is but it’s still annoying. 

-I thought it might’ve been the chain, but don’t think it is now as I’ve put a new on and still the noise
-doesn’t make the noise with clutch in freewheeling over rough ground 
-just had rear linkage and shock bushes replaced so i don’t think it’s that either

A bit stumped on this one so any thoughts appreciated!

Cheers

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Also what width of chain did you put on. Ive seen people put mx chains on and the width has caused the split link to hit the chain tensioner arm

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Thanks for the replies…

I’ll have a look to see if the chain is showing any signs of catching anything, aye it’s a Regina 520 trials chain that’s on it. 
to begin with I thought it sounded like the chain but I can’t understand why the noise would disappear with the clutch in if it was🧐

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16 hours ago, Nukeproofmule said:

Thanks for the replies…

I’ll have a look to see if the chain is showing any signs of catching anything, aye it’s a Regina 520 trials chain that’s on it. 
to begin with I thought it sounded like the chain but I can’t understand why the noise would disappear with the clutch in if it was🧐

The noise disappears when you pull the clutch in because that takes the tension out of the chain which allows the chain to move under the effects of gravity and inertia rather than being pulled into a straight line by the motor. When the clutch is out, one run of the chain is tight and the other is loose - under motor drive the top is tight and the bottom is loose. Under overrun, the bottom is tight and the top is loose. When you pull the clutch in and ride along, both runs are loose and the chain flaps around more.

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From that short clip the rattle seems a touch intermittent? Is the master link catching on something? As advised above it certainly sounds chain related, could the wheel be installed any straighter? 9 second video of that is making me want to figure it out!

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19 hours ago, feetupfun said:

The noise disappears when you pull the clutch in because that takes the tension out of the chain which allows the chain to move under the effects of gravity and inertia rather than being pulled into a straight line by the motor. When the clutch is out, one run of the chain is tight and the other is loose - under motor drive the top is tight and the bottom is loose. Under overrun, the bottom is tight and the top is loose. When you pull the clutch in and ride along, both runs are loose and the chain flaps around more.

Ahh okay that makes a lot of sense actually…I can’t see any clear signs of the chain catching any metal on the frame or swing arm though. 
Only thing i did notice is that the outside faces of the chain links look polished from what I think must be passing through the tensioner block. 
The tensioner arm has a bit of side to side movement and is quite easy to push up down. Maybe both of these are contributing to a nasty noise?

@Glaynehaha yeah it’s bugging me too, chain & wheel seem to be nicely in line and spin freely with the bike in a stand. 

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How about putting the bike on a stand and applying tension to the top run then to the bottom run. Apply the chain tension by putting the bike in gear and rotating the rear wheel back and forth. The idea of this is to replicate the conditions when it makes the noise

You are not looking for the chain catching on anything. You are looking for a spot where metal can touch metal. Possibles include a worn chain guide at the front end of the swingarm or a worn chain tensioner block. Is the tensioner hitting the swingarm?

Edited by feetupfun
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3 hours ago, feetupfun said:

How about putting the bike on a stand and applying tension to the top run then to the bottom run. Apply the chain tension by putting the bike in gear and rotating the rear wheel back and forth. The idea of this is to replicate the conditions when it makes the noise

You are not looking for the chain catching on anything. You are looking for a spot where metal can touch metal. Possibles include a worn chain guide at the front end of the swingarm or a worn chain tensioner block. Is the tensioner hitting the swingarm?

Ah yeah so I did try this the other night when bike was in the stand but couldn’t hear much. 
That’s a good point about the front chain guide being worn through the plastic and catching metal. I’ll need to take the chain off and have a good look. 

cheers

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  • 2 weeks later...

@Glayne @feetupfun

Not sure if you guys are still interested but I’ve found where the noise is coming from. Chain is clacking off the bottom of the rear sprocket. 
I have the chain tension set so the top of the tensioner block is about 20mm from the under side of the swing arm but might try a bit tighter to see if the noise goes away. 
do the chain tensioner arm springs wear out over time and need replaced? Chain guide does also seem to be sitting at a slight angle so it’s maybe taken a bash off a rock at some point 

EDAF3ABB-08EF-48C2-A0FB-504174C7A126.jpeg

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Good find, I would start getting the chain guide straight or replaced. I would imagine just about any spring gets fatigued over time, I have not had to replace mine...yet...

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