Chain tension variation problems

[Guest telboy]

I need to share my experience with trying to eliminate tight and slack points on a chain with my newly acquired NC750x dct bike that has done 11,000 miles.

The variation was 30mm at tight point and 40mm at slack point. I decided to replace the front sprocket and chain ( DID 520 ZVM-X chain JTF 1373-17 sprocket) as rear sprocket showed no signs of wear.

 

After fitting I still had the same chain tight and slack points?

Further investigation revealed that the chain had a tight spot every 180 deg turn of rear wheel which meant that the rear sprocket was running eccentric. So I decided to replaced the rear sprocket and the result was the same?

This led me to the conclusion that the rear sprocket was not a good fit on the wheel hub and needed to be centralised on fitting, as you could move the sprocket on the hub before tightening the 5 locking nuts ( about .005 ins of play, same on original Honda one)

 

Having some 3m foil tape, I placed this in four places around the side of the hub making a good tight fit and centralising the sprocket. This worked and now the chain has the same tension in all places.

 

My conclusion is that I replaced the original chain and sprockets unnecessarily and the problem was with the tolerances of the rear sprocket not being close enough.

[SteveThackery 3,090]

Excellent detective work, there!

 

I would have been sorely tempted to shrug and say "Sod it, don't care".  

 

 

Edited June 15, 2018 by SteveThackery

[Tex 36,817]

Oh well, Terry, look on the bright side. You now have a new chain and sprockets and know they’re correctly fitted. So you can ride off into the sunshine with a warm glow of achievement.  

 

It’s not unheard of to have an eccentric rear sprocketalthough replacement normally affects a cure, (maybe those other folks just got lucky aligning the new one?). Either way, well done and thanks for posting.

[alhendo1 3,043]

Great job....my NC was like this and I just put it down to the poor quality oe chain and lived with it....I'll bear this in mind for my CB....👍

[MikeBike 5,005]

Welcome to the forum. See you're local, maybe see you around. I'm on a silver 2015 NCX with two vertical LED running lights

[Guest machinman]

7 hours ago, telboy said:

I need to share my experience with trying to eliminate tight and slack points on a chain with my newly acquired NC750x dct bike that has done 11,000 miles.

The variation was 30mm at tight point and 40mm at slack point. I decided to replace the front sprocket and chain ( DID 520 ZVM-X chain JTF 1373-17 sprocket) as rear sprocket showed no signs of wear.

 

After fitting I still had the same chain tight and slack points?

Further investigation revealed that the chain had a tight spot every 180 deg turn of rear wheel which meant that the rear sprocket was running eccentric. So I decided to replaced the rear sprocket and the result was the same?

This led me to the conclusion that the rear sprocket was not a good fit on the wheel hub and needed to be centralised on fitting, as you could move the sprocket on the hub before tightening the 5 locking nuts ( about .005 ins of play, same on original Honda one)

 

Having some 3m foil tape, I placed this in four places around the side of the hub making a good tight fit and centralising the sprocket. This worked and now the chain has the same tension in all places.

 

My conclusion is that I replaced the original chain and sprockets unnecessarily and the problem was with the tolerances of the rear sprocket not being close enough.

Genius

[Wierpig 32]

I've got the same issue.10mm difference in chain tension with a brand new quality chain and sprockets every wheel rotation correspondent to a paint mark on the rear sprocket.loosened the sprocket nuts in situ and re tightened.much improved but when I get time I will remove the wheel and try the foil tape trick! 

[Grumpy old man 4,673]

Reminds me of this