Q. When I spin the back tyre of my Honda CG125 in neutral I can hear a rumble and sometimes when I change down gears and don’t blip the throttle to match engine speed I get a “clanking” noise like the chain is slipping on the sprocket.
I have set the chain tension to 20mm on the centrestand as it says in the manual, but this noise can’t be normal?
Divetime, MCN forums
A. It sounds like you have overtightened the chain and a tight chain does more damage than a slack one.
Before you readjust the chain, check the condition of thefront sprocket, if the teeth have become hooked, or someone before you has flipped the sprocket round to get more mileage out of it, that will have those symptoms.
Once you are sure the sprockets are in good condition, set the chain tension.
Do not check the chain for play on the centrestand, instead identify if there is a tight spot on the chain, a good way to do that is roll the bike backwards. Once you’ve sussed it out, position that tight spot midway on the bottom run between the front and rear sprocket.
Then have the bike balanced on the sidestand and somebody sat on the bike with both feet up to take up the slack in the suspension. You should aim for a minimum play of 30mm and a maximum play of 40mm.
I hope you haven`t knackered your gearbox output shaft so check your front sprocket first and check for play in that shaft, or a noisy bearing.