Chain Tension varies with wheel rotation

Hi, hope someone can help, I have a ZZR250 which ever since I have had it makes a whiring noise. Tensioning the chain last night I discovered what it is, the cahin can be correctly tensioned, but as the wheel rotates, the chain tensions considerably then llosens back to the correct tension. I am guessing this means something is bent but not sure. Any suggestions?

Thanks
Ben

could be a bent rod where the front sprocket bolts on to. More likely tho it sounds like you have a tight spot on your chain. i recommend replacing it immediately along with front and rear sprockets to avoid any further damage to the seals inside the gear box.

Once you have changed that, check for the symptoms and make sure they have dissapeared

worn gears and/ or chain ...maybe a 'frozen' chain would be my diagnosis
also possibly a stuffed cush drive (allowing the rear cog to move around)
a close inspection of these will tell the story
btw
when was the last time the chain was serviced....cleaned , lubed and correctly tensioned?

not too sure - the chain actually gets tighter though, it is not a case of the wheel simply getting tighter to turn. I oil my chain every 500kms (ie once a week) and have only tensioned it once and did this according to the manual. I do know the previous owner dropped the bike though but on the right side (he assured me he didn't but the proof was there)

thanks
Ben

My money is it's new chain and sprocket time. It does sound like a chain that's stretched and has some seized links. Hopefully the "whirring" sound isn't a sign of damaged bearings already. (I didn't know the ZZR250 had a cush drive.)

Thanks, I will give the chain a change - although the sprockets aren't worn so here's hoping

Thanks

Thanks, I will give the chain a change - although the sprockets aren't worn so here's hoping

Chains and sprockets wear in together. I think most people would recommend changing them as a set. There is the risk of shagging the new chain on the old sprockets.

Thanks, I will give the chain a change - although the sprockets aren't worn so here's hoping

Chains and sprockets wear in together. I think most people would recommend changing them as a set. There is the risk of shagging the new chain on the old sprockets.

+1
couldn't agree more

chain + sprockets..

chain + sprockets..

Quick learner.

BTW, my guess would be a tight spot. New chain & sprockets will fix that.

Do you plan on doing it yourself? You WILL need some special tools to get the chain on (more so if its a rivit link - recomended but not a necessity on a 250 IMHO as long as its regularly inspected)

Last edited by Phil on Tue Nov 17, 2009 6:57 pm, edited 1 time in total.

chain + sprockets..

definitely on a ...ZX12R

Ben all chains have tight spots in them . When you do a chain adjustment rotate the wheel until you find the tightest spot and do your adjustment from that .Another little trick is once you have the adjustment done place a allen key or screw driver between the chain and the top of the sprocket and turn the wheel backwards to pinch the screw driver between the chain and sprocket then tight'n the axle nut . Give the wheel a few complete spins once all is tight to double check it's ok , then take it for a test ride You can pull in the clutch at about 60 kph and feel if the chain is smooth on the sprockets