Chain tension

[Paris]

Hey folks ... what sort of tension should there be on a chain, ie how much play should there be when you move the chain up and down..?? Just want to check that mine isn't too loose, without having to take into the workshop ..

[cs363]

There should be a sticker on your chain guard or swingarm showing the correct tension for your particular model, if you have an owners or workshop manual it should be in there too. However failing that, the norm is usually around the 20-25mm mark measured midway between the sprockets on the bottom chain run. But some bikes vary due to differing designs.
If you google it you could probably find a few good maintenance websites with this kind of info, maybe even a specific site to your model. meantime here's one I quickly found: http://community.livejournal.com/mot...s/2302750.html

[Shadows]

the norm is usually around the 20-25mm mark measured midway between the sprockets on the bottom chain run.

Presuming you are talking about a road bike like a CB250 and not a dirt bike or similar with heaps of rear suspension travel - usually they have to have a bit more slack in them.

Make sure you check it in more than one position, as chains get tight spots, so what is okay in one place may be incredibly loose in another. ie: turn the back wheel a bit and check again a couple of times.

Don't catch your fingers between the sprocket and the chain when rotating the wheel because it really fucking hurts and the blood gets everywhere. I know this.

If tension is okay, see if you can pull a chain link more than a couple of mm away from the rear sprocket at its most rearward point. If you can, you need a new chain as it has been overstretched. Quite possibly new sprockets would be needed too.

[xwhatsit]

Make sure you check it in more than one position, as chains get tight spots, so what is okay in one place may be incredibly loose in another. ie: turn the back wheel a bit and check again a couple of times.

Just to clarify this so you don't get the wrong end of the stick -- that 20-25mm (or whatever the figure should be, sounds about right though for a 250 Hornet) should be measured at the tightest spot. Having a loose chain is much more desirable than having an over-tight chain (even in one spot), as when the suspension compresses and the chain tightens up you don't want to be putting heaps of pressure on the gearbox output shaft and bearings.

[cs363]

Presuming you are talking about a road bike like a CB250 and not a dirt bike or similar with heaps of rear suspension travel - usually they have to have a bit more slack in them.

I'm assuming he's referring to the CB250 Hornet in his profile, hence the road bike specs and link. But yes, for dirtbikes add some slack

[Shadows]

Just to clarify this so you don't get the wrong end of the stick -- that 20-25mm (or whatever the figure should be, sounds about right though for a 250 Hornet) should be measured at the tightest spot. Having a loose chain is much more desirable than having an over-tight chain (even in one spot), as when the suspension compresses and the chain tightens up you don't want to be putting heaps of pressure on the gearbox output shaft and bearings.

True, that.

You better writer than me is.

[Racin Jason]

Dont forget that many bikes have different swingarm pivot points in relation to the front sprocket, which changes the way the chain tightens. Some chains actually get looser as the rear suspension compresses.

If your ever unsure, (or dont have an owners manual) push up and down on the rear suspension and make sure there is at least some slack through the full range of travel.

[FROSTY:Me]

Chain hasn't fallen off yet has it? Come on over here and I'll show ya how to tension the chain on YOUR bike correctly.
Basicly given its the profile bike I would make sure theres 20mm of slack at the TIGHTEST point on the chain.