Front sprocket play

Took GaGa up Dr Petes tonight for some TLC - going to change back wheel bearings and stuff because of this annoying rattle / grind

we noticed a bit of play on the sprocket shaft - in/out about 5mm or so - is this usual?

its not the sprocket or the sprocket bolt /washer - as they are both new - its the actual shaft

any suggestions?

Not good

Eh... Dr Pete had no answer
No idea mate Google it....

Play on the sprocket shaft can be caused by incorrect chain tension. The chain would of been run too tight for a long period.

I'm not familiar with the design of the crm engine but on some bikes it can be a relatively easy fix, usually a series of bolts around the shaft, remove the shaft and install a new bearing.

However some bikes you will have to totally strip the engine/gearbox to be able to replace it.

It's quite a common issue on the Honda transalp and Africa twin. Both bikes require an engine rebuild to replace shaft bearing.

Just measured the end play with digital calipers, and its coming out around 1.05mm.

Cant find any end play figures in ktm manuals, but googling it comes to 0.1-0.3mm is acceptable, and would be consistant with the end play on my 12 450, but this is a different generation motor, so cant really compare.

there is 0mm side to side play.

is there anyone with a RFS motor that could check what endplay they have or know what the upper tolerance would be?
And would this be a worn spacer? Cant see it but worth checking,


More worrying is that I just dropped the oil and am seeing this ammount of metal on the magnet after circa 300miles since last service.

[You must be registered and logged in to see this image.]

I know mine gets a few little bits, but nothing like that, but again a different gen motor, either way I'm getting the definate feeling the motor needs a teardown :/

curl666 wrote:Play on the sprocket shaft can be caused by incorrect chain tension. The chain would of been run too tight for a long period.

I'm not familiar with the design of the crm engine but on some bikes it can be a relatively easy fix, usually a series of bolts around the shaft, remove the shaft and install a new bearing.

However some bikes you will have to totally strip the engine/gearbox to be able to replace it.

It's quite a common issue on the Honda transalp and Africa twin. Both bikes require an engine rebuild to replace shaft bearing.

sorry - i should have said its on my KTM 450 exc '04 RFS engine

and the chain has been run a bit tight recently i fear

I've got a Ktm 450 exc in the garage. I can inspect the front sprocket shaft on Thursday or Friday evening, if you don't have an answer by then.

I've owned a 2003 450 exc rfs and a 2005 400 exc rfs both bikes would have a grey metallic sludge on the drain plug. I'd usually service every 10 hours.

curl666 wrote:I've got a Ktm 450 exc in the garage. I can inspect the front sprocket shaft on Thursday or Friday evening, if you don't have an answer by then.

I've owned a 2003 450 exc rfs and a 2005 400 exc rfs both bikes would have a grey metallic sludge on the drain plug. I'd usually service every 10 hours.

Sound thanks, would be a great help.

Do you get metal shards like that and to that amount after 10 hours on yours?

crm250dude wrote:and the chain has been run a bit tight recently i fear

Since mizzed has updated with a bit more info, a tight chain would affect side to side play on the shaft.
He states you have zero side to side play. So less of a worry in my opinion.