Play in my driving sprocket

[Athame57]

I went to check my chain tension, that was fine but other sniffing around had me find play in my rear final drive sprocket. The four securing nuts are good and tight and the retaining circlip is in position, no play in the wheel either.
Before I pull everything apart though, will this be down to the damper bushes being worn out? 

[K2-K6]

Sounds like rotating play you're feeling there ?

If so, then it's the gear dog engagement you'll feel initially and above all other movements in that plane.

Visually, the dogs are like castelation (think Castle turret) with two sets opposing each other, to be moved into "mesh" intertwined in carrying the drive torque from one neighbouring gear to another on the same shaft ... all moved as you change gear.

There MUST be slack in their form to allow them to easily engage on request, else you'd need the accuracy of William Tell to fire them in between each other.

Essentially, fairly crude in arrangement with the slack you can feel if rocked back and forth. 

Technically these are a "constant mesh, dog engagement" gearbox design as are most bikes. It's the dogs you hear clattering in partially missed gear change is made, and not gear teeth as such. Pretty tough life, the dog's life in a gearbox

[Oddjob]

Reading that I got the impression he was feeling front to back motion in the rear sprocket not the front, hence the reference to 4 nuts, only 2 on the front sprocket.

If so, the damper rubbers may have gone hard and need replacing.

[Athame57]

Reading that I got the impression he was feeling front to back motion in the rear sprocket not the front, hence the reference to 4 nuts, only 2 on the front sprocket.

If so, the damper rubbers may have gone hard and need replacing.

Yes, it is rear sprocket.

[K2-K6]

I was going to say, I think you're right Ken 

Yep, rear cush drive rubber suspect then.

[Oddjob]

I'd remove the rear wheel and dismount the sprocket, then place each stub in the damper rubber hole and see if it moves.

[Athame57]

I'd remove the rear wheel and dismount the sprocket, then place each stub in the damper rubber hole and see if it moves.

I've just ordered a new set from Legend motorcycles on eBay, just £15.oo for a set. Well that's better than paying DS over £82.oo! 

[Sesman]

Really, a set? They are normally around £15 each!

[Mikep328]

Probably the difference between the genuine Honda part and a pattern part.

[Athame57]

Probably the difference between the genuine Honda part and a pattern part.

Julie confirmed they are aftermarket but the retailer is not a bad one so they should be ok. Time will tell. One thing I'm wondering though, is if the washer that sits behind the circlip is still there, I'll find out when the workshop take off the sprocket.
If it is missing, well they were the last people to have been that far! That part seems to be unobtainable (?) as a bit of exploration so far fails to produce a source for one. I hope it is there then.

[TrickyMicky]

You must be bleedin' phsychic.  I have just put my GB250 in for MOT this afternoon, and it failed on there being no shim/spacer behind the circlip on the rear sprocket!!!!  I'm fortunate in that DSS is only 25 minutes ride away from me, and he has managed to locate two for me in about 10 days.  £10.30 inc. VAT. CMSNL only have 1 and they want a fortune for delivery. Funnly old world ennit?

[TrickyMicky]

BTW, the washer/spacer on the 400 is part no. 41202 28 6000,  and CMSNL in Holland have them listed as available.

[Bryanj]

What section of the test did it fail on? Wouldnt even have been an advisory in my day

[Athame57]

You must be bleedin' phsychic.

Well, I don't have a crystal ball, they don't work anyway, but us Wiccans do tend to see some things coming!    I just rechecked the CMSL site and they can only offer to let you put it on your watch list, ie they have none.
I hope my one is in position but I'm being lazy, I'll see when I get the other bits I'm waiting for.

[TrickyMicky]

What section of the test did it fail on? Wouldnt even have been an advisory in my day

  Rear sprocket classed as excessively loose as attached (hopefully).  The shim/spacer is fairly thick. It was the most thorough MOT test I have ever been to, but the man let me stand next to him and he explained fully everything he did. Will definitely use again.  As they say that confession is good for the soul, I feel obliged to tell you that on returning home, I emptied out the container marked "250 bits" and guess what was in there!!!.. Severe wrist slapping is due.