Front sprocket - worst case scenario ?

Oh dear, this does not sound too good. I'm not very familiar with the Bonnie and its little foibles, but I wonder if you can get some long nosed pliers into where the gearbox sprocket is and try to waggle it about (a technical term!) to see if it is loose. If it is that, I would try to get it to the nearest bike dealer of any persuasion to see if they can/will help you. If the sprocket did come off, it could cause the chain to fall off and possibly jam the rear wheel. Of course, it may be something completely different and not that important. As I say, I have no practical experience of Bonnies and it may just be something simple that's come a bit loose, but be careful with it until you can get it checked over. Hopefully a bit of 'summat and nowt'. Good luck with it!

 

If you suspect the nut is coming loose on the drive sprocket you must remove the cover over the sprocket and check. It will be obvious if it is loose, a tab of the locking washer should be bent over and against a flat of the nut. I would certainly not continue to ride, worst case is the chain comes off and jams the back wheel as well as smashing the drive case.
As a temporary fix you may be able to tighten the nut with an adjustable spanner if you are without a proper socket spanner and torque wrench, then use a screwdriver and hammer to tap the locking washer over the flat of the nut. You must then get it properly tightened and torqued asap. I would also check the drive chain for tightness, check the rear wheel is inline and correctly adjusted.
If you do a google search on T100 drive sprocket you will find a schematic showing the sprocket, nut and locking washer.

If its not the drive sprocket or chain check the rear wheel bearings by checking for any side to side movement of the wheel while on it's stand, check the wheel rotates freely for a full circuit of the chain. If in doubt use your European breakdown cover (hoping you have it!) get it checked and don't continue to ride. Hope you get it sorted, please let us know how it goes.

 

Yeah, agree with Richard H - have just replaced my 18 tooth with a 19 tooth sprocket, so now know this bit of the bike quite well. The tab of the locking washer, which is a pretty thick, should be flattened firmly against one flat of the nut, holding it in place. The nut should be tightend up to 132Nm. If it is loose you must get it tightened - an adjustable spanner should do it as a road side fix, especially if you can knock the tab of the washer down tight against it.

 

I wonder if you had a seized/tight spot in the chain. If so would expect it to make the noise by spinning back wheel off ground, no engine running. Seems a long shot tho? Maybe this would be sorted by oiling/spraying?
Just a hindsight thought if that chain were really dry? hope it goes well now. ps I did 19 tooth conversion as well.

 

Glad it was something that simple, probably need to lube the chain every 300 miles or after riding in heavy rain.

 

yep sounds like a couple of seized links, never good for the chain as it tightens and loosens all the time.

Keep an eye on it but it should be okay :smile:

 

As our bikes are of a similar age I'm not surprised that they are the same colour ,but I'm amazed that we appear to have the same stickers on the side panel!