Well ordered a plus 2 17t if it fits and a plus 1 16t as well. Arriving tomorrow so I can check shaft at the same time. Will post on results 

First ride out today. I did tension chain to 50 mm when fitted new as of Haynes manual (Sorry thinking of the bandit 1200n) Its the rear sprocket that has worn teeth. Tensioned again sprockets not arrived yet. I expect tomorrow 

Oh it broke down at sainsburys cheadle on the roundabout. Luckily it was out of super unleaded! Fuel tap on reserve setting now leaks as well.  It was fine in November when I last rode it! Good to be on him again. 

wonder how many there are in our area, I know of only 3 yours mine and one in Dukinfield

I saw one on bonis hall lane on my way to macc about 3/4 yrs ago. Was a couple of riders with him. Thats the only one ive ever seen 

They have arrived. Not a lot of clearance between swingarm roller and sprocket 

Well the 17 tooth is fitted. It just fits. 

The 15 is here which I had to get the windy gun to remove 

It now clears the top of the swingarm chain roller with the 17 tooth just. 

 

Well went out for a first blast today since sprocket change. All I can say is wow! I can keep the front wheel on the ground and where I would have been in sixth gear from the lights I am still in 3rd with the 17t front sprocket. Gear changes are about 6-8 seconds apart. The swingarm roller seal guard is not touching the chain anymore and is smoother ride. That was brand new when fitted and has been busy looking at the grooves in it. No play or oil leaks detected in shaft. Probably if I adjusted the rear shock to softer it would have given the same effect. Feel like it's an Rd200 but with knobblies on. Dont forget im 1.50 oversize and energy induction fitted too. 

It now feels like I could ride it for longer distances without fighting it all the time. 

Revs to speed in top gear. 30 mph is 3000 rpm, 50 mph 5000rpm. Can hold it on an incline under the powerband. 

90 is 9000 rpm.

So I assume it wasn't you who hammered the shit out of that poor bloody nut holding the front sprocket on! They got no spanners where you bought this from Simon? Just cold chisels and a lump hammer engineering.

Schoolboy no tools 1970s mechanics! They did the same with the steering head nut. The guy who bought it brand new (now passed away) forgot to put 2 stroke in it. It sat since 1980 after a rebore in Ashton which the guy didnt chamfer the ports. Rings broke after 15 mins running. Because the sprocket nut was original I thought I would keep it.