I will say this before you go and rush out to find smaller rear
sprockets for any machine you might own.
of modifactions to a Shineray 125
is just a general guide.
If you are about to do your
own maintenance, using these pages,
I take no responsibility
if you get things wrong / if parts wear out faster or break!
I don't think this would have worked for a Honda, Suzuki or similar.
I certainly wouldn't try to do this to my RX1000, maybe a tooth
smaller, but we went down by 9 teeth in this machine.
I was asked to make this machine run a little faster.
When I first time I used the mechine I was getting 50mph (according
to this speedo) while the rev counter just under the red line, it was almost
impossable to make the thing go faster (down hill maybe or with a good
tail wind.... or both maybe).
|The Sprocket was
|The replacement sprocket, sat on top of the old one.
| I had to open the centre hole by 5mm to let the sprocket
sit peoperly on the wheel hub.
I knew it had to be central too. Otherwise the sprocket would
wobble when the wheel was turning.
Grinding 2.5mm out all around opens the diameter of the hole by 5mm
|The centre hole was perfect, but I still had to drill the four holes
for the bolt holes.
Finaly I shortened the chain by two full links.
| Then I used a centrepunch to mark the future holes, making
sure that when the holes are drilled the new holes lign up with the threaded
holes in the hub. I used a pillar drill to make the holes
Then fitted the sprocket
Tested it, now it got 60mph at the same revs.
I then decided to try to modify the main jet too.
I'd never tried doing this sort of thing, but I thought I'd try it
and if it didn't work.....
I would have just reverted it back to standard. I dropped the needle
circlip down by two notches.
It seemed to have worked
Now we get it over the red line both on speedo, and rev counter.