1 reply to this topic

[preston-7]

Hi, I know technically its not a zcars project, but i guessed someone in here would be able to help. right, here goes

I have a mini minus, and a 99 R1 yamaha yzf engine. and both subframes.

Im now wanting to put a sprocket onto a diff.

I'll be running 13" wheels, and im wanting to use the yamaha speedo... what size of sprocket will i need?!? if it doesnt matter then id like the smallest available because i'm very limited on space in my engine bay, does anyone have any ideas or help??

thanks

Nick

[R1mini]

Hello Nick,
You need to decide your top speed first, also tyre sizes I'm assuming 175/50 13" which is the standard mini 13" tyre.

To keep the sprockets as small as possible use a 14 tooth front sprocket, which is readily available, a 45 tooth rear sprocket will give you a top speed of 130mph, 46 tooth 127mph, 47 tooth 124mph and so on. As you can see the rear sprocket is large even using the smallest front sprocket available and I know space is extremly tight in even a normal mini including height which will be an additional problem for you. To have sensible gearing there just will not be enough room to run these large rear sprockets, if you don't want to extend the front end by 5" that is and even then the carbs and filter will be out of the bonnet.

I think that the pro motive kit is probably your easiest way and possibly only way of getting it all in

You can use the original clocks but the speedo readings will be way out, you can use a speedo healer or something similiar to recalibrate your bike speedo

Cheers
David