Help swapping grear cogs if possible??

[chris2470]

I run and GP200 Indian box with a 18x47 on a Dave Betts race tuned 225 top end and is fitted with a Sterling pipe which is quite revy I think.
I confess I'm no gearbox expert in fact I have never touched one but was wondering if I could simply take my 3rd gear out and fit it with a 39 tooth one out of a LI150 or I think a GP125 in order to close the ratio form 2nd to 3rd. Also I may fit a hardened ScootRS 46 tooth rear crown wheel at the same time, this will give a final ration of 5.1.
Can anybody tell me if this is simple one out and one in job or are there other complications when swapping gears or are they all interchangeable.
I've used this top piece of software and all seems OK.
http://www.tonycassidy.com/microsite/Ge ... liser.html

[bristolmod]

basically seperate gears are NOT interchangable apart from a few rare instances. You have to change the whole gearbox and Christmas tree. Fine tuning should be done on the front and rear sprockets.

Chris

[chris2470]

Ok IC, thanks for the info. I might have know things are never that simply.