The perfect gearing solution for Big Paul??

[monkey boy]

Right,my mate Big Paul seems to be having some grief with his gearing and he's asked me to give him a hand sorting it out.
Engine is sx200,sh20 carb,42mmclubman li125 gearbox(possibly a special)on 18 and 47 tooth sprockets giving a final drive of 4.8.
The problem he is having seems to be its going flat in 4th gear,running out of steam maybe?
Anyway he's not known as Big paul for nothing,he's a hulking great big bugger that weights in at 17-18 stone and more often than not he has the other half on the back,luckily she's only small though probably less than 8 stone.
So what would people advise on the gearing?I have had a suggestion on going back to standard sprocket set up for this box ie 15,46 giving a final drive of 5.6.In doing this would it mean he'd have to rag the tits off it just to get it moving?
Any suggestions or advice would be much appreciated.
CHEERS AL

[drunkmunkey6969]

4.8 is no good for a big lad inc Mrs etc, but moving from 4.8 to 5.6 in one go maybe too much, and a bit OTT. Top end would probably be all revs and no speed.

Try 5.2 first, see how it goes, and take it from there. Move to 5.4 if still no good.

16/48 on a 125 box or 18/47 on a 125 Special Box gives 5.2

[monkey boy]

Thanks Dan
5.2 is what everyone seems to be saying
Was looking for confirmation.
CHEERS AL

[Avantone]

Why not have a play with this visualiser if you have Excel on your computer.......

http://www.tonycassidy.com

[fajes]

I'm 16 stone and I run a 5.2 (on a 225).