sprocket / chain combination advice

[mickdale]

just run in my lambretta and running an indian gp200 gearbox with 21 /46 sprockets on a 83 link chain.

i need to raise the gearing

can i run a 22/47 or 22/46 combination of sprockets and what chain length will i need?
will a 22 front sprocket fit ok in the casing?
where can i get a 22 tooth front sprocket?

any help greatly appreciated

cheers
mick

[J1MS]

I know it's not exactly the answer your after, but, what if you use an LI special box with more easily available sprocket and chain?

[mickdale]

thanks jims
i know the pacemaker box is supposed to have better gear ratios but more stress on the clutch? - ive only got a 5 plate

pacemaker with my 21/46 gives a 4.03 final drive as opposed to my 4.38

i was hoping to get slightly taller gearing

food for thought though
cheers
mick

[soullad]

Mick - what engine set-up you running? Sounds interesting...

[mickdale]

hi soullad
i asked harry barlow to build me a torquey touring engine and i supplied a casing, 20/47 sprockets and an indian gp 200 gearbox thinking they would be fine.
once it was built he took it out for 10 minutes then came back and said the gearing was no good - he put 21/46 sprockets in it but riding it round the m25 then up the a1 yesterday i decided i want to raise the gearing as i think theres enough grunt to take it

[Stokie]

hi soullad
i asked harry barlow to build me a torquey touring engine

What's the spec of the rest of the motor ?

[mickdale]

hello stokie
60mm crank ts1 230cc with pro porting piston, bgm reeds, 3mm packer, lth manifold, 30mm PHBH, machined base of cylinder bringing transfers from 33ish down to 27 degrees, widened exhaust port and radical transfers and pro porting stepped header 48mm clubman

i think the exhaust complements the setup allowing tall gearing as its pulling 4.38 up inclines no probs so want to try taller gearing (i live in east anglia which is flat and can cope with the gentle slopes/hills of the A1 no problems)

[GP Kevo]

Sounds like you have the gearing just right. Just because you live in the flatlands doesn't mean you're not going to go riding off into a headwind or worse, a mild grade + headwind. Not being able to hold a decent speed when doing that is the reason I started off into tuned engines in the first place.