LCGB Forums

i have some gear ratios that i need to find out the speed at say 6k rpm on a 10" wheel then the same on a 12 " wheel .

here are the ratios

primary 1.96 (66/31)

1 1.529 (26/17)
2 1.263 (24/19)
3 1.047 (22/21)
4 0.869 (20/23)

no need to know how much power is needed or pipe, as we have more then ample. a change of sprockets will be needed on the primary so factor this in aswell

cheers simon

This may help? https://www.scooterhelp.com/tuning/lam.gear.calc.html

Norrie Bodge wrote:This may help? https://www.scooterhelp.com/tuning/lam.gear.calc.html

no good as you can only use the pre selected lambretta sprockets and gear ratios. thanks anyway . simon

Anyone??

Tape measure and calculator.
Should be formulas on tinterweb.
David Blyth posted them up on the old forum once.

Scooterlam wrote:Tape measure and calculator.
Should be formulas on tinterweb.
David Blyth posted them up on the old forum once.

yes , thought someone had posted a gear calculator somewhere was it avtone ?? will google it . thanks

Den08 wrote:https://avantone.wordpress.com/

That's the one, but it's no good as that too has pre set common gearbox ratios. Cheers Simon

https://www.blocklayer.com/rpm-geareng.aspx

Try this.
You'll probably need to measure wheel diameters, tyre profiles will make a difference.
Possibly a case of swapping diff ratio for primary ratio.

Found this site in 30 secs on Google.
Look outside the very small world of scooters.

Scooterlam wrote:https://www.blocklayer.com/rpm-geareng.aspx

Try this.
You'll probably need to measure wheel diameters, tyre profiles will make a difference.
Possibly a case of swapping diff ratio for primary ratio.

Found this site in 30 secs on Google.
Look outside the very small world of scooters.

I did look outside the box, as the gears are not scooter or lambretta. Thanks for the link. Cheers Simon

a-teamlambretta wrote:

Scooterlam wrote:https://www.blocklayer.com/rpm-geareng.aspx

Try this.
You'll probably need to measure wheel diameters, tyre profiles will make a difference.
Possibly a case of swapping diff ratio for primary ratio.

Found this site in 30 secs on Google.
Look outside the very small world of scooters.

I did look outside the box, as the gears are not scooter or lambretta. Thanks for the link. Cheers Simon

had a go with this one and its very good easy to use, only one problem you cant input sprocket sizes any lower than 18/30 . will have to find another lol. cheers simon

There should be a simple mathematical formular available somewhere.
You have most of the information.
Play around with the ratios you have divided by sprocket ratios ie 15/45 =3 multiplied by revs multiplied by circumference, times 60 should give you distance travelled in an hour.

I could be wrong with this but it shouldn't be hard to work out
The formular.

What's the engine gearbox out of and what's it going in.

Mike Abbey (I think this is right) recently put a ktm 300 in a scoot there's some stuff on face book and the guy gives the sprockets he used on there.
Hope this helps.

Scooterlam wrote:There should be a simple mathematical formular available somewhere.
You have most of the information.
Play around with the ratios you have divided by sprocket ratios ie 15/45 =3 multiplied by revs multiplied by circumference, times 60 should give you distance travelled in an hour.

I could be wrong with this but it shouldn't be hard to work out
The formular.

What's the engine gearbox out of and what's it going in.

Mike Abbey (I think this is right) recently put a ktm 300 in a scoot there's some stuff on face book and the guy gives the sprockets he used on there.
Hope this helps.

i was cheif engineer on the prior viscount and was built in my workshop ,2007 ktm 300 exc electric start was the donor bike. has electronic gear shift and also ignition interupter on the up shift, no clutch needed. mick made the exhaust and did a great job . we have more sprockets now and might have to machine the rear hub down to get the sprocket on as the chain is now riding on the hub. did 105mph on a gps speedo and could pull more.


as for my engine , its an mth 680cc single cylinder 2 stroke water cooled power valve and 4 speed manual , around 80 bhp . as we know there is no substitute for cc . donor scooter yet to sourced . cheers simon

found this gear calculator , lets you input all your own info .

http://woodsware.aciwebs.com/gears/

cheers simon