I discovered a bit of a problem with my 3C during the resent Snowy Ride in OZ.It seems my bike is doing 1000 revs more at the same road speed as a couple of other Laverdas in top gear,120 Jotas both.My bike is running std sprockets,19x 40 but has a low profile rear tyre,140x60,there is no other option in aspect, that measures 625mm dia and 2000mm cir.The 120 Jota I measured is running a 120x90 and is 660mm dia and 2145 cir running 16x34 gearing.I love the tyre,huge grip,no stand problems and nothing drags with enthusiastic cornering so its staying.I am a bit rev restricted till the jetting is fully sorted,6000rpm and the 3C has a fairly big gap between 1st and 2nd so if I go a bit smaller on the rear this wont get any better till i can use full revs.Has anyone used a 38 on the rear of a 3C and what effect did it have on exceloration,do you reckon I would get the 1000rpm back with that change and not loose to much tow out of corners,the motor is very strong.BTW what happens when the Suzuki wheels are fitted re tyre profile.
Gearing Problem
- Thread starter Vince
- Start date
Vince said:
Vince,
I'm currently running a 150/60 tyre on a 4" Suzuki rim with 19/38 final gearing on my old 3C. Bike runs, well, OK I guess. Tops out at a shade under 8500..... you can compare road speeds with the excellent speed/gearing chart on Laverdamania.
http://www.laverdamania.net/chart.htmDon't see 1000 revs difference just because of the tyre section, seems a bit much to me. (too lazy to calculate right now!)
piet
Dellortoman
Hero member
- Location
- Tasmania, Australia
I wouldn't be putting a lot of faith in the accuracy those old ND instruments. Watching my bike's tacho when it was on the dyno the other week, with steadily climbing revs in the acceleration test, the tacho went up to 6000, back to 5000 (while revs still increasing) then jumped to 7000 and continued on up from there 
I don't stare at the tacho when I'm riding, so never noticed it before.
Cheers,
Cam
I don't stare at the tacho when I'm riding, so never noticed it before.
Cheers,
Cam
andychain
Hero member
Vince 38 tooth will do the job fine. The first thing I have done on my Bandits is take 2-3 teeth of the the back. Takes fuel consumption to 120 miles per tank from 100 and the front comes up at 28mph instead of 24
Andy
If you cant get a 38 sprocket ask your local bearing guys for a 10B-1 platewheel with 38 teeth and get it machined. It will be in steel but can be lightened dramatically.
Andy
If you cant get a 38 sprocket ask your local bearing guys for a 10B-1 platewheel with 38 teeth and get it machined. It will be in steel but can be lightened dramatically.
hi
revving at a higher speed does not necessarily mean higher fuel consumption,as well as our laverdas my friend and myself both have triumph sprint st's.i use a one tooth smaller front sprocket as used in the daytonas,i get better acceleration and at 80mph I'm revving 500rpm faster,yet my fuel consumption is allways 1 to 2 litres better on each tank fill.it used to be the same before the change to within a few pence so its not a discrepancy in instruments.
this is the same road conditions riding down to Italy and doing all the passes Austria,Switzerland,Slovenia,and also to Prague,so this has been long term.pisses him off when i allways put in 2 to 3 euros less petrol than him
neale
revving at a higher speed does not necessarily mean higher fuel consumption,as well as our laverdas my friend and myself both have triumph sprint st's.i use a one tooth smaller front sprocket as used in the daytonas,i get better acceleration and at 80mph I'm revving 500rpm faster,yet my fuel consumption is allways 1 to 2 litres better on each tank fill.it used to be the same before the change to within a few pence so its not a discrepancy in instruments.
this is the same road conditions riding down to Italy and doing all the passes Austria,Switzerland,Slovenia,and also to Prague,so this has been long term.pisses him off when i allways put in 2 to 3 euros less petrol than him
neale