School me on gearing and derbis

Wesley Ambrosini /

So I have a flat reed, ported stock, malossi springs, stock spring, hack n weld techno circuit, 12 grams in weight. I'd like to get a little more top end out of it. What I'm scratching my head at is how gearing and variators play together.

In my head you can adjust the weights to match the rpm / acceleration to the the gear ratio, which really only effects the final drive.

Re: School me on gearing and derbis

Yep

Re: School me on gearing and derbis

DrGeorgeTompson (Alan) /

but derbis have a chain and sprocket final drive

Re: School me on gearing and derbis

Taller Gearing (larger front sprocket) means your variator will have more range in the top end at the expense of a slower shift in the bottom end. I have found on variated bikes that lower gearing will actually help your bike over rev better and make use of more higher rpm power at full variation. Mostly the only reason to gear your bike out is to not rip too hard and take it easy with a high torque set up that won’t rev out anyways. I had a pp with a eurokit and it had the almost the same top speed with 19 and 21t front sprockets, but the 21 was a more sustainable ride as it wasn’t screaming 10k all day. It definitely is something to mess with on high powered bikes, but on a stocker gearing is not the way to net speed gains. Get those files out and open up the exhaust port and the skirt on the intake. Maybe a boost hole on the piston if it doesn’t have one. Get a better pipe and a 19mm carb/intake too. Circuit pipes on Derbi is trash.

Re: School me on gearing and derbis

Wesley Ambrosini /

Nice this some good knowledge. I like the novelty of the circuit right now but I've been rocking a Puch treats pipe that revs out better. The piston is totally chopped as well as the intake window. I'll look into finally getting those port timings and do some more porting

Re: School me on gearing and derbis

Wesley Ambrosini /

I should add that I'm running a 14 front sprocket.

Re: School me on gearing and derbis

Kevin McDonald /

Varistor on Moby original 1978 seems to not rotate when pedaled but turns when turned by hand from mag side ,have selector on motor could be belt or ? Clutch slipping?

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