GY6 on a Hobbit; a different approach.

My Hobbit's driven pulley was pretty gnarley inside. The ramps were all chewed up and it was starting to stick open. So, I decided to do something with one of them GY6 driven pulleys.

I didn't really want to put a clutchless variator on my crank and do all the complicated stuff to the gearbox to get the GY6 clutch working, so instead I machined a little spacer thing with the correct taper to mate with the drive shaft taper on the gearbox. The spacer then mates up with the innards of the GY6 driven pulley once you have removed all the bearings. Welded the parts together, and it's on!

P.S. no that crusty shit gearbox is not on my hobbit; just a spare :) (edited)

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Re: GY6 on a Hobbit; a different approach.

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Re: GY6 on a Hobbit; a different approach.

nice work!

Re: GY6 on a Hobbit; a different approach.

Won't the belt get cockeyed from the front and rear pullies moving opposite directions?

Re: GY6 on a Hobbit; a different approach.

Yeah, that's a definite concern. I'll have to see what the results of that will be.

Re: GY6 on a Hobbit; a different approach.

Just cut a horizontal minarelli scooter motor tranny housing in half.

That would be cool, and the belt travel would be right.

Re: GY6 on a Hobbit; a different approach.

Oh, I just had an 'oh duh' moment. People are mounting their variators inverted in the front so the belt movement matches the back.

Re: GY6 on a Hobbit; a different approach.

RADIUM CITY JO$HUA /

The important thing is that you did it anyway.

Nice work.

Re: GY6 on a Hobbit; a different approach.

Now make 50 of them and sell them!

Re: GY6 on a Hobbit; a different approach.

Haha, ^ that is setting yourself up for failure.. Do more testing first

Re: GY6 on a Hobbit; a different approach.

ᴛᴇʀʀʏ ᴅᴇᴀɴ /

the hobbit's relatively long belt will probably not care about crossing up a little. there's only one way to find out!

Re: GY6 on a Hobbit; a different approach.

I was thinking too that I may re-bore the taper inward a bit more so the pulley sits a few mm inward at idle, thus making it so when it's fully variated it's only sitting a few mm outward; make the mid-range the 'straight' as that's where one likely spends most of their time.

I think I'll give it a try with a BX40 rather than my stock belt as I'd hate to destroy it on an experiment like this.

Re: GY6 on a Hobbit; a different approach.

Its a no no to have the belt off even a little bit.... You guys ever ride snowmobiles? The pulleys get shimmed!

Re: GY6 on a Hobbit; a different approach.

But how short/wide are their belts? That makes a big difference.

I don't think it will matter too much. Think about a peugeot or moby... The pulley stays in one plane and the variator causes the front plane to move. They have very little issues, even with a short belt.

Re: GY6 on a Hobbit; a different approach.

Alex Hedrick /

What taper angle is the input shaft? I planned on doing the exact same thing..

Re: GY6 on a Hobbit; a different approach.

It’s not great. Really.

They all wobble and they all break.

That kind of weight, and kinda unbalanced weight has no business locked onto the hobbit gearbox shaft. Top speed sucks shit, you vibrate all over.

Better to stick with the stock pulley for now.

Have fucked with these things for a long time and decided they just cannot be good runners. Great idea and they work fine on a bearing shaft but lock it to a shaft with a taper and it’s going to suck once you get ripping

Re: GY6 on a Hobbit; a different approach.

Alex Hedrick /

Jbot.. I know they suck.. lol but I want to make it good..

so turn the adapter out of some 4140 or whatever I have laying around. Maybe .005 oversize to the gy6 pulley bore, and leave the taper undersized to the hobbit shaft. Then chuck the gy6 pulley, skim the id to accept the adapter.. press it in, re chuck the pulley with the adapter pressed in it, indicate it in then run a finish pass on the taper to final size..

Might be over kill..

But I know what you are saying, I think this way I have a chace of getting it to run as true as possible..

Re: GY6 on a Hobbit; a different approach.

Unless you make a new pulley you’re fucked.

It’s the gy6 pulley that’s fucked. Not anyone’s machining of adaptors.

The horizontal minarelli pulleys are much better but again, they’re meant to rotate on bearings not be locked to a shaft.

Do what you do, but I’m telling you, you’re much better off modding the stock pulley.

Re: GY6 on a Hobbit; a different approach.

Alex Hedrick /

I know I know.. ill give it a shot.. mainly cause it sounds like fun to fuck with, im sure ill find out quickly that it just sucks and go back to the stocker modded out..

If worse comes to worse.. why not throw a Piaggio crank in the hobbit cases and run that shit.. with the clutch on the rear.. (not a fan of that, i think the clutch should be before the variation) maybe im wrong?

Whatever.. I love honda shit, endless possibilities!

Re: GY6 on a Hobbit; a different approach.

Dirty30 Dillon /

Honestly, jbots right.

They effective options are not stock, or go full rear clutch from Minarelli horizontal/Piaggio scoot with er3 front.

Re: GY6 on a Hobbit; a different approach.

The moto matic pulley was like this one that mars designed. It put too much pressure on the fixed cheek of the rear pulley and eventually broke it. Also there are the issues with alignment that were brought up. making a rear clutch work on a hobbit is as easy as using an urban express input shaft and grabbing a special seal. You can even make a one way bearing work if you make a spacer for an hfl1616. Naz helped figure all this out and did all the machine work to get the hobbit crank to work with a doppler var. He has done it a few different ways over the years and the last iteration was by far the best and easiest way to get oversized pulleys and a rear clutch.

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