What about an automatic clutch?

[lingeringstin...]

Here I go again. I've been banging on about this for years to wails of "It'll never work!", which experience tells me means it will work just fine if I can only figure out a way to do it.

In a nutshell, my idea is to convert a normal geared motorcycle engine to some kind of semi-automatic clutch without costing a fortune. I'm sure it can be done especially as now there are loads of things like scooters and quadbikes that use some kind of automatic shenanigans.

I could never get my head around doing this to an MZ two stroke engine as it tends to go RINGGG-A-DINGGG-DINGG-DINGG and hang in higher revs while you're trying to change gears but now that I'm using a Honda clone four stroke engine it's got me thinking about it again.

I know Honda used to make automatics but that shit's out of the question because you won't find any of them to butcher for parts and I only want to use readily available stuff.

If you could simply replace the standard clutch in a motorcycle engine with some kind of centrifugal clutch thingy that grabs at certain revs and ungrabs at lower revs then you could shift gears as normal on the fly by simply letting off the throttle so the auto-thingy disengages momentarily to allow gearchange.

In theory that sounds simple enough but all the simple, cheap autoclutches I know of are dry clutches so the engine oil is a problem there. I don't know if there are any oil bath autoclutch designs but I'm researching it. If they don't exist or are too expensive then that might imply modifying the internal bike clutch to be a fixed gear and using an external centrifugal clutch mounted someplace else like where the alternator is now and somehow linking it to the bike gearbox. An alternator like off a Kubota or something could be fitted elsewhere, or I could have someone to run alongside the bike cranking a generator for me.

If you could fit a dry centrifugal clutch outboard of the engine somewhere and just use it in normal twist and go fashion then you could use the bike's internal gearbox like a hi-low axle. That way you could for instance use third gear for all nippy twist and go usage around town and fifth gear for highway use.

However, I fecking HATE the sound of twist and go scooters and I don't think it makes great use of the bike's gearbox anyway. I think that kind of setup could be sluggish and annoying. Having no experience of these things I don't know if they work fast or strong enough to be able to shift gears on the fly which is what I'm really after.

It does seem potentially doable with all the modern scootery, quadbikery and snowmobilery contraptions around nowadays to steal parts and ideas from. I can't really see why some sort of centrifugal clutch that disengages at low revs (yet to be determined) wouldn't work and there's probably something sturdy enough to take the massive throbbing horsepower of my 233cc four stroke Chinese engine (probably about as much as a tuned up 125 scooter).

I'm certain it can be done at not much expense, so I'd love any information and ideas please. Feel free to shout "It'll never work!" until you're blue in the face.

[stinkwheel]

Re-inventing the wheel I'm afraid.

https://rekluse.com/
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[lingeringstin...]

Unfortunately way too expensive for my tastes. Aimed at the Lazyfatbastard Newbike market.


HOLD UP!

I just spotted one of them that could be made to work on Ebay for about £250. That's getting much more like what I was after. Worth keeping an eye out for something like that.

[stinkwheel]

There is also the whole C90 setup.

Being honda based, some parts might even bolt right on?

You'd probably need to fanny about with spring tensions and such.

They probably use something similar in the innova.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Pete.]

[lingeringstin...]

To my shame I've never had a C90 or similar thing so I've never been into the clutches of them. I do know that the C90 racers do silly things to their engines and squeeze more power out of them so MAYBE a C90 clutch would work on my 250. I'm not making a race bike, but I do pull a trailer sometimes.

[lingeringstin...]

OK so I've just looked at C90 clutches and they're apparently actuated by the pedal. That's close but not what I'm aiming for. What I want is something that automatically disengages the clutch a low revs. I'm not completely ruling out the C90 clutch idea yet because it actually looks like a decent bit of kit but I was wanting to do away with any pedal or lever altogether.

A bit more problematic it that the C90 clutch has oil passing through it to the crank. I could run into fiddly oilway shenanigans with that design.

So far the Rekluse clutch with the ball bearings looks simple and effective, but expensive. In fact it looks like such a simple idea it's got me thinking about how to modify a standard clutch. It's all about weights and centrifugal forces and shit.

Time to don my mad scientist hat.

[jjdugen]

Must admit, in my 'blue sky' moments, its something I have considered too. I'm a little more radical. I can't see why a fully hydraulic transmission wouldn't work, especially on a motorcycle.
Consider. The main expense in a motorcycle engine unit is the gearbox, all those fine cut cogs, bearings, etc. Its limiting in that the gear ratios essentially decide the way the whole machine performs, and the engine is rarely within the absolute best parameter for performance and / or economy. So why not have the crank connected to a fluid impeller, linked by pipes to vane 'motors' in (both) wheels. All wheel drive, the transmission fully automatic, seamless power transmission.
Maybe a bit too extreme, we would need a bit of crowd funding for that project. You need a catchy name of course, always open to offers..... and a big donation.
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The CBR900RR has been sold. Aprilia Falco worms its way into my heart.
Try Soi 23 on Amazon for a good read.... Self promotion? Moi?

[stinkwheel]

The C90 is both a centrifugal auto clutch AND a pedal activated one.

So from neutral, you bang it down into first, take your foot off the gear lever then ride away like you would with an auto scooter. Second and third you just close the throttle and shift.

However. If you change down into first and LEAVE your foot on the pedal, this holds the clutch in. You can then wind the revs up, pop your foot off and do a wheelie.

It is properly auto though. You can stop in third and it wont stall. The old ones used to then cycle back into first from third so you could just stop in third change up into first and ride off again. They removed this feature on later models because too many people were changing into first at 50mph.

Works really nicely, just like riding a normal bike but without having to bother with the clutch. It's centrifugal but NOT constant velocity so it engages fully once you're moving rather than constantly slipping.

My understanding of the centre fed oil setup is it's a form of oil filter. It spins the oil out to the outside of the clutch casting and any muck gets trapped in a series of notches. I'd imagine it would work well enough being immersed in oil like a standard clutch.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[lukamon]

Nah. Later one were still a circular gearbox but they somehow enginerded it so you couldn't go from 3rd to N while moving.
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killa wrote: Im an ass man myself

[Chris45]

Seem to recall Honda did a 400 cc automatic back in the 1980's. Some sort of variation on the Superdream. However it may have been for the US market only. I suppose it's all to do with the market, whether there is enough demand to justify all the R&D and rejigging required to manufacture them.

Many years back I had a 2L car with an auto box, it was a doddle to drive and silky smooth but, oh so boring....
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Honda CG125>Suzuki GT185>Honda CB 250N>Suzuki GSX400>Honda CX500B>Kawasaki GPZ305> Kawasaki GPZ550>Kawasaki GPZ500S+BMW 650GS

[lingeringstin...]

[Robby]

I had a kymco k-pipe 125, which uses a C90-esque clutch setup. It didn't work well with the modest power increase from a 90cc to a 125, and changing down a gear in the wet was lethal. The clutch becomes a suicide clutch with very little travel, meaning the back wheel ended up skidding a lot.

Either go full auto with a CVT or go fully manual, you don't realise how much you appreciate fine clutch control until you don't have it.

[Pete.]

[lingeringstin...]

I saw a picture of clutch for a Kawasaki KLF300 and it looked just like the clutch on my Almost-Honda 250, so I started looking into it.

As far as I can tell from the pics the clutches are identical, as are many other bits I've seen between the two engines but the Kawasaki KLF is apparently a quadbike engine with an automatic clutch whereas my Quadzilla engine is basically a bike engine cobbled onto a quadbike.

Looking at pics the engines internals look very similar, so now I'm wondering if I could cobble a Kawasaki KLF quadbike clutch onto my Chonda engine. It would be interesting but a bit of work.

I suppose I could just get a Kawasaki KLF engine and fit it where the Chonda one is now, but where's the fun in that? It's much more exciting to make things really hard to do and overly expensive in the process.






Or I could fit a nice Ebay item like this:
302415617510