Psycho Scooter: A bad idea, 20 years in the making

This morning, while making my daily trek to the dump with a bag full of the previous evening's diapers, I spotted this little gem set off to the side of the trash compactor:

My good sense led me to move right past it and continue on down to the area where we drop off the recyclables. However, I suddenly had a flashback to a plan that had been pushed into a dusty corner of my brain many years earlier. I drove back up and threw the old scooter into the trunk of the Subaru.

On a shelf in my barn, I still have a Tanaka / Free Spirit two stroke bike engine that my father had bought new back in the late 70's. When I was about ten years old, we mounted it onto the 26 inch front wheel of my ten speed bike and it would do about 30 mph on the flat streets. Note the size of the drive wheel.

You can read about them here: http://www.users.globalnet.co.uk/~pattle/nacc/arc0394.htm

As a teenager, I dreamed of mounting it onto a bike with 16 inch wheels, but I didn't have the skills to do it. So, now I have this discarded scooter with its 12 inch wheels. With the Tanaka mounted to it, my calculations show that, while torque would be, approximately, Zero, after a few kicks of my foot to get moving, top speed would be, approximately, Insane, with a nearly subterranean center of gravity.

I suppose that the plastic wheels will have to go and I may extend the wheelbase and steering rake a bit for "stability". The brakes should be completely inadequate. I will discard the kickstand in the interest of saving some weight.

I wonder if they have a class for 23cc vehicles at Bonneville?

Keep an eye on CNN for news of my impending doom.

We'll give the Darwin Awards website a heads-up.

Cool project. You may be interested in this, guy local to me is building something very similar (albeit, with the motor hanging over the rear wheel) - http://www.ae86drivingclub.com.au/forums/showthread.php?t=178

It's already capable of over 40mph, but he's yet to run it with the modified engine, adjusted gear ratio, and small bottle of nitrous oxide

Aren't your gearing calculations a little backwards? I'm betting on a top speed in the 14mph range

Update.... college has fried my brain. New top speed: 30mph.

That is in fact accounting for the Canadian/US conversion rate

dan_efi wrote: Aren't your gearing calculations a little backwards? I'm betting on a top speed in the 14mph range

That sounds about right to me...

unless i'm totallly baked, won't the new top speed be the same as the old top speed? assuming engine RPM is the same, of course. you're driving the tread surface of the tire, right? and at another point on the tire, the tread surface contacts the road. so you're essentially driving the road, only with better ground clearance. the little wheels will be spinning (26/12) times faster than the big ones, but they're also covering only (12/26) times the distance per rev. so it all falls out in the wash.

Uhm... also college frying brain... but wouldn't the wheels be spinning the same speed, but covering less distance per rev (12/26), hence reducing top speed?

edit: yeah! bolting larger or smaller wheels to a hub doesn't make them spin any faster!!!

Pit Bike! I would keep the kick stand though, eventualy you have to stop and add fuel

AngryCorvair wrote: unless i'm totallly baked, won't the new top speed be the same as the old top speed? assuming engine RPM is the same, of course. you're driving the tread surface of the tire, right? and at another point on the tire, the tread surface contacts the road. so you're essentially driving the road, only with better ground clearance. the little wheels will be spinning (26/12) times faster than the big ones, but they're also covering only (12/26) times the distance per rev. so it all falls out in the wash.

I would have to agree, and not just because he used fractions either.

Uh, yeah. What Angry said. And Dan before him.

Bad-ideas-wise, though, it does look like there's clearance for a larger drive wheel on that motor. That would get you some (ill-advised) high speed.

2.0dohc wrote:

AngryCorvair wrote: unless i'm totallly baked, won't the new top speed be the same as the old top speed? assuming engine RPM is the same, of course. you're driving the tread surface of the tire, right? and at another point on the tire, the tread surface contacts the road. so you're essentially driving the road, only with better ground clearance. the little wheels will be spinning (26/12) times faster than the big ones, but they're also covering only (12/26) times the distance per rev. so it all falls out in the wash.

I would have to agree, and not just because he used fractions either.

having taken Dynamics.. X3 edit X4

that little drive wheel, provided its driving the tread, is the same as directly driving the ground. (the 2 contact patches have to be at the same velocity)

if you want to increase speed/decrease acceleration, put a larger wheel on the motor, if you want more accel, less top speed put a smaller wheel on the motor. as the previous poster indicated

the wheel size driven off the wheel on the motor (bike/scooter wheel) is inconsequential

Why let common sense and good judgment keep you from your dreams?

I say go for it.

Shawn

Hmm.... angular velocity isn't dependent on the radius/diameter of the wheel... but actual velocity is! So... different sized wheels will have different speeds at the same RPM (redline, top gear)

w=omega v=rw... so, (w) is the same, but (r) is smaller so top speed should be smaller. Will be a torque beast though

Stuc wrote: Hmm.... angular velocity isn't dependent on the radius/diameter of the wheel... but actual velocity is! So... different sized wheels will have different speeds at the same RPM (redline, top gear) w=omega v=rw... so, (w) is the same, but (r) is smaller so top speed should be smaller. Will be a torque beast though

The motor doesn't turn the wheel at the axel, it drives the wheel at the tire. So for a given speed of the motor the RPM of the wheel will vary with its diameter. They are right wheel size doesn't change the speed.

Its basicly like how an idler gear doesn't affect speed. The motor is one gear, the earth is another (really big) gear, the wheel is the idler gear.

Hey, we did one of those when I was a student at BCIT. We used a Pioneer chainsaw motor on a foot scooter and called it a Hardly Davidson. Only front brakes though - the other lever was used for the throttle control. Campus security didn't have a sense of humour about it at all.

G

All I have to say is, go ride the bike you already have sitting in the BARN arghhh, and you were worried about killing yourself on a motorcycle lol. little wheels and big holes= NO FUN, but seriously go ride that bike man.

Yeah, please post a youtube link to the vid of your first ride cause 30mph on a scooter may only happen once!

petegossett wrote: Yeah, please post a youtube link to the vid of your first ride cause 30mph on a scooter may only happen once!

It's not hard to get up to 30mph on a scooter...if you have a steep enough hill or the right powered vehicle to grab onto...

• Yes I really went more than that fast...and with a dinky roller blade wheel scooter too...nearly liquefied the rear wheel trying to stop.

wherethefmi2000 wrote: All I have to say is, go ride the bike you already have sitting in the BARN arghhh, and you were worried about killing yourself on a motorcycle lol. little wheels and big holes= NO FUN, but seriously go ride that bike man.

Admit it, you really want my motorcycle don't you?

If you do not, send it to me. Ill pay shipping! :)

I like this idea. I need some used Chainsaws.....

Woody wrote:

wherethefmi2000 wrote: All I have to say is, go ride the bike you already have sitting in the BARN arghhh, and you were worried about killing yourself on a motorcycle lol. little wheels and big holes= NO FUN, but seriously go ride that bike man.

Admit it, you really want my motorcycle don't you?

No just an advocate of riding, and think people should DOOOO eet.

Seriously add rake to the front...turn a little too hard at higher speed with one of these, and you will do a really awesome superman impression...and also a really awesome impression of Launchpad McQuack (google him if you dont know),

4cylndrfury wrote: Launchpad McQuack

OOOoooo a ducktales reference! (so my brother and i were into that series as children...)

Ducktales, wow that's an after-school flash from the past!