40 MPH Club

I put a lot of research into this bike. It is my first motorized bicycle but I was in the bicycle industry for large portions of my life> I have built countless road and mountain bikes for racers and designed a few road from the ground up. Raced middleweight superbike on a GSXR 600 for 3 seasons. I put in a lot of hours with the dremel porting and many more tuning and setting everything up. I have about 3/4 of the first gallon mixed for break in thru the motor. Hit a steady 40 to 41 on a flat stretch today next to my friend on a Yamaha FZ1. I am loving the bike and excited to finish break in, mix a good gallon with 50 to 1 synthetic, get a good expansion chamber, carb, intake and maybe a 36 tooth for the rear and see what she will really do. Oh the bike is a relatively light 700c fixie style road bike.
 
Same as mine pretty much... the bike is a $79 pawn shop special and the engine is a Dax bottom with the top end from another engine, stock NT carb, Fred head, and a modified KTM pipe... still running the 44 tooth sprocket here too but was able to hit 41mph on a stretch of flat straight road. I did spend a good amount of time with getting the porting and squish clearance just right and the power comes on very smooth and linear, not peaky at all. My next move will be to add a 20mm Tillotson carb for better midrange and top end, and hopefully a few more mph before I switch to a higher geared rear sprocket so I can reduce my cruise rpm to under the 8k mark.
 
Not sure what carb i will end up ordering. I keep having delusions adout building one from scratch. I'm curious how the 20mm Tillotson works out as it would be way easier and work much better. The engineer in me just wants build what i have in my head. This bike is a test mule and I am having an absolute blast witg it. I keep trying to bring motorcycle buddies into the mix with me and they resist. The friend that rode his FZ1 with me yesterday was quite suprised and impressed though. I'm rambling, just can't get over howuch fun this is.
 
Yup.. I was supposed to get a few friends in on building these but they backed out after I ordered my first kit... we all ride motorcycles but have our toys too. One of my friends built a really neat Honda Ruckus and he was going to buy a kit but backed out after getting a layoff notice from work, so I was the only one here that built one. I also ordered a Fred head at the same time so this thing never even started up in stock trim... took it for a few rides then made a pipe for it, took it out for another ride then brought it home, took it apart, and started doing the porting work and other mods... I got a collection of carbs and reed valves over here so my next step is to put a bigger carb on this thing so it can breathe like it's supposed to. I'm thinking the Tilly will do what I want it to, but I've also got my eyes on a Mikuni or Dellorto.
I do agree tho... these things are a blast to ride around on and tinker with...
 
I spent 14 years riding and racing Suzuki GSXRs and I have had more fun in two months with this motorbike than in all those years on the superbikes combined. Heck i don't want to go into work right now. I just want to go ride.
 
LandSpeedRecord said:
I spent 14 years riding and racing Suzuki GSXRs and I have had more fun in two months with this motorbike than in all those years on the superbikes combined. Heck i don't want to go into work right now. I just want to go ride.
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That's what happens when this bug bites you....lol!

Many of us know just how you feel.dance1
 
I've had that urge to just keep riding a few times... ya know like when you're headed to the shop and gotta slow down and pull in but want to just keep going and come back later because the weather outside is perfect... Happens to me a lot when I used to ride the Sportster to work too.
 
LandSpeedRecord said:
I spent 14 years riding and racing Suzuki GSXRs and I have had more fun in two months with this motorbike than in all those years on the superbikes combined. Heck i don't want to go into work right now. I just want to go ride.
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I rode motorcycles, some fast and some just cool, for forty years.
Finally sold the last one last summer.
I could cruise a big kwacker at 120 with one hand on the bars, lying on the tank for miles and miles.
Going 40 on my silly bicycle (it only goes 27, BTW) just doesn't seem like a good idea. You know- crappy brakes, no shocks, skinny tires, spindly wheels...
I'm all happy at about 22, bumbling along smiling at the world.
Motorized bikes are really fun!
dance1
 
Slogger said:
I rode motorcycles, some fast and some just cool, for forty years.
Finally sold the last one last summer.
I could cruise a big kwacker at 120 with one hand on the bars, lying on the tank for miles and miles.
Going 40 on my silly bicycle (it only goes 27, BTW) just doesn't seem like a good idea. You know- crappy brakes, no shocks, skinny tires, spindly wheels...
I'm all happy at about 22, bumbling along smiling at the world.
Motorized bikes are really fun!
dance1
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Yes they're a lot of fun...

My motorcycles are enjoyable, my motorized bicycles are fun.
 
My job is lucky i dont ride to work or i would likely ride right past it now and then ha ha. I want to run at Bonneville but keep that fun also. A lot of bicycles do get sketchy at speed. My last high end road bike weighed about half what this bike did before the motor was bolted on and the wheels maybe a quarter. I got close to 50 downhill on that one a few times. The geometry is much more stable on this one and 40 has me paying attention but it is stable enough. The brakes are even close to strong enough but could use pads with more bite. I have the set up pretty dialed in where I brake and clutch at the same time with my left and throttle and brake with my right. I ran a left hand brake and clutch on my GSXR so I'm used to it.
 
Back in my early 20's I used to ride a Huffy Stalker mountainbike to work... no engine, just pedal power... but I was in a Lot better shape back then and could pedal that thing up to 32mph and on my 5 mile trip to work I could average about 20mph.

Here's where it got fun... and this is still the fastest I've been on a bicycle... there was this big hill between Lackland and Kelly Air Force base that tied the 2 bases together so I would go in thru Lackland and cut across then go down that hill to the other side. Every morning I would pedal my way to top speed (or at least try to be around 30mph) before I got to this hill, then I'd pdeal as hard and fast as I could in high gear while ducking down chin on the bars style. I remember if a car was in front of me I'd shoot past them like they were sitting still (the speed limit on base is 30 and most people follow the rules more on base) then I would coast it down to a more sane speed when I got to the bottom.
I did this for several weeks but started to wonder just how fast I was hitting going down that hill so I bought one of those little digital bike computers, installed it and calibrated it, then got my wife to drive beside me and tell me how fast I was going... I wanted to make sure this thing was reading as accurately as possible.
Monday comes along and it's time to ride to work, I get up, get the bie out, and head off to Lackland, can't wait to get to that hill but taking it easy so I don't burn up all my energy getting to the hill...
Hit the straight before the hill and start to accelerateuntil I saw 32 on the speedo.... Down we Go!!! I'm pedaling as hard and fast as I possibly can without my legs triping up on me, chin on the bars and I'm haulin'... look down to see how fast I'm going and can't read the numbers that close to my face... so I pop up and look down to see the speed quickly dropping 46,45,44,43,42,41,40... in about 3 seconds or less just from the wind braking... I tried it everytime i went down the hill until my orders were up and I had to go back to my real job that was too far to ride to. my guess is that I was somewhere around 49 or 50 since it always took me 2 or 3 seconds to focus in on that little speedometer at 7:00 am before there's rteally enough daylight to see it good, but by the time I got focused in on it I saw the same 46,45,44,43,42,41,40,etc so I'm not really sure how fast I was hitting.
I probably shoulda took a ride on the weekend during the daylight to try it just so I could see how fast I was going, I probably should have made a bracket to mount the speedo down on the fork tube or somewhere that was about 18 inches from my face so I could read it with my chin down to the bars... I coulda done this or that, but I didn't so who knows how fast I was really hitting...
I just remember what a rush it was and actually looked forward to my ride to work every morning.
And now I got an engine on a bike that's better and more stable, but still hadn't topped that speed...
 
LandSpeedRecord- I can see the dual clutch/brake levers working fine for a skilled rider.
I rode a new '77 XLCH at Bonneville once, just out onto the lake at a dry time, no event or anything. The road just ran out and there was a sign and you were out on the salt.
I opened it up (all stock, brandy new) and went as hard as it would hop for 10 miles or so.
Never did a turn at all, straight as a string. I stopped to walk around a bit and realized that without my track I'd never find that road again. ;-)
On the way back I twisted it up to about 90 and was cruising along and if it weren't for the wind you felt like you could step off and take a leak. I did some big mile long figure eights (at speed) and it was really relaxing and sort of metaphysical. I was groovin out there. I bet a lot of riders have done the same, it's such an awesome place to ride.
The mountains are so far away they don't seem to move, the sky was deep blue, no visual cues that you were bookin'.
A motor bike is going to seem mighty slow out there. It would make a perfect place to test and tune, though.
My own bicycle wouldn't be up to 50 mph use. Something would let fly! : )
 
That was a really fun read, Dave. The young don't know how much fun they're having until about 25 years later.
It's ironic that a big hill can out-race a gas engine. I gotta go to Pike's peak sometime with a sack of brake pads.
 
Great story Dave! We had this saying at my old shop refering to being young "just a little faster" ha ha reminded me of that. Slogger, I have had a few of those moments on motorcycles, maybe two that you think back and smile, for the rest of your life really. I know the salt flats are a LONG way across. They have a short coarse from what I am reading that they run old beetles on, it's a much shorter run up and the traps are much closer. Looking at the current 50 to 100cc records I wonder if they wouldn't let some of us run that. I have a target speed for testing and hopes of what it will translate too on the salt. I am hoping the next event in mid September will tell.
 
You know what, a Chinagirl Streamliner would be fun to think about. The little engines top-end would benefit alot with a slippery and narrow, light weight, low-slung fairing.

How long before somebody builds one of those?
I wonder how fast it could go. With a hundred pound rider, out on the flats..
 
Sounds like a good idea to me.
I'll get right on it...

MV_dustbin.JPG


$595 for the plastic.....
 
If you look up Battle Mountain it's an almost perfectly flat piece of road, despite the name. They hold the human powered speed trials there. The fastest are hitting right at 80mph and a good strong male sprinter puts out about 1/2 a horsepower as measured on similar dyno's that bikes are measured on. I'm not sure what you would get if you put a well built China Girls in one of those streamliners. Let's just say fast enough that passing tech would get really tough.
 
If you could get one of these engines into one of those streamliners then maybe gear it so it could get moving and just let it accelerate slowly up to top speed, if there's enough road and it's geared so it could do 80 at peak power it should be able to do it, wind resistance does get stronger as speed increases but it quadruples instead of doubling when mph doubles.

the bike would also have to be pedaled or pushed up to 30mph or so if geared this high before it could accelerate on it's own.

The other factor in this is that human power has been measured around the 1/2hp mark, but at the rpm we can pedal, the torque is way higher so gearing for human power the big sprocket is on the cranks and the small sporcket is on the wheel and it's backward from engine power where we can have much more horsepower but a lot less torque. I'm guesing a china Doll makes about 2 1/2 to 3 lb/ft torque at best so we need that rpm and gearing to get speed, we also need it to be either geared in a way that it can accelerate on it's own but lack a little top speed or have a 2 or 3 speed transmission because if it's geared too high and the engine's max power rpm is too high, it may not be able to overcome the wind resistance to make it to the powerband which would also make it a lot alower than it could be... This is easily noticed in some cars and motorcycles that can actually go faster in 4th than 5th, or faster in 5th than 6th, and it's really noticeable in a truck that has poor aerodynamics.

I do beleive that we could get a very streamlined bicycle or trike up to 80 or 90 mph, or maybe even faster, but it'll need multiple gears or some type of push assistance to get it into it's powerband, then from there it's all about tweaking the top gear ratio to get the max speed.

Anyone else in here remember these little car/motorcycles from the early 80's? https://www.youtube.com/watch?v=BEsmqK4ijgs I think if we built something similar but smaller, lighter, and with improved aerodynamics, maybe over a tadpole recumabnt frame it could hit some impressive speeds...
 
the bike would also have to be pedaled or pushed up to 30mph or so if geared this high before it could accelerate on it's own.

I'm thinking small jato bottle here..
haha

Couldn't you use the bikes gears and derailleur to pull from a stop, then shift on up?

Make a lightweight, lay-down frame, little 16" wheels, lot of rake and trail for stability, clip on bars and a custom full fairing that covers everythang.
Out on the salt you don't need shocks or springs, a big gas tank or any brakes at all. Just two wheels, and a plastic bubble over everything.
No pedals. I bet it could hit 80.
 
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