A 20" bike with engine. Has anyone done it?

Discussion in 'Performance Mods' started by 5-7HEAVEN, Jul 31, 2007.

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  1. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:Howziit guys. i have a DAHON folding bike with 35cc friction drive. i think this bike is meant for smooth pavement and short rides less than 15mph. let me hear your thoughts of using a stronger 20" bike, maybe a BMX. Thanks.


  2. bobo333

    bobo333 Guest

    i was thinking of putting my 50cc twostroke on a bmx but my engine is too tall and i would need to cut and move the top tube of the bike to make it fit, im not sure about your engine tho, it would be **** cool if you could!
  3. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:thanks for responding. i like the 20" bike size, but the DAHON can be squirrelly at times. just trying to find a stronger, better handling frame. i've seen 20" bikes with chinese engines on SPOOKYTOOTH'S website, so it can be done but not on BMX frames.
    Last edited by a moderator: Aug 4, 2007
  4. fogg4444

    fogg4444 Guest

    Ive Done It!

    I got the kit for $144.50 off ebay and put the whole thing together from scratch. I mean the bike started as individual pieces. I found a frame(not schwinn) with a fork and that was the beginning. I had to get a new custom sprocket on the back to keep the drive rate the same so I got a sprocket from the motorcycle/scooter shop, i think it was like 28 or something. I can go 35 and got 150 miles per gallon. But then at about 400 miles I blew a head gasket. Then I took it apart and made a new el cheapo head gasket. Thhen as I was putting it back together one of the sides of the piston skirts broke so I tried to put t back together anyways and then a piston ring broke. Then I got really ****ed and gave up and bought a new motor off dax for $168.00. Just the motor but at least I can get replacement parts if I need them. Now it needs to get put back together. I also got pulled over the first week for driving int the bike lane and not being 16 yet but he let me off on a warning and told me to pedal it. Good luck.

    Attached Files:

  5. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:Fogg, that's the exact frame i'm looking for! what make is it, and did you buy it new? can you measure dimensions for me, where your engine is mounted? i have rack mounted engines and chinese engines, so i can go either way.
    thanks for the info.

  6. JunkersBikes

    JunkersBikes Guest

    5-7HEAVEN: for the cheapest price, (if you're wanting actual Schwinn) is to look for Schwinn Stingray Frames from the LATE 70's to early 80's, Those Schwinn frame for 20 inch came out in 1963 and the early year frames are pretty Salty (especially Krate series)

    or an even cheaper route, look on ebay or heck even walmart for those purple Brat's bikes, there's a guy here on the forums that has put an engine on one,

    side-note don't even try to put an engine on a schwinn fast-back frame, wasted about 2 weeks on one when I tried it, but that's how I like it though, live and learn and have dirty hands in the process....

    good luck
  7. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:Thanls for responding,JunkersBikes. now i know what to look for.

    what do you mean by "salty"?
  8. I think he means expensive, probably hot items.
  9. This 20" with coaster brake was my first MotoredBike and it worked quite well. I put probably a few hundred miles on it with no problems. Then I just wanted something new and different so now this frame just sits in my shed.
  10. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:as TERMINATOR II would say..."That's a nice bike." lots of custom mod, but it wouldn't work for me because it sticks out like a pink elephant. i'm trying for low profile.:cool:
  11. JunkersBikes

    JunkersBikes Guest

    sorry about that, I mean those are pretty expensive items, or "hot" as Paris Hilton would say lol
  12. Edward

    Edward Guest

    I just got back from a ride on the Bratz Bike. I went up to Ottawa Ks to go on a ride with a guy who just bought a used china scooter from me and is new to the two wheeled world, but alas he flaked on me, so I went for a cruise around town. The bike is really too small for me and is girlie to the max but with the engine no one seems to notice. I'm a secure guy and not out kruisin for babes so it doesn't really bother me. Of all the engine installations I've done the Bratz was the most direct bolt on with the exception of the carb. A 45 degree adapter must be fashioned from a copper fitting and the end must be bulked up with either lead or epoxy and metal for the carb to fit. It is the only bike that I haven't modified for speed and is the only one currently running. hmmm. It will however wheelie from a stop or 5 mph roll.
  13. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:is that Bratz bike for kids aged 8+older? does it hold up with all the extra weight of 193lb adult and engine setup? is the bike frame strong enough?
  14. StreetPlanes

    StreetPlanes Guest

    I've got a Robin-Subaru Staton Inc kit on a 20 inch wheel. Here's what I learned:
    Most 20" bikes are too short to handle safely when motorized. Twitchy comes to mind.

    I'm currently extending and raking a 20 inch frame. In the meantime I put my 20 inch back wheel on a 26" frame and kept the 26" front wheel. If you try this use caution as the pedals on some frames will then be too low to the ground. Some brands of mountain bikes have higher pedals than other bikes. Also, you might get more ground clearance by using 20" cranks. Using a taller wheel on the front adds rake as if you cut and raked the frame a few degrees positive. A few extra degrees positive is a good thing but don't go too far.

    20" wheels are easier on spokes and less likely to warp provided you're not using cheap junk. You'll also need to consider regearing. 20" wheels ride slightly rougher than 26" wheels but I'm running high pressure tires so I can't tell much difference.
  15. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:yep, Streetplanes, my bike is definitely twitchy. i can't take my hands off the bars for a split second. even riding with one hand is tricky.
    i had a ROBIN friction kit on my folder. now it sports a Staton MISTUBISHI gear chain drive. much more power, but needs to be geared for better midrange.
  16. StreetPlanes

    StreetPlanes Guest

    Cheap fix

    Back in my younger days I used to ride custom Hogs, Triumphs, BSAs and Hondas. Replacing your 20" front forks with 26" front forks and a 26" wheel will get SOME of the twitch out and if you find the right fork it's bolt on. That said, it's not going to cure your problem altogether. The only way to really solve the problem is by stretching the frame and making sure the head rake is where it should be. And if you go too far with the rake then turning will become really hard to do in a safe manner.

    We used to build lots of choppers with standard Harley 16" wheels on the rear, Avalon 21" front wheels and 2 inch fork (tube) extensions. This made for a really stable straight line performer that could still turn and didn't require the cutting of frames. I'm building my motorized bicycles while remembering all the motorcycles I ruined while learning the hard way. Here's a blog page with photos of my daily driver: http://www.musecrafters.com/bloggingpoet/1259/Could+You+stand+200+Miles+Per+Gallon?.html

    You'll notice how the small wheel on the rear adds to the rake in the front. This bike is very stable and easy to ride even for us old dudes at 208 pounds.
  17. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool: since i need to fold the bike sometimes, i can't do any frame or wheel changes.

    Billy, i love your STREETPLANES ideas. stirs the creative juices in me. however, i'd probably want to build it so that the prop actually pulls my bike along. then i'd want the plane to fly 12" off the ground at times, for effect.:shock:

    Hmmm, now ya got me sidetracked from my twin engined project, and my pocket bike engine project, and my folding bike project.:confused:
  18. StreetPlanes

    StreetPlanes Guest

    I'm not ready to tell all as I know I've got competitors reading here too but I've got a few ideas for kits, adaptors, complete bikes and more that are going to send everyone in the business back to their drawing boards.

    As for going airborne I've not yet soloed and don't have my pilot's liscence.

    Now I'm off to my blogs to try and drive some traffic towards the forum.
  19. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:good luck in your business, Billy.

    i'd love to have a caged propellor pulling my SPITFIRE biplane SAFELY down the boulevard. maybe not flying 12" off the ground, but able to leapfrog on command.:shock: