Results 1 to 44 of 44
  1. #1
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    23

    250cc Rugged Mountain Bike Build (street legal)

    Hello everyone,

    I wanted to start this post because I planned on starting this awesome project where I'm going to build a 250cc, 4-stroke, street legal mountain bike. I already have a mongoose, which would have been most of the cost, that will be used as the frame.

    I'm currently in the registration and certification process, which I will pass for sure , but will be able to simultaneously work on the bike itself.

    I not building from scratch as most of the parts will be assembled: frame, engine + transmission, etc. It mostly going to be bolting, welding, and positioning on my part; bolting on intake and exhaust, hooking up radiator if water cooled, fuel lines and brake lines, the easy stuff.

    The whole purpose is to build the ultimate street and off-road mountain bike/motorcycle anyone has ever seen. This is a daring, but completely obtainable, project that will be documented and broadcasted on youtube, facebook, ustream, and my personal website for all the enthusiasts out there to see.

    From start to finish, frame to cold start, viewers would watch as a seemingly limited mountain bike is transformed into a rugged, off-road capable, street legal, 250cc, 4-stroke, super/ultra octane fueled, dual-suspension, tactical, all-purpose bike!

    I know there are a lot of the kilowatt electric bikes out there that even corporations are starting to pick up on via grants, some of which I heard can it 115mph?!

    I wanted to do this because it will be very fuel-efficient since the engine will be single cylinder and 4-stroke. It will have a multi-gear transmission so that it can go faster and still be efficient.

    I also think this project will do very well because people don't always get to see in-depth videos of some of the awesome projects people take part in. Not everyone gets to see how a car is built from start to finish, has a server is set up, how the "K" supercomputer was built, etc. So, that's why I plan to document.

    What thoughts and suggestions would you all have about this project and being able to see it from frame to cold start?

    Now that I think about it, I might buy a Mongoose Status frame.

    Thanks,

  2. #2
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    23
    Here's a picture of the bike and an engine similar to what I want to use.
    Attached Thumbnails Attached Thumbnails 250cc Rugged Mountain Bike Build (street legal)-file0003.jpg  

    250cc Rugged Mountain Bike Build (street legal)-file0007.jpg  


  3. #3
    mtbr member
    Reputation: cerebroside's Avatar
    Join Date
    Jun 2011
    Posts
    925
    I would not trust that bike under human power, let alone with a 250cc.

    Edit: To make this a bit more constructive; if you want to do something like this you would be far better starting from scratch as far as the frame is concerned. Post in the frame building section of the forum. Also, don't underestimate how much power a 250cc can put out, start with something smaller like a 50cc or electric.

  4. #4
    What could go wrong ...
    Reputation: Zoke2's Avatar
    Join Date
    Nov 2007
    Posts
    1,996
    that frame can barely handle pedal power so be sure and post a video of the first time you fire it up and the frame explodes ... I really want to see that
    I used to ride to Win ... Now I ride to Grin

    While my guitar gently weeps, my bike sits there mocking me

  5. #5
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    23
    Quote Originally Posted by Zoke2 View Post
    that frame can barely handle pedal power so be sure and post a video of the first time you fire it up and the frame explodes ... I really want to see that
    Quote Originally Posted by cerebroside View Post
    I would not trust that bike under human power, let alone with a 250cc.

    Edit: To make this a bit more constructive; if you want to do something like this you would be far better starting from scratch as far as the frame is concerned. Post in the frame building section of the forum. Also, don't underestimate how much power a 250cc can put out, start with something smaller like a 50cc or electric.
    Believe me, I'm planning this whole project out from exact length of tubing, mount points, chain guards, etc. I'm not some excited average Joe who wants to do something crazy without researching first.

    What I provided in my first post was just to touch base.

    I know about the frame and that's why I planned on reinforcing with with a few steel square tubes and using mostly welds instead of bolts and clamps like most gas/motorized bicycle kits out there.

    But, if you all really advise trying another frame or simply starting from scratch with the frame, I'm all ears!

    cerebroside: I have first hand experience with a 250cc on both a dirt bike and quad/4-wheeler. The reason I chose a 250 instead of a 150 or 100 is because I need the torque for multiple gears.

  6. #6
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    23
    Quote Originally Posted by Liu Kang View Post
    You want to put a 250cc 4 stroke engine on a cheap Wal Mart bicycle?

    Are you trying to troll or something?
    The bike in the picture was the initial bike I though about using. But as you can see in my first post near the end I stated that I would most likely change frames.

    Also I just posted about how I would reinforce the frame I chose with steel square tubes.

  7. #7
    I work in .001 tolerances
    Reputation: HomegrownMN's Avatar
    Join Date
    Nov 2004
    Posts
    1,243
    A couple of boys I went to school with built this for their grad project.
    Done right and done well
    Project M85 - Ultralight Freeride MotorCycle

  8. #8
    What could go wrong ...
    Reputation: Zoke2's Avatar
    Join Date
    Nov 2007
    Posts
    1,996
    Quote Originally Posted by macb6497 View Post
    Also I just posted about how I would reinforce the frame I chose with steel square tubes.
    exactly how do you plan to use steel tubes with an aluminum frame ... why not build a steel frame to begin with ... something like this
    Attached Thumbnails Attached Thumbnails 250cc Rugged Mountain Bike Build (street legal)-really-big-wheels.jpg  

    I used to ride to Win ... Now I ride to Grin

    While my guitar gently weeps, my bike sits there mocking me

  9. #9
    mtbr member
    Reputation: cerebroside's Avatar
    Join Date
    Jun 2011
    Posts
    925
    Quote Originally Posted by macb6497 View Post
    ...

    But, if you all really advise trying another frame or simply starting from scratch with the frame, I'm all ears!
    The way a motorbike engine of that size mounts to the frame is going to be seriously incompatible with any pushbike frame without pretty much rebuilding it.

    If you really want to do this, have a look at some motorbike frames and CAD up something, then think about how you are going to accomplish building it. Do you have experience/equipment for MIG/TIG or oxy? I hear that silver brazing is the best for starting out, but people in the frame building forum would know more (so ask there).

  10. #10
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    23
    Quote Originally Posted by Liu Kang View Post

    You're going to have to spend a lot of money on very good bike components to POSSIBLY make your project work.

    I stated I would take advise on whether or not to use a custom frame.

    If I build the frame from scratch then that solves most of the problems.

    I thought about using an already made frame for simplicity.

  11. #11
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    23
    Quote Originally Posted by cerebroside View Post
    The way a motorbike engine of that size mounts to the frame is going to be seriously incompatible with any pushbike frame without pretty much rebuilding it.
    I see then that I must make the frame myself.

    Aluminum would be sufficient as a frame but if the manufacturer doesn't make the frame strong enough then too bad, i'll have to do it myself.

  12. #12
    mtbr member
    Reputation:
    Join Date
    Oct 2010
    Posts
    641
    steel can't be welded to aluminum.
    the engine pictured, which is from what looks to be a 4x4 quad is WAY to big, and Way overkill for what you are wanting to accomplish.
    the honda crf 250r (water cooled) or crf 230f (air cooled) would be best options for the engines.
    most mountain bike trails are not open to motorized powered vehicles so why not just buy an older street plated dirtbike? thats what i did, i paid 1700 for a street legal 1996 honda xr600r, and love it for around town and out on the trails. i also have a crf250r for the track, and i have my mountain bike. not a single bone in my body wants to blend the 2 bikes, they are totally different.
    what state do you live in? how do you know you will "for sure" get it registered street legal?
    Juice

  13. #13
    mtbr member
    Reputation:
    Join Date
    Oct 2010
    Posts
    641
    Juice

  14. #14
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    23
    Quote Originally Posted by Der Juicen View Post
    steel can't be welded to aluminum.
    the engine pictured, which is from what looks to be a 4x4 quad is WAY to big, and Way overkill for what you are wanting to accomplish.
    the honda crf 250r (water cooled) or crf 230f (air cooled) would be best options for the engines.
    most mountain bike trails are not open to motorized powered vehicles so why not just buy an older street plated dirtbike? thats what i did, i paid 1700 for a street legal 1996 honda xr600r, and love it for around town and out on the trails. i also have a crf250r for the track, and i have my mountain bike. not a single bone in my body wants to blend the 2 bikes, they are totally different.
    what state do you live in? how do you know you will "for sure" get it registered street legal?
    A bi-metallic strip would have been used.

    The engine in the picture was just an example as it was attached to my 4-wheeler.

    Also, you're right on spot as to what engine I wanted to use and why. The crf is a great bike with lots of power.

    I also did a quick search and found these:

    Street Legal Requirements at DMV.org: The DMV Made Simple

    http://www.wsp.wa.gov/traveler/docs/...motorcycle.pdf

    But like you said, I can never be 100% sure I'll get approved.

  15. #15
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    23
    Yeah, this is where I got the notion that an electric bike could go 115mph in my first post

    "Electric motorcycles can hit speeds of 150mph,"

  16. #16
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    23
    Quote Originally Posted by Liu Kang View Post
    So it looks like the OP wants to build a motorcycle instead of a bicycle. You're in the wrong forum friend.

    Thumpertalk.com is just down the road. Bye bye.
    I've been on thumpertalk to talk about my android ATV trail locator app, but it isn't as lively...

  17. #17
    mtbr member
    Reputation:
    Join Date
    Oct 2010
    Posts
    641
    if this is something you REALLY NEED TO DO FOR THE HELL OF IT, get your legal paperwork figured out with the state first. then pick the components you are going to use, then start from scratch with cad drawings to build from. and build either an all aluminum frame, or use all chromoly.
    do it right the first time and dont kill yourself.
    Juice

  18. #18
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    23
    Not to seem arrogant, but this project really isn't difficult.

    If you step back and look at what I would need, excluding costs, it wouldn't seem unreachable.

    There are 2500 hp cars using aluminum and carbon fiber

    For the frame, what would really be needed?: Square tubes of different lengths from discountsteel.com, for starters, TIG welder or acetylene torch with RG-45 steel rod, a couple drill bits, grinder, band saw. And that would be it for the most part.

  19. #19
    mtbr member
    Reputation:
    Join Date
    Oct 2010
    Posts
    641
    i know its more involved than you make it seem for it to be safe.
    if you really know what you are doing you wouldnt have posted such a shitty bike as a frame example to start with, and you would have found a picture of what you really plan to use for the motor, not just go take a picture of one twice the size just because it was in your garage.
    Juice

  20. #20
    mtbr member
    Reputation: Rubicon73's Avatar
    Join Date
    Feb 2009
    Posts
    78
    I love it... Just make sure you video the maiden voyage for us...
    I ride faster than I should...

  21. #21
    mtbr member
    Reputation:
    Join Date
    Aug 2008
    Posts
    4,686
    I once joined a Corvette forum to talk about Mustangs, I got banned.
    I also joined a pro gun forum to talk about banning guns, I was banned too.
    Then I joined a mountain bike forum to talk about building a dirtbike.......

  22. #22
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    23
    Quote Originally Posted by Der Juicen View Post
    i know its more involved than you make it seem for it to be safe.
    if you really know what you are doing you wouldnt have posted such a shitty bike as a frame example to start with, and you would have found a picture of what you really plan to use for the motor, not just go take a picture of one twice the size just because it was in your garage.
    Just because I don't dedicate my life to worrying about how other companies produce their product doesn't mean I don't know what I'm taking about.

    I don't care how they make their bikes because I know how strong aluminum can be.

    You may be forced to follow standards because you really don't understand how things work, but I don't.

    People like me who understand things on a more in-depth level don't need to know some useless 5-point delta config because I understand the forces involved with machinery being I can calculate it when I need to, not open a text book to see how others have done it.

    I can reinforce the frame in whatever way I need. YOU may have to abide by manufacturer specs, but because I understand I can manipulate things to my needs.

    There are many ways to reinforce a frame, you just don't have experience.

  23. #23
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    23
    Quote Originally Posted by the-one1 View Post
    I once joined a Corvette forum to talk about Mustangs, I got banned.
    I also joined a pro gun forum to talk about banning guns, I was banned too.
    Then I joined a mountain bike forum to talk about building a dirtbike.......
    Well, that sucks. But, you're off topic.

  24. #24
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    23
    I'll build it and worry about forces on my own time seeing that most of you all are chained to standards.

    Here's a tip for the ones who deny: get an understand and stop following and listening to others.

    This project would seem simple to you, if you understood.

    I can see that most are stuck up; that's why you can never say you're trying to be nice.

    I guess being arrogant is necessary.

  25. #25
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    23
    Quote Originally Posted by Liu Kang View Post
    Look who's talking.

    You obviously have NO experience if you were thinking of welding steel to aluminum. If you knew anything of what you were talking about you would know that steel can not be properly welded to aluminum.

    Look through my previous posts for "bi-metallic". You'll understand. And don't even respond with "you need thicker gauge". Ever heard of do-it-yourself?


    Like I said in my previous post, I'll do it myself. Most of you are chained to standards and are unable to work around things.

  26. #26
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    23
    Quote Originally Posted by Rubicon73 View Post
    I love it... Just make sure you video the maiden voyage for us...
    I have plenty of videos on my website even the Executive Office Building picked up on. You can check out my meeting with them there.

    Do you still think that things cannot be done if you don't follow standards?

    Like I said in my previous post, I'll do it myself. Most of you are chained to standards and are unable to work around things.

  27. #27
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    23
    Quote Originally Posted by Liu Kang View Post
    You don't even know what you're talking about.

    Is "reinforce" a dead word?

    Are you certified in having done every possible structural configuration in the field of engineering?

    Like I said in my previous post, I'll do it myself. Most of you are chained to standards and are unable to work around things.

  28. #28
    mtbr member
    Reputation:
    Join Date
    Nov 2006
    Posts
    199
    Good for you for giving this a go. Don't listen to all the naysayers, you have a goal, see it through.

  29. #29
    mtbr member
    Reputation:
    Join Date
    Aug 2008
    Posts
    4,686
    Quote Originally Posted by macb6497 View Post
    Well, that sucks. But, you're off topic.
    Yes I am, and you're off-forum

  30. #30
    Wrench
    Reputation: FNFAL's Avatar
    Join Date
    Feb 2009
    Posts
    769
    Don't feed the troll.

  31. #31
    mtbr member
    Reputation:
    Join Date
    Oct 2010
    Posts
    641
    bi metallic material is used for specific applications where it is absolutely required. this really is not one of those cases. steel and aluminum can actually be welded together using explosion welding, or friction welding, but that is not exactly feasible or necessary for a diy project such as this..
    ive built parts for satellites, ive built offroad cars, ive worked on and fixed projects that started out just like yours is shaping up to be. there are standards used for a reason, they are typically the strongest, safest way to accomplish things. whatever you think you may know you are not displaying that knowledge in a convincing matter at all. IMHO you have approached this project the wrong way, and definitely didnt think things completely through before posting to a forum.

    will this bike also pedal with having such a big motor? what type of rear hub do plan to use?

    if it doesnt pedal this is absolutely off topic/forum.
    Last edited by Der Juicen; 07-29-2012 at 03:20 PM.
    Juice

  32. #32
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    23
    For the rest of the comments simply look through my posts and the answer will be there.

    In order from my most recent post:

    1.)thanks,
    2.)I said that?
    3.)Not at first
    4.)Define
    5.)You "think".

    Like I said in my previous post, I'll do it myself. Most of you are chained to standards and are unable to work around things.

  33. #33
    Suckin wind like a boss
    Reputation: big terry's Avatar
    Join Date
    Apr 2012
    Posts
    1,680


    epic troll is epic.
    If you arent bleeding, you arent riding hard enough.
    http://about.me/bigterry

    Quote Originally Posted by Hutch3637 View Post
    I don't need sex. My life fvcks me daily.

  34. #34
    mtbr member
    Reputation: mint355's Avatar
    Join Date
    Mar 2012
    Posts
    202
    Is it school holidays already???

  35. #35
    "El Whatever"
    Reputation: Warp's Avatar
    Join Date
    May 2004
    Posts
    18,831
    While you're not breaking new ground anywhere, I admire your creativity.

    These guys got ahead of you...




    IMG_1083 | CapitalDealsOnline.com


    Don't let the naysayers tell you it can't be done. But don't half-arse your efforts either...

    A few suggestions...

    - Make it a 29+... on get Surly to make you a set of Big Fat Larry tyres... yup, that'd be a 29'er with 4.5" tyres. Sweet.
    - Use a Suzuki Hayabusa engine.



    - K&N Air intake filter with Ram Air intakes
    - Use Gatorbrake's dual discs up front.



    - Avalanche MTN-10 Fork...



    You may be spending some money on the components, so your idea of starting with the Walmart bike is good. Weld aluminum lugs and bolt the steel reinforcements. Ducati's use the engine as a structural member, so it can be done. I can't see your weight bending the mounting tabs of the Hayabusa engine, so no worries there.


    You're welcome.
    Check my Site

  36. #36
    mtbr member
    Reputation:
    Join Date
    Apr 2010
    Posts
    1,663
    Exactly what "standard" are you blathering on about? The only "standards" I've seen people mentioning in here are the laws of physics. I'm a degreed ME who has built and welded plenty of things for a living and for fun. If you think a bicycle frame is the right starting point for this project, then you had better set aside some time to start "worrying about forces".

    After that, you can start "worrying about weight". You're going to need the burliest of DH forks/shocks to handle the weight of your bike after you add an engine and your "frame reinforcements". Same for the wheels. And brakes. By the time you're done, you'll have a bike that costs 2-5x that of an off the shelf thumper and performs worse.

    Motocross/enduro bikes have gone through decades of intense refinement and competition. What about them is it that you think you're going to improve upon in your garage/basement? Do you think Honda's hydroformed aluminum frame can be improved upon using parts from an aluminum bike frame, steel tube and "bimetallic" welding?

  37. #37
    AZ
    AZ is offline
    banned
    Reputation: AZ's Avatar
    Join Date
    Apr 2009
    Posts
    19,201
    2nd the 29er w/ Busa H.P. If you're going to go, go big. Want to see pics of the beast, with extra awesome sauce please.

  38. #38
    rebmem rbtm
    Reputation: juancho142's Avatar
    Join Date
    Feb 2010
    Posts
    416
    Come on guys, this dude is surely kidding and you are all falling for it. He´s probably at home now laughing in front of the computer and does NOT plan to put a 150cc engine on a walmart bike.

  39. #39
    rebmem rbtm
    Reputation: juancho142's Avatar
    Join Date
    Feb 2010
    Posts
    416
    I don´t always build bikes

    But when I do, I have the stupidest ideas ever.

  40. #40
    Single(Pivot)and Happy
    Reputation: Boulder Pilot's Avatar
    Join Date
    Jan 2004
    Posts
    1,461
    The OP seems have have everything sorted out in his head. May I respectfully suggest to the OP that you not proclaim your project to be a motorized mountain bike.

    I don't know where the OP is located but I, along with the majority of mountain bikers, live in areas where trail access is a privilege and many of us real mountain bikers understand that there are groups with money and influence that do not want mountain bikers on trails.

    As a trail advocate, I am constantly engaged in keeping existing trail access open for all mountain bikers and constantly advocating for more trail access. In California, property owned by Cal. Dept. of Fish & Game are off limits to mountain bikers (there are a few exclusions) because bicycles are categorized as motorized transportation.

    Shared use trails are trails that hikers, equestrians and mountain bikers are allowed to use. ALL definitions of shared use or multi use trails explicitly state "Non Motorized".

    If anti-mountain biking groups can point to an example of a "motorized mountain bike", there is a very real possibility that trail access for REAL mountain bikers will be jeopardized.

    I'm not saying do not follow your dream. I am respectfully requesting that the OP along with all others that feel the need to install any type of power producing engine or motor onto a two-wheeled frame understand the big picture and at the very least do not refer to their projects as a form of "motorized mountain bike".

    Respectfully,

    Jason L. Showalter
    Board Member, San Diego Mountain Biking Association
    The suspension of your bike sucks if it's different than mine. Really. It sucks. Big time.

  41. #41
    banned
    Reputation:
    Join Date
    Jun 2007
    Posts
    2,320
    Yet another - "Here's my idea, whaddya think thread.
    Give me input, know more than any expert, insult all with opposing views, now I'm butthurt so g-bye, and faack u'all 2".
    macb6497, Good luck, and at the next family reunion tell yur cuz Jeep Boy hello.

  42. #42
    mtbr member
    Reputation: pleepleus's Avatar
    Join Date
    Apr 2011
    Posts
    389
    Your going to want to start with a JEEP bike. They make the best 250cc mountain bikes. Make sure the front wheel has skoors. The wheel will fall off without skoors. Most importantly don't forget to get a map of the whole forest.

  43. #43
    mtbr member
    Reputation:
    Join Date
    Apr 2010
    Posts
    793
    Try advrider.com. Look in thumpers. Lots of builds. But remember, pedal bikes and motor bikes are two totally different beasts. I've built mountain bikes and toyed with building a dirt bike; but there really isn't a middle ground between them. (even a really really light dirtbike is still a dirtbike)

    Or just do as I am going to and buy a ktm freeride 350 when it makes it to the US.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •