Help on first build? I have plans and ideas, but can they work?

Discussion in 'Introduce Yourself' started by Money Mike, Nov 7, 2010.

  1. Money Mike

    Money Mike New Member

    Hello everyone! Like I said in my first post I'm new to motored bikes as well as forums in general. So, my bad if I F somethin' up. But let me know.

    My first build is going to be for my girlfriend and the second is going to be mine. We both lost our licenses and are moving to a state that allows us to ride these things so long as the engine is <50cc and "cannot exceed 30mph on a level surface". I feel I must get a 4-stroke engine, being as this will be our primary transportation and I don't want to deal with clogged injectors or trying to mix oil and gas at the pump etc...

    One of my biggest problems of course is full suspension vs hard tail. It will be my only transportation so I know a hard tail would seem better. But, knowing us our primary routes will probably include trails through the woods and such. For that I REALLY want to get a full suspension. I'm aware of most of the downfalls of a full suspension and can conquer most of them. My question about this is the chain tensioner. Will the chain fall off if going over a hard bump? Assume I'm riding and jumping small dirt dunes (I probably will be, I'm an ex BMXer). Will the chain pop off? Is there a high quality chain tensioner that I could buy or modify to be a close to full proof at possible? I've read through the threads about this but I only find small mention of the chain popping off sometimes. If the chain pops off a lot on the full suspension no matter what I do, unfortunately I'll have to go for hard tail.

    The bike. I'm going to get a mountain bike, probably from china mart, take it apart, put it back together (the right way) and on we go to the engine. I assume anything other than aluminum would work?

    I'm going to use a 49-50 cc engine. Frame mounted on hard tail, rack mount if full suspension. I can not use friction drive, it MUST work when wet. I'll probably use it as normal, but has anyone ever tried using the engine to turn the front sprocket on the right? Somehow allow the peddles to remain stationary while the sprocket they turn moves? I'm sure it can be done, though it may require a lot of custom fabrication. Not sure if it would work well though. That might be the third build :grin5:

    Lights... I bought some cheap o lights off eBay.

    3AAA powers the headlamp, so 4.5v and it says 5w.
    2AAA power the taillight 3v. the Watts = unknown
    Some $10 "lowest power consumption" turn signals / break light OTW too.
    I've learned a lot from you guys and I've decided to rewire them to a 12v 8Ah battery, designed for the e-bikes.

    Lights are nothing compared to the 12v 55w-ish things I want to power on each of the bikes. While many have problems powering just lights, this should be interesting.

    To recharge the battery, fun for everyone eh?. I plan to install a 12v 5w solar panel or 2. Maybe an e-bike motor as a generator as well. Perhaps one of those flip on side wall friction generators too? Connect them all to the battery charger and see what happens.


    I have a multi-meter for the electrical.
    I'm thinking about buying a welder from HF, that $100 one everyone talks about. I have sockets and wrenches and screwdrivers tire change stuff... all that normal stuff for "normal" bikes. Any other fairly important and not obvious tools I should have for a MB?

    Any help, questions, or comments, would be appriciated.
    Thanks in advance,


  2. wheelbender6

    wheelbender6 Well-Known Member

    Welcome to the forum. I'm not a regular off road motor bike rider but I'll give you my 2 cents worth. If you plan to use rear suspension, use a rack mount type of motor. It eliminates the chain problems.
  3. Money Mike

    Money Mike New Member


    I was definitely leaning towards the rack mount style engine because of that. The center seems like a better place for extra weight, especially while I'm in the air. But if I get a full suspension It'll probably be the rack mount. I cannot afford the chain falling loose.
    Last edited: Nov 7, 2010
  4. RedBaronX

    RedBaronX Member

    regarding aluminum (since I just had an aluminum frame crack after a "mere" 300 miles)

    If you are going with a budget bike (ANYTHING from Wal-Mart), stick with steel. If you are going for a name brand bike-- bike markers actually KNOWN for mountain bikes (Trek, Cannondale, Gary Fisher, etc), aluminum will be fine.

    As for 2-stroke vs 4 stroke-- if you are going with a rack-mount anyway, it's a case of you might as well go for the 4 stroke.

    For 12v solar panels-- I was looking at some myself and I didn't find any that were compact that looked like they would be effective (I think I was finding solar panels that were like 10" x 18", which is HUGE for the back of a bike). If you are finding something more manageable, I would be interested in them myself.
  5. Juwalantz

    Juwalantz New Member

    Jack shaft kit should turn your front sprocket so u can shift gears