Newbie from Albuquerque , NM. Altitude 5200ft!

Discussion in 'Introduce Yourself' started by pessen, Feb 17, 2009.

  1. pessen

    pessen New Member

    Hey Everyone,

    I just recently started looking into putting a motor on my DiamondBack mountain bike. I am a longtime recreational biker, but have recently started using my bike to commute to work a lot. This will be my first time converting a bike to be motorized.

    One question I had, (I'll search to see if I can find info before starting a new thread), that someone may be able to help out with is this: in doing research on the internet I found someone who mentioned that the 2 stroke engines (Such as the SkyHawk) were a little weak at high altitudes. Something to do with the jetting being set for sea level and not high altitudes. Does anyone have experience or knowledge of modifications that may have to be made in order to get optimal performance at high altitudes? Or any suggestions on engines that aren't affected by altitude as much?

    Anyway, I am excited to learn more and hopefully join the ranks of motorized bicyclers soon! Thanks in advance for any helpful tips!


  2. Skyliner70cc

    Skyliner70cc Active Member

    Use a 65cc engine. Use a SBP shifter kit to maximize the available power. Get a Dellorto carb (do a search) for better idle, low speed, and transition to high rpm. Stock carbs can be adjusted for high speed operation but have an overly rich idle and low to mid rpm mixture for our altitude. Ultimate goal would to purchase a tuned pipe from Andy Inchville? or SBP when they sell one.

    Do not use a 49cc engine, they are weak at our altitudes.

    PS Every engine is affected by altitude from piston, rotary, and turbine; its simple physics and some thermodynamics.
    Last edited: Feb 17, 2009
  3. pessen

    pessen New Member

    Thanks for the suggestions. In doing some looking online I realized that New Mexico's DMV requires registration and licensing on anything over 50cc. In addition to riding it around the city, I would also be riding it on a military base, so I might face additional scrutiny.

    That was why I was wondering if there was any way to modify a sub 50cc engine to work well at high altitudes.
  4. Skyliner70cc

    Skyliner70cc Active Member

    Get a shop to engrave 49cc on the engine side covers. There is no way to tell a 49cc from a 65cc anyway without disassembling the engine and taking measurements.