Harbor Freight 79cc 2.5HP 4-Stroke Engine Manual

Discussion in 'Spare Parts, Tools & Product Developement' started by loquin, Dec 9, 2009.

  1. loquin

    loquin Active Member

    Attached Files:

  2. loquin

    loquin Active Member

    Torque - Greyhound 2.5 HP 79cc Engine

    I submitted a request to HF's technical support group, asking for Torque curve information, and included a copy of one of Honda's Torque curve as an example.

    The reply is below:
  3. fuzzdobber

    fuzzdobber New Member

    Just remember....

    Hey Loquin! I spoke with you last week and can actually enjoy my time and talk without having to say " I can not advise on modifications " on my time off. I am exited to help you and possibly expand this hobby. As a start, check out www.arcracing.com ... there are wonderful upgrades for the Jiangdong Honda clones that you have inquired about. I would say the biggest problem of all that will be had is the low oil shut off...When the oil sloshes to one side of the crankcase rapidly (say a sharp turn) the engine will shut off. We constantly get calls on this. Bypass the sensor and keep the oil level checked. I can get wiring schematics and more, just not while I am being recorded. **Wink** This is definately a great idea and i would love to share my theories of a inertia generated bike, based on generated power of the human muscle. Gear ratios can power a battery kinda like a water wheel , with no effort with the right gearing you can go up hill with no effort and charge the loss downhill. Lets go green all the way, no exaust! All we need is a sproket, alternator, regulator, battery and the same brake system a gas system has. We could basically use a dimmer switch ( example ) for a throttle however a potentiometer would be prefered.
    To end this with my theory, if you have a bicycle with 2 wheels of course, one wheel driving by power derived from a source and the other wheel spinning at the same rpm charging @ the same amperage you are using. You have a free bicycle that rides on it's own (at no load) The only down fall I have found is the more weight on the bike the higher the loss of ampiers, therefor the charging wheel will not keep up with the load loss ultimately. For this I assume a third smaller wheel, to up the ratio, will need to be added speeding up the charging process. Sproket sizing is the miracle of this theory.

    Moral...Think simple stupid!

    Michael Rhembrandt
  4. ibdennyak

    ibdennyak Guest

    Hmmm, over square bore and stroke.......should handle revs pretty well :idea::devilish:
  5. professor

    professor Active Member

    Michael- glad to see you here!
    About the inertia bike you posted about- the losses are far too great to get some power the way you describe. You NEED a motor. I have a Greyhound and it is on a (work in progress) gas/e-bike hybred.
    Hang around for awhile, get some ideas and join in to the building phase.

  6. swbluto

    swbluto New Member

    So the power at 3000 RPM (314 radian/sec) and 4.0 N.m. is...

    314*4.0 N.M. = 1256 watts which is 1.68 horsepower. I don't know how much the peak horsepower improves at the 3800 RPM, but I think maybe 1.7-1.8 HP may be realistically pessimistic?
  7. fuzzdobber

    fuzzdobber New Member

    Yes, a motor will be a necessity. Ever notice we are going back in time? I remember an old moped with pedals that my father had in his junkyard. The only difference is gas vs. electric. The gearing will distribute the r.pm needed for a small generator to keep the battery charged. Depending on the size of the gearing as to how much power is produced. Heck with the right gear ratios there may be very little ampiers drawn from the battery unless going up hill.
  8. Cozmik Mezzenger

    Cozmik Mezzenger Active Member

    Here is the Predator 79cc user manual.

    Attached Files:

  9. Frankenstein

    Frankenstein Well-Known Member

    Does anybody have solid measurements on this engine without the tank installed?