79cc HF engine "deal" or hype ?

Discussion in 'General Questions' started by andyszyd, Jan 13, 2010.

  1. andyszyd

    andyszyd Member

    Reading all post about this engine I was about to get one, but then I cooled off.


    1. You can't beat the price (below $100 for 2.5HP engine).

    2. 2.5HP and good torque.


    1. Difficult frame mount fit on most bikes.

    2. Too heavy for rack mount.

    3. Not powerfull enough for a "pusher".

    4. Only about .4 or .5 HP more than Honda/Titan/HF52cc 2 stroke at 10-14lb more weight (80-120% more WEIGHT).

    2. Weight 22lb 10lb more than Titan, Honda 50 at .4 HP gain, 14lb more than HP 52cc 2 stroke at 2HP+? .4 gain at 14+weight.

    3. How it is a Honda 50 "killer" with only 0.4HP more (19%) and 10LB + (54% more) ???

    3. Can you really take adventage of its torque without a kind of
    shift kit or CVT?

    How do you propell the bike to get it to the "new speed record" using all 1speed (3rd gear only) most popular setups?

    I do not want to peddle heavy engine + bike + my weight to 10 MPH or more to reach "new speed record for $79.00 " sorry.


    I just can not justify to buy it only cause it is a "bargain" since I can not see an advantage to use it for MB in comparison to other engine options available.
    Last edited: Jan 13, 2010

  2. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    Hi Andyszyd,

    The biggest advantage to using the HF motor would be as a replacement for a blown 2 stroke motor because many of the kit parts can still be used [gas tank, throttle, rear sprocket, chain tensioner, etc]. The HF motor would only need a motor mount & drive system to make it workable.

    I agree with you about size, weight, and the slight difference in torque, and you are also 100% correct about the "Honda Killer status".

    We have tested the Q-Matic [dealers conducted the tests] with the HF motor and decided to produce our drive to "bolt-on" the motor if anyone wants to give it a try [must request the drive to fit the HF motor when ordering].

    We are able to set the Q-Matic clutch system and ratios to make it work with the HF motor.

    Have fun,
  3. stealthc9

    stealthc9 Member

    well, @ how many rpm's are the honda, and titan motors making that power?? The HF engine is makin the claimed power at it's Governed rpm. Disable the governor and you will have more power. Now I dont know how high these engines can rev. But I am willing to give it a shot...
  4. andyszyd

    andyszyd Member

    "Blown 2 stroke motor" ?

    I think you mean 2 stroke HT motors, not 2 stroke quality motors like Mitsu and Tanakas.

    They very rarely "blow" unless you feed them pure gasoline.

    In case of HT motors you've got it right.

    Still HF 79cc engine at 22lb + weight of one speed 3rd gear only kit + 45lb bike does not rock my boat.
  5. andyszyd

    andyszyd Member

    Nothing wrong with that, you can hopefully get safe 4800 RPM out of it, but you still need something better than 1 speed set up to take advantage of increased power band and torque of this engine and to offset its weight.
  6. stealthc9

    stealthc9 Member

    Well, I dont want a speed machine. Im putting it on my Schwinn OCC Stingray, So Im not concerned with the weight. Or the Speed, Like if I can get my bike to do 45mph i'll be happy. (then I can keep up with traffic)
    Last edited: Jan 13, 2010
  7. arceeguy

    arceeguy Active Member

    Don't look at just HP.

    The HFT 79cc has torque, and needs to be geared accordingly. Disable the governor, the low oil switch and keep it under 5K RPM's. I would estimate gearing maximum sustained cruising speed for around 4000 RPM's. In a little mini-bike, the 2.5 can cruise at 40, yet have decent acceleration due to its low end torque. (with no gears) Gear a 50cc two stroke to do 40 and you won't ave enough torque to pull a lollipop out of a baby's mouth. (in other words, get ready to pedal!)

    40 on a doodlebug minibike is even more scary than 40 on a bicycle. Talk about "squirrely" handling!
  8. stealthc9

    stealthc9 Member

    If I was doing direct drive what sprockets should I use? 11tooth front with how many rear?? on a 20" schwinn chopper with the 20"x4" tire I would like to cruise at 45mph
  9. Happy Valley

    Happy Valley Active Member

    Loses me right there, add the drive components and for me it's out of the realm of MAB and into another category.

    Nevertheless, it'll be interesting to see how reliable these engines will be over time and how they hold up with actual accumulated mileage. I well remember back a few years when the HT engines were becoming popular and the early enthusiasm for them.
    Last edited: Jan 13, 2010
  10. Youngbird

    Youngbird Member

    Not gonna happen, Stealth. You cant use a single gearing to do what you want to do. You need gearing or another drive setup. Look into MaxTorque convertors(drive and driven) then we'll talk some more. Or better yet....go toEZM and check out the Q-Matic Silent drive. Good luck.
  11. andyszyd

    andyszyd Member

    Do your math before you do your "built".
  12. stealthc9

    stealthc9 Member

    Ok well I dont have the funds to put out on that EZM kit. So Im gonna get a MaxTorque Clutch, there sprocket wheel calculator says if I run my 44t sprocket, MaxTorque 10t clutch,with my 21.5" outter Diameter Tire. my max speed would be 52.33mph@3600rpm's...But I doubt the HF engine would get me there. Im gonna try it anyways tho.
  13. arceeguy

    arceeguy Active Member

    Don't waste your time. The gearing is way too high. (numerically low)

    A rack mount friction drive would be a possibility. Mount the engine on the rack and drive the roller with a chain through a centrifugal clutch. A larger roller (maybe 1.5" +) or gearing up would make up for the lack of RPM's. (the two strokes scream over 6K)
  14. stealthc9

    stealthc9 Member

    excuse me? I was not rude to you in any way. I asked questions, comments that you may make, need not pertain to me.

    Do my math before you do you "built"...umm **** yourself. I build things, yes. I have built engines before. If you dont have something pertaining to my question, then dont answer me. You're the rudest member I have seen on this forum.
  15. KeyWest

    KeyWest Member

    Hello, this is going to be a good thread."deal" or hype ? well let me tell you guys somthing, I bought the 79cc engine and made a pusher with mine.This engine is great everything that I had hoped-for lots of power it will cruise nice 30 mph or slower but if you are in a hurry it will go over fourty.I did three mods that just make all the power of this engine work perfectly,get rid of the governor,striaght pipe,no restriction on the air cleaner.I think the greyhound is going to be hot in the motored bike community.I think that this engine is great.
    I also made a pusher out of the big brother H.F. engine 6.5 H.P. man if you want fun that engine will put a smile on my face every time I look at it. I did no mods to it and it is a pleasure to ride mostly long trips,check out my pictures of both rides in the push trailer section.
  16. professor

    professor Active Member

    Well, the engine is a deal for me. It makes good power at real low rpm. It is pretty quiet too. If gas bikes were legal here, the one I got would be driving the wheel thru a jackshaft rather than powering the onboard genset.
  17. stealthc9

    stealthc9 Member

    im just gonna get another happy time. I've only had a cdi fail on me...i'll get a 28 or 30 tooth sprocket so I can do 45 like i want
  18. arceeguy

    arceeguy Active Member

    They are a great value for the dollar, better get one while you still can though........
  19. stealthc9

    stealthc9 Member

    i have an auction won, with bgf (i am currently running a bgf now)...
  20. arceeguy

    arceeguy Active Member