Harbor Freight #97964 79.5cc 2.5HP - now what?

Discussion in '4-Stroke Engines' started by kallsop, Dec 26, 2009.

  1. kallsop

    kallsop Member

    I couldn't resist this engine for $89.99 (+ tax) which I think is a nationwide sale. 4 stroke, OHV, cast iron sleeve, ball bearing shaft, low oil shutoff, ball bearing output shaft, fuel shutoff, pull start, 79.5cc, 2.5HP @ 3600rpm, gas tank.The 20 page manual is here:

    Model 97964

    It's a lot of engine for the money.

    Now can someone recommend a rear mounting kit that will work with this motor? I have a MIG welder and can fabricate some steel parts if the kit isn't an exact match. I'm thinking to have a chain (or belt) and left side rear sprocket in addition to the bicycle pedal drive on the right. Of course a CVT would be nice but that doesn't appear to be an easy option yet.


  2. professor

    professor Active Member

    Kall, you have to gear it down with a jackshaft. I also picked up one of those HF engines last fall. Real nice engine. I don't know what set-up fits it. It is kind of heavy on the tail of a bike (it weighs 20 # on my scale), then you need a hd rack to hold it and reduce the gearing. I plan on putting one in the frame to get the wt. down lower.
    I think the guys from EZ motorbike have used the HF.
  3. give me vtec

    give me vtec Active Member

    I couldn't resist either... I just picked one up today. Now I will be looking for a new bike and a way to mount it.
  4. HF Greyhound engine

    Hi guys, I have not done one, BUT, check with RusticoRay, KilroyCD, or RDKryton, they have in-frame mounted these using a lot of HT type parts, and Q-Matic drives.

    Sucessful, and have been ridden by a variety of people.

  5. give me vtec

    give me vtec Active Member

    yeah... I was checkin out their work. They have done a lot of good ground work. Any news on how the engine rides??? This thing could be the next HT I think.

    I just stripped the tank air filter and exhaust off and must say that I am very happy with my purchase. I cant wait to ride it.
  6. kallsop

    kallsop Member

    There's definitely a business opportunity for these engines and a compatible bike kit that takes most of the guesswork away. It seems like a frame mount is tricky 'cause the engine is larger than the HT 2 stroke. With the higher weight of the engine versus the HT, a rack mount might be unwieldy. Maybe a high frame mount like the thatsdax "Titan 4 Stroke In Frame With Shifter kit" is the best.
  7. kallsop

    kallsop Member

    Can someone confirm the pocket bike FS529 CVT fits? That would enable a nice rack mount with the engine on the rack and not hung off the side.
  8. kallsop

    kallsop Member

    Good luck. I like the idea of a CVT, or maybe an internal geared 3 speed hub. My HT is a single speed and the next build will have gears, one way or another.


  9. they do make 2 speed freewheel coasters now but youd have to rig up a derailer
  10. KilroyCD

    KilroyCD Active Member

    Vtec, I really like the way the engine pulls. It has a good amount of grunt to it, and I need it 'cuz I'm no lightweight. It's also smooth, just they way a 4-stroke should be. Because it doesn't rev as high as some smaller engines, a smaller rear sprocket than the one we're using (54-tooth) could help gain some top end.
    By the way, I just found out today who makes that engine for Harbor Freight. It's a Lifan engine, which really makes that an excellent buy in my book.
  11. KilroyCD

    KilroyCD Active Member

    I don't know if it will fit, but the HF engine has a 5/8" shaft. If the CVT is for a 5/8" it might work. However, I doubt the engine will rev as high as the pocket bike engine that CVT is designed for, so the performance might not be as good.
  12. professor

    professor Active Member

    The only issue i have with the HF is it is wide.
    I spend some of the day stretching a frame 3 inches to make it fit up front and top. I think my feet will clear OK, if not I will heat and bend the crank arms a bit.
    I took off the muffler and tank like you guys did. That helped get it mounted higher.
  13. Tinker1980

    Tinker1980 Guest

    This is truly a great engine for MBs. I have one working as a friction drive, with a 2.75" roller. The engine hangs from the side like a big wart, but the only time you notice the balance problem is when pushing the bike by hand.

    I have noticed that, without the fuel tank and muffler, the engine fits nicely in the frame of my Sun Ez-1 recumbent, under the seat just in front of the back wheel. There would be NO pedal interference, low center of gravity, and with a 20" wheel, you wouldn't need to gear it down as much, although you'd still need a jackshaft.

  14. professor

    professor Active Member

    Mark, how about a pic or 2?
    What speed does it run?
  15. Danny3xd

    Danny3xd Member

    Go'in to pick one up in 30 mins!
  16. Tinker1980

    Tinker1980 Guest

    It will cruise easily at 30 MPH, slows to 20 or 25 on a decent hill, the fastest I've made it go on level ground is 30 MPH.

    It's really rather clumsy looking, and there is no clutch - if you are moving, the engine is turning. If it didn't work so well, I'd change some things around.

    I had to change the exhaust, the muffler that came with the engine kept the seat from going down - I was too short to ride it!

    I also have a short video:

    <object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/vvaclqPiOzo&hl=en_US&fs=1&"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/vvaclqPiOzo&hl=en_US&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>

    Attached Files:

  17. KilroyCD

    KilroyCD Active Member

    In addition to taking off the tank and muffler, we replaced the air cleaner with a Whizzer WC-1 unit. This also allowed it to clear the frame a bit better.

    Attached Files:

  18. kallsop

    kallsop Member

    The CVT would possibly need some adjustment for the 2.5HP rev range, but I'm moving towards that solution. Rack mount, CVT, left side sprocket. Simple is best, but not so simple that it doesn't work :)
  19. atombikes

    atombikes Member

    Got the last one from my local HF store. On sale for 89.99, plus I used the 20% off coupon, so OTD price was 71.99. And they gave me a free flashlight to boot!