?Recommendations for HF 90cc Engine Kit

Discussion in 'Motorized Bicycle General Discussion' started by Nehmo, Sep 10, 2012.

  1. Nehmo

    Nehmo Member

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    I want to use this HF 90cc engine . What are the recommendations for drive kits?
    I like the engine because it's cheap 4-stroke, and I'm settled on 4-stroke.
    I would suppose a friction drive (FD) would be the easiest, but I'm open to other arrangements.
    [​IMG]
    I believe this 99 cc and the 80 cc versions differ only in bore, and I may use either. I haven't bought either yet.
    I'd like a specific recommendation of a kit that's already been used to mount this engine.
     
  2. ocho ninja

    ocho ninja New Member

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    I posted a similar discussion topic/ question a while back.... They don't come in kits,it's more of DIY build.

    Just search for similar builds in the search bar and you will find other things people are using to make a list of what you will need for your build


    As far as mounting hardware, some used the kit mounting plates sold with hs 49cc four stroke kits.... adapted for the 99cc to fit

    Others custom fabricate their own
     
    #2 ocho ninja, Sep 10, 2012
    Last edited: Sep 10, 2012
  3. Nehmo

    Nehmo Member

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    You would think, considering the wide availability of the engine, someone would have pre-packaged the parts needed to connect one to the wheel of a bike.
    But Okay, I'll design one from scratch. How hard can it be?
    I'll go with a friction drive because the existing wheel can remain the same.
    Beyond that, I'll have to do some reading. Any suggestions are welcome.
     
  4. wayne z

    wayne z New Member

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    Here's what I did.
    http://motorbicycling.com/showthread.php?t=30738
     
  5. ocho ninja

    ocho ninja New Member

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    I think the main reason their not available in widely accible kits is because of legality issues... Look up the laws in your area and see what they have to say about motorized bicycles
     
  6. wayne z

    wayne z New Member

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    Well, Most of the Chinagirl engines are 66cc so they are illegal in most states too, but there's plenty of them around because of the small investment to purchase one.

    The HF engines only recently became popular to motorbike builders, and the domestic tranny builders just haven't caught up. The weak economy is also having an effect. Not as many people willing to spend the money it would cost for a reliable HF enfine/ tranny kit deters innovators from tying up money and risk to produce them.
     
  7. The_Aleman

    The_Aleman New Member

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    It's really difficult to put together a kit that will work for everyone, too. There's way too many different bicycle frames out there.
     
  8. bigbutterbean

    bigbutterbean New Member

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    the ezm qmatic transmission will bolt on to the 79cc and the 99cc. you may have to grind your shaft down a teeny bit depending on the shaft size I think. for the 99cc, there is also a transmission available at www.affordablegokarts.com that is designed specifically for the 99cc. I suppose it would also fit the 79cc. the agk tranny is much cheaper than the qmatic, but you have to buy a clutch separate. there are no complete kits available for the 99cc, so you will have to hook up your own throttle linkage and exhaust and also find a motor mount. the 4 stroke kit mounts will work but may require some modification. you will also need to remove or disconnect the governor. most here just disconnect it. ezm, the company that sells the qmatic transmission, sells flex pipe exhaust for like 36 bucks, or you can make your own. but you certainly do not have to build a transmission completely from scratch. check the diy section for more ideas and info.
     
  9. Nehmo

    Nehmo Member

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    The clutch you refereed to is this? [​IMG] That's a good start. I suppose I should just start buying stuff.
    [BTW, I don't have a home internet connection, so I have to WiFi it in a public place and read later. I can't respond quickly is what I'm saying.] I'm going to copy that whole site. (I use WinHTTrack for that.)
    I'm convinced to go through with the project. It doesn't look like it's going to be prohibitively expensive.
    OK let's start with a list of materials:
    • Engine
    • Clutch (as just described)
    • #35 chain
    • What are you suggesting for a transmission? It would seem this chain coming off the sprocket on the clutch would go directly to a sprocket fixed to a friction drive roller.
    I really need to read-up some. And I need to read the In frame Predator fricton drive build.
    Who sells the EZM "Q"-matic? Maybe Quenton Guenther's
    EZ site is being re-worked. I did find piratecycles1.com Their kit:
    • Kit includes:
    • Made in the USA EZ Silent Drive System
    • Complete Engine with pulley and shims attached
    • Motormount and bolts
    • Chain Guard
    • Parts Bag(rubber rings,bolts, tank straps, petcock, fuel line and misc
    • Throttle and matching grip
    • Tank (Black)
    • Sprocket (hardware in bag)
    • Ball bearing chain idler
    • 9 tooth #41 Sprocket
    • 5" Pulley
    • 8 6x1x16mm 8.8 bolts
    • 8 6mm lock washers
    • #41 Chain
    • #41 Master Link
    • Clutch Lever and clutch adjuster

    One question at this point: It seems the popular position of the engine is in-frame. What about above the rear wheel? Why is in-frame considered preferable?
     
  10. The_Aleman

    The_Aleman New Member

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    You don't need to buy the clutch unless you buy AGK's "jackshaft" transmission, too. The Q-matic comes with a clutch.

    In-frame is preferable for 3 reasons: looks, bike balance, and looks.
     
  11. Nehmo

    Nehmo Member

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    But (except on the other sex) I don't care about "looks". I'll use charm instead.

    Of the two mentioned AGK's and Q-matic, what are the relative merits? And if I were to buy a Q-matic, is his site really down? It sure seems like he's a meticulous builder. Where do you buy Q's stuff?
     
  12. The_Aleman

    The_Aleman New Member

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    You have to contact a dealer. I don't know where you are, so can't help you with that.

    AGK's gearbox is wider, and less expensive, but offers better performance. Easier to service and customize. It's also less of an eyesore, some would say.

    The Q-matic is slightly narrower and more expensive, but is smoother. Some would say it's uglier, too, on account of it's huge gearbox cover.
     
  13. Nehmo

    Nehmo Member

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    I'm in Kansas City, Kansas now, but I'm not adverse to doing business over distances. The stuff will probably need to be shipped anyway.
    The Q-matic is available only through authorized dealers? Is that what you are saying?
    The AGK products seem to be available directly from their site. I already called: got voice mail.
    OK, the Jackshaft Assembly. "Jackshaft has a 22t input sprocket and a 9t output sprocket". How can there be a gear reduction when the input sprocket has more t then the output? Maybe the terms "input" and "output" are used differently than I'm accustomed. The pic seems to show a 9t drive and 22t driven.
    The in-frame FD mentioned above looked OK. I'll need to read some more.
     
  14. The_Aleman

    The_Aleman New Member

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    The clutch has an 11T, then -> 22T (2:1). So with say, a 56T sprocket and 26" wheel, you get a 12.44:1 overall, or ~34.5MPH @ 5500RPM

    You can swap out that 22T to something bigger (it takes #35 chain) for more reduction and takeoff or use a smaller rear sprocket for higher top speed.

    If you set your gear ratio too tall, you'll get some chatter off the line tho. 30MPH should be enough, unless you're greedy IMO lol
     
  15. Nehmo

    Nehmo Member

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    Those numbers are fine with me. I'll be happy to go 30mph (48 K/hr).
    The 56t sprocket attaches directly to the rear wheel, as I see. (In an electric bike, which I'm a bit familiar, a freewheel would be called for here, but things are different with gas-power.) It appears to attach as the brake disk does. Correct?
     
  16. The_Aleman

    The_Aleman New Member

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    There are several different ways to attach sprocket to rear wheel.

    1 - the (in)famous ragjoint. 2 pieces of rubber and some curved plates that attach the sprocket to your wheel. It works when done right and it's cheap.

    2nd, you can use a hub adapter. The adapter clamps to the bicycle hub and 3 bolts attach a sprocket to it. It's a step up from a ragjoint, but costs a lot more.

    3rd, you have the method you mention, sprocket bolted to disc rotor holes. it's probably the most reliable method and easiest to set up. Also not cheap, perhaps.
     
  17. atombikes

    atombikes New Member

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    4th,
    Lace a moped rear hub into your bicycle rim. Not necessarily cheap, and definitely not easy, but should be bomb-proof unless you are running a lot of HP
     
  18. azbill

    azbill Active Member

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    the EZM page is going through a major update ,,,
    there are a bunch of EZM dealers on this forum (myself included)
    I am sure one of us will be glad to help with any questions ;)
     
  19. Nehmo

    Nehmo Member

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    I just called (800) 661-KART(5278) for the third time (once per day) and left another message. Failing to return calls makes me a bit uncomfortable about the business skills of these guys. I'll try email.
     
  20. azbill

    azbill Active Member

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    AGK is a small shop and are usually pretty busy,,,
    I would keep trying the phone ;)
    they are VERY helpfull when you get in touch with them (^)
     

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