First build, cheap 2 stroke or expensive 4 stroke

Discussion in 'Motorized Bicycle General Discussion' started by progrock, Oct 15, 2016.

  1. progrock

    progrock New Member

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    Hey guys,

    After a few days of research, I am determined to tackle my first motorized bike build... though I have yet to decide on anything specific yet.

    I figure I'll start with the motor/kit first, then find a bike that suits it. Been checking craiglist for bikes, but I think the kit I get is gonna have a pretty heavy influence on my choices.

    I'm really hoping to build something that could do something in the 30-40 MPH range... I'm 160lbs, so I'm hoping that'll help things a bit. I think I'll mostly be riding on flat terrain (at least if I use it for my 4 mile commute that I currently ride my fixed gear daily). But there are also so decent hills not far, and I'm thinking I may enjoy a motorized bike so much, that I may want to explore a bit more.

    Since this is my first build, I was thinking about going with a SkyHawk Angle Fire GT5A 66cc Bicycle Engine Kit (http://www.bicycle-engines.com/SkyHawk-AngleFire-GT5A-66cc-Bicycle-Engine-Kit.html) ... I've heard good things, and it is damn cheap. I would be considering their 4 stroke kit, but it's not in stock, and waiting to hear back if it's gonna be a week or 2 wait, or if it could be months... I'd like to get started sooner than later... I can always do another build after this one (and I have a feeling I likely would if I got a cheap kit like this).

    Now if I went that route, I think I would want to put it on a pretty cheap bike... either a craiglist bike... or possibly even a bikesdirect or walmart, <$300 bike. I'm assuming single speeds would be much easier to do an install on, so been looking at some beach cruisers (tho I'm usually not a fan of the way you ride them, nor the handlebars... BUT, thats for a conventional bike.. I'm assuming adding a motor, and minus the pedaling, and what I like then may be drastically different). Definitely open to recommendations here. I'm also worried I may have to upgrade enough part (wheels, brakes, etc) that it may make sense to do a more serious build to start.

    Now my second choice, that I'm getting real tempted in doing, is to build a motorized bike that I am going to be much happier with. I'd like something reliable, and also not too noisy, while still getting the 30-40MPH speed I'm hoping for. 4 stroke kits are really appealing.. especially since I could fill them up mid ride without any hassle of mixing in oil... and I hear they are quieter and more reliable. The GOLDEN EAGLE KIT – 38CC 4 STROKE BICYCLE ENGINE – 36 SPOKE looks like a pretty awesome kit (though it is really pricey compared to all these chinese kits). But I also suppose I DO have the money to spend, and they seem to be pretty easy for a first build, and much more reliable. I also think their mounting style gives me A LOT more choices when it comes to bikes... which would allow me to get a good deal on a nice second hand bike off craigslist (tho also considering a new bike, maybe a ~400-500 bikes direct bike). I'm thinking maybe more of a mountain bike style frame (again not a huge fan of the beach cruiser handlebars... BUT thats when thinking of conventional pedal riding). Bikes direct also has a few single speed mountain bikes, I was thinking they might be a good choice for something like this... tho I think craiglist will be my first hope (Anything specific I should be looking for?).

    I also found this custom build instructions, http://www.instructables.com/id/79cc-Motorized-Bicycle-From-Scratch/?ALLSTEPS for a 79cc Predator engine (which I could get brand new today for $99) which sounds amazing. That write up got me really excited.. but I think it may be just a little too much work for me for my first build. But this got me thinking...

    Do you think it would be possible, and relatively easy, to get the GEBE Mount kit (https://www.bikeengines.com/shop/mount-kit-only-without-the-engine-36-spoke-2/) and put the 79cc predator engine on it? I feel like that would make me extremely happy, would likely give me more power than the minimum I am looking for (which I would not complain about)... and since I can get the engine for $99, would actually be close to $100 cheaper than getting the complete kit with a 38cc engine. I'm assuming the 79cc would be a decent amount louder, but for twice the horsepower, might be worth it (I just don't want to raise too much attention from the cops out here).

    Anyway, I'm totally open to other suggestions, but would love to hear what you guys think. I'm no expert on motors, but I am an engineer, and do have access to a pretty good amount of tools... but also looking for something not too hard for my first build... once I get this done, and if its "lacking" I will likely move on to a second build. BUT it would be pretty cool if I could build something I really liked my first go. I'm looking for advice on both motors and kits as well as potential bikes that would likely be good fits for whatever motor/kit I end up getting.

    Thanks in advance for any advice,

    Bob
     
  2. Agreen

    Agreen Member

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    If you have the funds, build it the way you want it. If you don't like a cruiser, don't build on a cruiser. If you like 4 strokes (I prefer them too) then use a 4 stroke.

    The HF 79 is a fantastic engine. You can mount it with only a centrifugal clutch, or hook it up to a cvt for higher speed and better takeoffs. I have a cvt on a Honda 196cc engine and it's great. It cost under 80 bucks on eBay. It's all about what you want.
     
  3. progrock

    progrock New Member

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    Agreen, thanks for the response, though I don't think you fully understood me. Of course I am going to build what I want, but since this is a first build, and I don't have the option to take up a workbench/garage for weeks, I need to figure out practical options of what to choose.

    First off, I have thrown out the idea of buying the cheap $150 2-stroke SkyHawk kit. I might get one of those later on for a super cheap build to tinker on (and maybe a great option so a friend can ride with me occasionally). But I will worry about that another time.

    So the HF 79cc predator engine should be able to mount to the GEBE mount kit with relative ease? Do you think I'll need anything else to make this work with the kit? (I'm hoping to complete the build in a day or two once I acquire all the parts, so it's important I plan/prep as well as I can). I'm worried it might be a little large, but if that kit will hold it, since it's a rear mount, I guess that shouldn't be too much of a concern. I'm also a little concerned that it may be a little loud... but hoping that's something with a little tuning and additional parts, I may be able to reduce noise a bit. I love the abundance of resources on the HF 79cc, it seems like it'll be a great pick.. and it's only $99 from Harbor Freight (plus I happen to live only a couple of mile bike ride from a HF store). I'm also a little concerned with the way this kit applies power to the wheel, definitely seems like some really serious spokes will be needed. I'm thinking it may be good to buy a rear wheel from them (tho I suppose if the bike I buy has a wheel that works, maybe I should go with that, and then if/when something goes wrong, get a new wheel... either one they offer, or if I find something even sturdier, go with that)

    If the GEBE kit didn't work with the HF 79cc, I also found a pretty cool rear mount, chain drive kit from these guys http://www.thatsdax.com/KIT_REAR_MOUNT_CHAIN_DRIVE.html I her good things from them (their kits, and support are apparently much better than their website building skills).

    Anyway, getting pretty excited about this, now if only I could find a solid bike. Luckily I'm in the SF Bay area where there are lots of used bikes for sale (Tho tons of people seem to want $10 less than the bike cost brand new... even for older 10+ yo bikes... but those people I don't even bother with)... sadly almost no one is responding from craigslist, not to mention, I have yet to find something that really stuck out to me. I think a 26" inch steel frame, with front suspension mountain bike or commuter is gonna be my first choice right now. I also need to look into what I need, and how much effort it takes to convert these mountain bikes or similar inso single speeds (presumably that will make things much easier to add a motor to). I actually have a pretty nice Felt single speed steel frame road bike (but I ride it as a Fixed gear with clip ins and no brakes... so planning on leaving that as it is, I love riding it).

    Thanks again for the help, all advice is welcome.
     
  4. Kioshk

    Kioshk Active Member

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    The only 196cc Honda engines I can find are over $500. You got a link? Did you mean the CVT was <$80?
     
  5. Agreen

    Agreen Member

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    Yes, the cvt was <$80. The Honda gx200 was free! A neighbor had a bad pressure washer pump and was throwing the whole thing away. I ended up making the bike for free. Long story, but I bought everything I needed with money I made from roadside finds. Weedeaters, leaf blowers, etc.

    That mount kit would be of little use with the HF 79. The only thing you might use would be the sheave (the thing the belt turns on the rear wheel). If you want to use a sheave, they're sold separately without having to pay $400 for a kit. I forget who makes it, but there is a HF 79cc jackshaft kit avaliable. I'll see if I can find it.

    (Edit, I found it)

    AGK sells them, and you can find them on ebay or gasbike.net. Get you a mounting plate for the engine, a rear sprocket adapter, some 41 chain, a gas tank, and a twist grip throttle, and you'll be set. A bike with GOOD brakes are a must. (Coming from the guy who only has a rear coaster on his 196cc bike)

    http://www.affordablegokarts.com/mm...de=A&Product_Code=12390&Category_Code=MTRBK79
     
    #5 Agreen, Oct 16, 2016
    Last edited: Oct 16, 2016
  6. Tony01

    Tony01 Member

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    Get the 79cc predator with the jackshaft kit, and buy or build a rear wheel with a moped hub; get a front disc setup off a mountain bike. Cost around $700 total and be a heck of a lot better than a 2-stroke. 2-stroke builds tend to be based on the 30 guarantee: 30 seconds or 30 yards, whichever comes first.
     
  7. TheNecromancer13

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    Hi Bob, I see you've found the forums! Welcome! Just wanted to say that you can get the same jackshaft sold by AGK for about $20 cheaper if you buy it from GTC manufacturing instead. Also about the noise, the 79cc is quieter than any 2 stroke bike I've ever heard.
     
  8. TheNecromancer13

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    The 30 guarantee... Ima have to remember that one.
     
  9. Slowbuild79

    Slowbuild79 New Member

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    Here's a pic of my 1st really slow build, almost a year lol ....4 stroke 79cc hf engine. Almost done waiting on the front wheel ....can't wait to get it done already...
     

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