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Old 10-15-2016, 09:21 PM
progrock progrock is offline
Motorized Bicycle Newbie
Join Date: Oct 2016
Location: California
Posts: 2
Thumbs up First build, cheap 2 stroke or expensive 4 stroke

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 ( ... 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, 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 ( 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,

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