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Keaven

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I have a buddy who wants to build a motorized bike. He is leaning towards a two-stroke which fits in the main triangle and runs a chain. Anyone here have any experience with any of the engine kits which are currently available and any recommendations?
Thanks!
 
There's a few folks here into the motorized bikes. Check out kingsmotorbikes.com they shipped me my 80cc in 3 days. Also check out motoredbikes.com a comunity of friendly people who will answer all your questions.
 
yeah, the rear rack-mounted engines just don't look as good as the little in-frame Chinese 2-strokes that most peeople are using, plus those little 2-strokes are usually cheaper. i'm waiting on an Italian 49cc 2-stroke at the moment.

lots of nice, helpful folks at motorbicycling.com with good info and plenty of interesting projects.
 
I've been building and working on motorized bicycles for a couple years now and this is what I have found.

Pros of the 2 stroke:
Faster on top end with the stock drive gear.
Cost less then the 4 stroke
Easier to rebuild if you blow it up.

Cons of the 2 stroke:
Mixing gas
No torque at start, you have to pedal up to speed then drop the clutch to start it. Sadly if something is wrong and disengage the clutch you can throw yourself over the handlebars when it doesn't kick in. I've seen it happen.
They are overall really finicky. Finding your top performance tuning is difficult.

Pros of the 4 stroke:
No mixing gas. You just fill the oil pan, fill the tank with gas and go.
High torque. With the stock gear you can climb hills and start from a stopped position with no problems.
Using a 36 tooth drive gear I can easily push 45 and I weigh 250lbs. You loose a little torque but you can still go from stopped without pedaling.
Pull start, this is a huge benefit, trust me.
Extremely easy mounting, a can install one in 15 min.

Cons of 4 stroke:
Proper brake in procedure takes about 24 hours. You fill it with oil, let it idle through a full tank of gas, dump the oil, fill it all up again and repeat. You will notice metal dust in the first change, nearly non in the second change. If you do this it will last forever.
Without upgrading to a freewheel drivegear or disengage kit you have major engine brake when you let off the throttle.
Harder to work on if you blow it.

I recommend the 4 stroke. I have a 4 stroke on a Phat Cruzers cycle, with a 36 tooth freewheel drive hub, 40 spoke rim with 12 gauge spokes. I push 45 easy, plus I hooked up a flame thrower to the exhaust so I can throw flames 10 ft out the extended tailpipe.

it rocks.

http://www.bicycle-engines.com/

This is my main supplier for my kits and parts.
They are sold out until late september. They have 2 40ft containers on the way.
 
i agree with what Matt says and i bow to his experience, but 4-strokes (which i'd prefer) tend to be heavier and i haven't seen one that didn't have all that cowling on it. as far as eye-appeal, IMHO, the available 2-strokes look more like a small motorcycle engine, and less like lawn equipment. of course, that may not be a consideration for everyone and certainly no offense is intended.

i actually like the idea of pedal/roll-starting the engine like the Chinese engine riders do, but my Italian Franco Morini engine will have a kickstart and centrifugal clutch. like i said, i'd prefer a 4-stroke, but the engine i've ordered should be (i'm sure hoping!) a good compromise between the cruder China Happy Times engines and a small 4-stroke. having said that, though, there's some folks over at motorbicycling.com with lots of miles on the little HT engines.
 
I bought a 2 stroke from boygofast Runs great. plenty fast . Easy to hook up. I got the 70cc. look him up. .Fast shipping also. Bartleydad
 
Last year a close friend of mine decided he wanted to put an gasoline engine on one of his spare bikes. Another good friend had bought from me a really nice barn find 52' Wizzer that I had rebuilt and modified into a sweet little mini chop. After looking for a few weeks for another Wizzer 4 stroke motor we figured out that two strokes were much more plentiful and more affordable. Wizzer motors are expensive but worth it! So we bought a 2 stroke kit from King for $225+ shipping and put it in a Micargi stretch low-rider cruiser. Right off the bat we had problems. King gave hardly any explanation on how to install in this frame even though they had the exact same bike showing a kit fitted on their website.

I build custom motorcycles all day long from vintage and sometimes obsolete parts so making something work is not a new concept to me but it was my first experience with the Chinese expletive, expletive. After finally figuring out how the bike was supposed to start, run and idle, we figured out that the Chinese chain was too short and the sprockets were like nothing "off the shelf" in America. Only after a couple of weeks research was I able to find the correct chain at of all places a machinery supply company. After it was all said and done we had over $400 just in getting this 80cc two stroke set up and it hadn't even run yet. So I get it running and this little motor vibrates so much that it breaks the frame at the engine mounting points within an hour of the first start up.

So the project got put back in the garage for several months and when my buddy got another $35 cheap bike through Craigslist we transfered all the parts and pieces over to the new standard cruiser frame and hoped for the best. Believe it or not this time around it does work better but it still suffers an extreme vibration between 12 and 20 MPH, once you get past 20 it will smooth out a little but it still sucks getting there. The vibration is severe, enough to numb the lower extremities within a 15 minute ride. I don't think anyone of our friends has ridden this bike for more than a whole tank worth of gas, it will rattle loose your nuts, bolts and even your fillings.

It's really funny but that 1952 Wizzer will start up and haul something serious all the way to 45 MPH and not vibrate more than a Vespa scooter. Maybe four strokes are the better answer but with all the State laws on the books regarding engine displacement the whole reason for a motorized bicycle was to skate around those licensing laws. Almost textbook the individual state laws states that any motor capacity exceeding 49.99cc regardless of two or four stroke will require licensing and registration, and I know that some states like here in Cal if its got a motor its a motor vehicle and the state wants its cut, so pay up! Most all of the four strokes are like 125cc as the smallest and the Wizzer's are 150cc to 175cc so unless you think the cops aren't interested the laws on their side not yours and stupidity is not a very good defense. I know from experience!

Good luck and I hope this answers your questions.

Later Travis
 
Almost textbook the individual state laws states that any motor capacity exceeding 49.99cc regardless of two or four stroke will require licensing and registration, and I know that some states like here in Cal if its got a motor its a motor vehicle and the state wants its cut, so pay up! Most all of the four strokes are like 125cc as the smallest and the Wizzer's are 150cc to 175cc so unless you think the cops aren't interested the laws on their side not yours and stupidity is not a very good defense. I know from experience!
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The chinese 4 stroke kits from bicycle-engines.com are all 49cc motors. Unless you get the Honda model, it breaks the 50cc barrier.

As far as the vibration problems... 2 strokes are renoun for the shakes. The only way to reduce them is to 1st, replace all the stock nuts and bolts in the kit with american good quality nuts and bolts. 2nd, make sure your mounted as solid as possible. Some people slack on this. The usual frame will accept the seatpost mount with no problem so people slack on the downtube mount. The downtube mount is where all vibration problems arise. A good amount of frames are not spaced exactly right to accept the front mount. I've seen two solid solutions to this issue. The first is replacing the front mount studs with longer ones that reach past the frame, and getting a small block of aluminum machined to make up for the gap. This can be a little more costly if you don't have the right connections. I've seen it done with a block of aluminum and a hand grinder too. It depends on how diligent you are. The second solution is to make a bracket that turns the two studs into one that will mount through the frame. If you go this approach buy some tube stock that's the same diameter as your downtube. Cut the stock at 5 inches or so, then split it in half longways. drill a hole in the center of each piece so the single stud will pass through one half of the stock, then the downtube, then the other half of the stock, sandwitching the downtube in a "sleeve", Tighten nuts on to either side and that should reduce the amount of vibration in the bike.

It's always a good idea when building a motorized bicycle to strip it down and rebuild it using loctite on EVERYTHING. No matter how much of the vibrations you reduce or eliminate most bicycles are not made to handle the speed that they can get up to and will rattle loose.
 
my brothers been lookin for info on his chinese 2-stroke on the legality, as far as cops are concerned, in illinois, if it has pedals ... its a bicycle. as long as your not being a fool, nobody will look at you too hard.
 
CCR said:
my brothers been lookin for info on his chinese 2-stroke on the legality, as far as cops are concerned, in illinois, if it has pedals ... its a bicycle. as long as your not being a fool, nobody will look at you too hard.
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and be sure to make some 48cc stickers for your "motor-assisted" bicycle :)

my Franco Morini 49cc 2-stroke arrived this week; hope to have it grafted on to my rat soon:

fmorini.jpg
 

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