Been looking around on the site for a while and haven't spotted a complete 212cc build, i mean you would almost expect one on a stingray for a cruiser, why don't people put these engines on i mean they are what , 120 bucks at harbor frieght? seems like a steal to me so whats the hold up? Don't they push you at over 50 mph?
Why no 212cc builds?
- Thread starter OCC
- Start date
it aint just the cost of the engine either, its the motor mount, the transmission, the know-how to put it together and link up a throttle, and having enough room in the frame PLUS having a frame strong enough to take that beast. It aint as easy as you seem to think it is.
what do you mean "transmission" you mean a sprocket and a chain?
Couldn't the motor mount be easily put together with some metal and a welder?
And i'm guessing by reading this that linking a throttle is hard.
ha ha, a transmission for a 212 consists of a little bit more than a sprocket and a chain. First off you need a clutch. Secondly, you need multiple gears to get enough reduction to get a useable final drive. A transmission for a 212 is either going to consist of a belt primary and chain secondary, which can be something like the qmatic or a cvt drive, or a jackshaft, which is chain primary and secondary. You cant run one sprocket on the engine and another on the rear wheel with just one chain like you do on a china kit, because you wont have enough reduction. Most people use centrifugal clutches on the Predator engines, although I do believe an EZM silent drive will bolt right up to a 99cc, but silent drives are hard to find nowadays because they are not in production. But I dont think a silent drive will fit on a 212 anyway. There is a member here who built an in-frame friction drive with a 99cc predator using a belt straight from the shaft to the roller, but that wont work with chain drive. So no, a transmission isn't as easy as you seem to think it is. Yes, a motor mount can be made with a welder and some angle iron, several members here have done that, but again, it takes know-how. Linking up a throttle is not terribly difficult either, but again, know-how. Installing a Predator of any size in a bicycle is NOWHERE NEAR as easy as installing a china kit. With china kits, most everything is already done for you, its a simple matter of bolting everything up and making a few adjustments. Installing a Predator requires technical know-how and may require custom parts that you may have to fabricate yourself. Again I ask, have you yourself built a bike with a Predator engine?
no i havent built a 212cc build i just dint see why you could'nt use 1 gear instead of needing 6 gears it aint a racer
what he means by multi ratio is,in order to get a reasonable speed out of the bike, it cant be done with one ratio,unless you hade a sprocket like this
you would need a setup like the second pic i posted
you would need a setup like the second pic i posted
you dont need 6 gears, at the most you need 4, and here is how it works: shaft to input/output, output to rear wheel. the shaft is the first gear, the input is the second, output is the third, and the rear wheel is the 4th. with only two gears, say you have a 20t front gear, and a 56t rear, thats 2.8:1 final drive. I dont know how many rpm's a 212 puts out, but a 99cc with governor removed puts out between 5 and 6k. 2..8:1 @ 5k rpm is way too high. I dont have my gear ratio calculator in front of me to tell you what speed that would go, but put it this way. 10 or 11 to 1 gear ratio, which is much lower gearing than 2.8:1 would pull you between 35 and 45 mph. Thats what you need gear reduction for. as far as being a racer, there is at least one member here who has a 212cc that he races. you need to understand a lot more about gear ratio before you understand why things are not as simple as you seem to think they are. and you dont need a lot of cc to make a powerful engine. morini engines are 49cc and put out about twice the rpm of our little china two strokes. read up on gear ratios and rpm's a bit, and you will understand a bit better.
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I am buying the Harbor Freight Predator 212cc 7hp motor today on my way home, and then picking up a Schwinn StingRay as well. Total investment will be less than $200 when I am done. I was doing some calculations on a go kart speed calculator. Looks to me like this is totally feasible without a jack shaft or torque converter. Never built one before, but I have built plenty of motorcycles (I own a custom bike shop). Looks like the hardest part will be fabbing a mount plate for the motor, and that's a 20 minute job. There's a company that makes a sprocket adapter for the rear wheel of the StingRay that bolts to the hub - not to the spokes. Don't know what pitch the sprocket they sell is, though. I plan on getting their hub mount sprocket adapter, one of their sprockets, a bargain basement centrifugal clutch, and hooking everything up.
According to the go kart speed calculator, this is what I came up with me. Error check me, please.
Rear wheel circumference: 62.8"
Rear sprocket tooth count: 48
Front sprocket tooth count: 10
Engine max RPM: 3500 (The predator will turn to 5500rpm, but I will put a throttle stop in)
Top speed of 43mph. Anybody see any issues?
According to the go kart speed calculator, this is what I came up with me. Error check me, please.
Rear wheel circumference: 62.8"
Rear sprocket tooth count: 48
Front sprocket tooth count: 10
Engine max RPM: 3500 (The predator will turn to 5500rpm, but I will put a throttle stop in)
Top speed of 43mph. Anybody see any issues?
think how the $prockets line up. if the motor is anywhere near center ya gonna need a jack$haft. thats just the $tart. fir$t thing that ha$ to go i$ the flywheel you dont want a chineeze one flying apart between your leg$. there you just $pent more than the motor. and you havent adre$$ed $toping at 43mph time and time again. check out the racer bikes and notice some are building smaller motors. i got alot in jeffs old bike and it aint done yet. good luck. build and ride smart. dennis
Maybe its the way he came off or the words he chose, but am I the only one who thinks its odd that a person who has not built a 212cc bike and clearly doesnt have the skills or knowledge to (based on his difficulty understanding what I meant by things like transmission and gear reduction) is coming on here and basically challenging the whole community as to why we arent building monster motorbicycles?
The motor offset may cause you to ditch the pedals and thus cause
a shortened clutch life over a pedal start. The heavier you are the
worse your clutch life.
Rear spokes may need to be a larger diameter.
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I sign that. The transmission as Jackshaft alone cost more than the engine - without clutch.
Dont forget brakes, welding, and a whole truckload of small parts and details you dont even think about yet. Add shipping cost for all of that and before you know you are at 1500-2000 bucks.
But its so worth it h3ll yeah!
I personally haven't started with one because it's big and heavy, and I need to do a lot to purpose it for a bicycle.
That new chopper looks good though, I personally just want my bikes to be as light and narrow as possible.
That new chopper looks good though, I personally just want my bikes to be as light and narrow as possible.