First Build - Have Questions

[rking.1688]

I am looking to build a board track racer for tooling around town and running to work in on occasion. I would like it to get up to reasonable speeds, 55 mph at a good cruising rpm is more than sufficient. I have a Predator 212 motor I thought would work out at the farm. We bought it a while back and it never got used...so naturally it needs a good home.

My major questions:
1) What frames are out there that can handle that sized motor well?
2) Is there anything specific I should need to make that motor work for a board track bike?
3) Is it feasible (with modifications) to make that motor look period relevant?
4) Am I over shooting the capability of what should be done? (I know companies do build board track racers on bicycle like frames still)

Obviously it's not going to look as nice as a Harley V-Twin in a drop loop frame...but at least it puts it to use and I get some enjoyment out of it.

Thanks,
Ryan

 

[Timbone]

My opinions, intended to help:

1) None. No bicycle frame was designed to handle a 212cc motor. You hope for 55 mph? Fine, but use bicycle axles (only 3/8") at your own risk. Not beefy enough. Cheap front forks at 55? Not workable.

2) You'll need a centrifugal clutch.

3) I don't think so. Looks like a lawnmower engine to me...

4) Inly you know your skills, aptitude, and most important your bank account. There are no limits to what can be done. But that big motor pushes you over the edge and puts you squarely into motorcycle territory. License, tags and insurance required. Maybe even a safety check by the sheriff!

 

[KTOKTO]

Check out sportsman flyer's website and build it to no lesser quality.

btw. you aren't thinking clearly if you think cruising around on bicycle parts at 55mph is "sufficient" when those parts are designed for pedal power speeds.

 

[Jim Richardson]

Check out sportsman flyer's website and build it to no lesser quality.

btw. you aren't thinking clearly if you think cruising around on bicycle parts at 55mph is "sufficient" when those parts are designed for pedal power speeds.

I'm certifiable and I wouldn't want 55 on a bike frame. Good luck brother' JR.

 

[bakaneko]

I would take a slightly different answer. There are many 212cc Predator builds but they are done by folks with decent mechanical knowledge so if you are a total newbie it might be hard or near impossible to get it right and safe. Second, this is the 212 HF Predator with stock 6.5HP at MAX torque rpm; it is no where close to an entry level 250cc motorcycles with ~25HP and actually not even close to the 125cc motorcycles with 8.5-10HP. BUT, this is beyond many entry level 49cc motors here at 1.5HP, 66cc at 2HP, and custom 66cc motors here at ~4HP that most folks here use. That being said this is a challenge to get right and safe and you will or should use premium parts. Here are some points.

- having the engine is great but now you have to buy the parts which sometimes comes out to more than buying the damn kit (with engine) already
- 212cc Predator engines are used extensively for go-kart racing and many go-kart racing sites with have clutches, gas tanks, performance carbs, and performance exhausts for you. there was a really good one that i cannot remember off the top of my head
- many have said that the gear reduction box that is available for 212cc Predator motors can snap in half so you will have to find another or some how reinforce it
- 55mph on a bike is a disaster waiting to happen at the side of the road. unless you have the entire lane and know the street well I would not go 55 mph
- the Predator has a max rpm of 3500 so you need to figure out the correct gear ratio for that or remove the governer and even then the rpm will be low compared to most engines

So, it can be done but it requires skill, money, and research. My next build will be at HF 79cc Predator which is a bit more managable.

 

[Rusty_S85]

I would take a slightly different answer. There are many 212cc Predator builds but they are done by folks with decent mechanical knowledge so if you are a total newbie it might be hard or near impossible to get it right and safe. Second, this is the 212 HF Predator with stock 6.5HP at MAX torque rpm; it is no where close to an entry level 250cc motorcycles with ~25HP and actually not even close to the 125cc motorcycles with 8.5-10HP. BUT, this is beyond many entry level 49cc motors here at 1.5HP, 66cc at 2HP, and custom 66cc motors here at ~4HP that most folks here use. That being said this is a challenge to get right and safe and you will or should use premium parts. Here are some points.

- having the engine is great but now you have to buy the parts which sometimes comes out to more than buying the damn kit (with engine) already
- 212cc Predator engines are used extensively for go-kart racing and many go-kart racing sites with have clutches, gas tanks, performance carbs, and performance exhausts for you. there was a really good one that i cannot remember off the top of my head
- many have said that the gear reduction box that is available for 212cc Predator motors can snap in half so you will have to find another or some how reinforce it
- 55mph on a bike is a disaster waiting to happen at the side of the road. unless you have the entire lane and know the street well I would not go 55 mph
- the Predator has a max rpm of 3500 so you need to figure out the correct gear ratio for that or remove the governer and even then the rpm will be low compared to most engines

So, it can be done but it requires skill, money, and research. My next build will be at HF 79cc Predator which is a bit more managable.

Which is why I shyed away from the shift kit that I was thinking of doing on my current build. It ended up making the cost way more than I can justify. Plus for me my goal is to have a top speed of around 40-45 mph so when I cruise at 25 - 30 mph I am not running wide open thus I can ride the bike in one sitting burning the whole tank up without worrying about overheating the engine.

I did plan on using the Sportsman Flyer frame for my second build which would be a closer reproduction of a board track racer but this one I built now is like a mix between a board track racer and a cruiser. Plus its using a 69cc 2 stroke that I am hotrodding a bit.

 

[Deleted member 26224]

I built a 212 cruiser last year and have logged over 13000 miles on mine. I've seen practically every issue. My bike tops out around 60mph and gets about 50mpg.

Basically, you need to overbuild everything. This is a difficult build to do without a welder and grinder. There are however a few builders that I call "parts jockies" that merely buy parts to adapt the engine to the frame, and these parts will cost you.

A 10mm rear axle lasted me about 10k before it snapped. I've never had a problem with the front wheel except that it eats brake pads very fast. And frame cracks. I've had many using 80-81 Chicago Schwinn frames. My crack fix just cracked. All cracks except for one have been in the rear end. Not an accident but you feel it soon as it happens. I'm converting an old dirt bike frame to hard tail for use with the 212 now.

Wheels are important. I'm still trying to find the right rear hub. For a front wheel you want a double wall MTB wheel minimum, and for the rear a double wall with heavy duty spokes, and sealed bearings front and rear. And a quality front brake. I use the trp t4.

Problem with the 212 is it's torque. You must upgrade everything else to handle it.

 

[BlueFinisher]

isn't there a variable speed belt drive option for a 79cc 1/2"or 5/8'' shaft drive Engine?

 

[wheelbender6]

If this is your first motorized bike build, I suggest that you build one with a kit motor first, like an HS 49cc or China girl 2 stroke. A kit motor will show you all the basics and give you plenty of experience. Build the 212cc bike when you have more experience. Building from a kit first will save you some broken wheels, broken chains and clutches down the road.
I don't know which state you live in, but a 212cc engine in a bicycle is street legal in only a few states. Good luck.

 

[Frankenstein]

Check out sportsman flyer's website and build it to no lesser quality.

btw. you aren't thinking clearly if you think cruising around on bicycle parts at 55mph is "sufficient" when those parts are designed for pedal power speeds.

Where's Randall with that thing he likes to post?