670cc V-twin mini chopper beginning plans

xXNightRiderXx

xXNightRiderXx

Active Member
The Night Prowler

Frame: custom made soft tail chopper bicycle with 7 speed freewheel, pneumatic shocks, and seat post suspension.

Brakes: 180mm shimano hydraulic disk

Engine: 20HP 670cc V-twin Predator

UPDATED Gearing: w/ pedals, 52t driven chainring, 12t on the engine, 15t jackshaft in, 12t jackshaft out, 39t drive chainring, 30t first gear, 12t 7th.

UPDATED Clutch: 12t centrifugal clutch

UPDATED Wheels:[front] 700x38c custom five spoke w/ schwalbe CX tire
[rear] 26x3.8 , 6-10 speed freewheel and 7 speed cassette and surly black floyd 120tpi 26x 3.8 tire

UPDATED Gas tank: 5gal top tube tank with one two gallon reserve

ADDED Oil: 10w30 high mileage, including one two gallon oil reserve w/ hand pump

Handlebars: custom with 150mm rise

UPDATED Underglow led color: Red

Fork: 28 in. triple tree solid fork at 70 degrees

Bottom bracket: 230mm sealed bearing cartridge

Pegs will be 1 1/4 inch steel bar with grip spikes

Please take note that this will be my personal ride and will not make more to sell. I will build, for sale, no higher than the 420cc predator, for the daredevils and speed demons. Or even people who like risky machines... You never know.

I've decided that I will build these big bikes for sale, but they must be pre-ordered. The Night Prowler will likely cost me about $2000 total to build, and I charge $10/hr labor.

SAFETY WARNING: These bikes may go a top speed of 140 with a 7 speed drivetrain! Please practice common sense and caution. Inspect the bike before and after every ride, fill up, and rest break. A crack may appear in the welds, or at the mounts. If this happens, please take a photo with the serial number and I will replace your frame or fork at no extra cost. Also, please choose a name for your chopper for easier identification and for awesomeness points!
 
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Sounds retarded to me. 650 and a 700c wheel? You're thinking about the led underglow already? LOL
 
A V twin done right.
http://motorbicycling.com/showthread.php?t=32428

Four 5gal gas tanks????

I vote for Red, green, and blue LED's for that circus look!!!

attachment.php
 
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Dang, That's a good read and an awesome project.
"So after much back and forth about whether or not to use a Worksman frame I decided to build my own. "
Good luck, custom motorcycle builder! I'd love to see the mods you do to the Vtwin.
 
Tony01 said:
Sounds retarded to me. 650 and a 700c wheel? You're thinking about the led underglow already? LOL
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only the front is a 700c, and that wil be a 700x38c with CX tires. the rear wheel wil be a 26x4.25 with all terrain tires.

yes, four gas tanks for a total of 20 gallons, but this is my roadster.
 
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xXNightRiderXx said:
only the front is a 700c, and that wil be a 700x38c with CX tires. the rear wheel wil be a 26x4.25 with all terrain tires.

yes, four gas tanks for a total of 20 gallons, but this is my roadster.
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gas is ~ 6lbs per gallon so 20 gallons is 123lbs
How much dat little V Twin motor weigh?

20 gallons at 40 mpg is 800 miles. Do you have an 800 mile arse?

Four 5 gallon tanks would make one fugly bike but this bike is
never going to happen so why am I posting this?

Are you on drugs or did you start St Patty's day early? laff

seriously, this is an early April Fools joke, right? .duh.
 
600cc motorcycles have one tank bruh.

Those tires will explode with that weight

You need motorcycle wheels and thus a motorcycle frame

I mean, that one build did it with spoked wheels but I would not trust them one bit.
 
MotorBicycleRacing said:
gas is ~ 6lbs per gallon so 20 gallons is 123lbs
How much dat little V Twin motor weigh?

20 gallons at 40 mpg is 800 miles. Do you have an 800 mile arse?

Four 5 gallon tanks would make one fugly bike but this bike is
never going to happen so why am I posting this?

Are you on drugs or did you start St Patty's day early? laff

seriously, this is an early April Fools joke, right? .duh.
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No, this is NOT a joke. The engine weighs about 105 lbs, I weigh 120 at 5' 7", plus the fuel would make about 400 pounds, which is still half the weight of a normal motorcycle with that engine size. Also, did you not read the full plans? Soft tail with suspension seat post. I could ride thousands of miles on that bike.

Ultralight, most do. Not this one. Also, the 700x38c CX tire won't blow up from that weight unless I hit something with it. And certainly not a 26x4.25 tire. The spokes will be 12ga on the front, 10ga on the rear. Both will be 36 spoke wheels, but the rear will be laced cross four because it's more efficient and stronger. The front wheel will be laced cross three because it doesn't have to withstand as much stress.

I hope you guys think I'm an idiot for even THINKING about doing this insane stunt, but I looked for mini choppers with the 670cc, and none showed their blocks. I'm building the first of its kind here for all I know, and it will cruise, run, and sprint like it's full sized cousin. Sometimes, idiocy is the backbone of creation. .shft.
 
So basically you're building a small motorcycle(no pedals) with a large motorcycle engine?

Why do you need to carry 20 gallons of gas? Wouldn't a small motorcycle tank suffice?
 
5-7HEAVEN said:
So basically you're building a small motorcycle(no pedals) with a large motorcycle engine?

Why do you need to carry 20 gallons of gas? Wouldn't a small motorcycle tank suffice?
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yes, i am. a small tank would suffice, yes, but if you were planning a few road trips using this bike, wouldn't you want to carry as much as possible to get the most range you can out of it? besides, im putting one 5 gal main tank plus one 2 gal reserve on my street bike just for better range. Anyways, now I need to figure out the paint scheme. I'm going semi-gloss on everything, except trim. Trim will be chrome.

Here are the primary color finalists:
1) Black
2) Midnight Blue
3) Midnight Purple
4) Blood Red
5) Spruce Green

i also have several secondary colors to go with the primary:
1) Royal Blue
2) Dark Green
3) Violet
4) Silver
5) Black

must be two different colors, must choose two. please post your choices at the end of your replies.
 
I think you need to focus on more important things like the height of your ape hangers, the style and sound of your horn, and what color you're going to paint your wheel nuts. The most important thing is to look cool and have matching wheel nuts and valve cover bolts. This is the stuff people notice.
 
No ape hangers for me. It'll be swept Cruiser bars with black leather tassels, the nuts will match the paint scheme, but will be spikes. The valve caps will be pressure sensitive for maintenance purposes.

The horn I haven't decided on. Perhaps an air horn? Definitely going to be marine. Ghost flames will be glossed into the clear coat on the gas tank. I think I may have a bobber with the bike's name on my rear wheel in calligraphy.

I may have to find a way to get a sponsor if I'm going to do this without completely doing it myself. I can't paint, I can barely weld, I'm just a mechanic. And I can barely do low voltage system repairs, let alone completely assembling one. I'm good with wires, that's about it.

I still can't decide on a torque-a-verter or a standard centrifugal clutch. I just don't know which is better for variable terrain and traffic speeds. I also want to race this at some point, so should I get both so I can adapt, or just get one for both?

As for the fork, it comes chrome, so should I strip, smooth, and paint the fork, or just leave it chrome?

What can I do to improve performance on this engine? I'm going to have long muffler pipes with one of two muffler types. There is absorption and reflection. One is quieter at all speeds, one is louder at higher engine speeds. Which would be best for this?

I didn't post this before, but I'm also building this to impress motorcyclists. Right now, they see my bike and laugh. I want them to go Woah! Hehe.
 
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Extreme long range adventure bikes have 4.5 gallon tanks, and go over 320 miles. I'll be darned if your bladder lasts that long, let alone 1,500. That's about 16 hours of drive time.
The weight of 20 gallons would make your bike less fuel efficient by a considerable margin.
Plus, it'll be more than your average car in price to fill up. Where did the $1.50 tank fill ups go?

All this said, definitely black and royal blue.
 
ultralight01 said:
Extreme long range adventure bikes have 4.5 gallon tanks, and go over 320 miles. I'll be darned if your bladder lasts that long, let alone 1,500. That's about 16 hours of drive time.
The weight of 20 gallons would make your bike less fuel efficient by a considerable margin.
Plus, it'll be more than your average car in price to fill up. Where did the $1.50 tank fill ups go?

All this said, definitely black and royal blue.
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I see your points here. how would a 5 gal top tube tank with a 5 gal reserve and a 5 oil change tank impact my bike?

How should the tanks look? streamlined, clunky saddlebag tanks, or should i design the tanks together like fenders?

I like your color choice. lets see what other color combinations people come up with?
 
Oil change tank? You're talking like this is a zombie apocolype self reliant getaway bike.
10 gallons total in gas is much more reasonable. I'd put one around/on top of the top tube, and one around and behind the seat. They'll need to be custom, and I wouldn't worry about them till after you have a working bike.
 
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ultralight01 said:
Oil change tank? You're talking like this is a zombie apocolype self reliant getaway bike.
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that's because it kinda is a self reliant getaway bike, lol. Lets say you are on the lam, you can only get enough cash to maintain your bike and to put a few gallons in at a time. its about time you got an oil change. why buy oil every time you make the change? 5 gallons is enough to ensure you won't need to buy oil for a while, and all you would need to do is drain your current oil, reattach the cap, and open the valve. the oil will flow from the container into the engine. I'm designing this bike to be able to run on a very low budget. the oil tank will be identified by a yellow stripe at the bottom front of the tank.

Yes, 10 gallons is much more reasonable. The top tube itself will be the main tank, and will look like the hood of a cobra, sheltering the engine from things falling onto it, while also providing a crush zone in case i lay it out. Its the reserve tank and the oil tank im trying to figure out.

I'm thinking the shifter should be a foot shifter, and the rear brake actuated by the left foot, using the right to shift, just like a motorcycle. so yeah, im definitely building a little big cycle! I will have to plan out placement once i get the frame built. thinking of just buying a welder so i don't have to dish out extra just to have it built for me.
 
Definitely buy a welder. But, you know what?
The predator V twin is garbage.

Under $500 you could buy a used motorcycle engine with the same displacement and more power.
A predator will offer low rpms , and you will HAVE to build your own external transmission, which will be a massive headache and not really last.

The engine won't really last either.

You can get more speed, a real, reliable trans, less weight, better fuel economy, and better quality out of a motorcycle engine.

Please go that route. I looked at the vegas Craigslist, and there's some good options. Or you could buy a parts motorcycle and tear out, not only the engine, but the tank, lights, etc.
 
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I still think you'd be better off with an engine with a smaller displacement, but a built in transmission. You'd get better mileage and go faster. My 125cc lifan can go 68 mph with current gearing, and if I changed the gearing it could probably hit 100 mph. It also has enough torque to wheelie and leaves cars in the dust at the stoplights. I think there is also a 250cc lifan V-twin that can be had for about a thousand dollars, buy that and you won't need to design a transmission.
 
ultralight01 said:
Definitely buy a welder. But, you know what?
The predator V twin is garbage.

Under $500 you could buy a used motorcycle engine with the same displacement and more power.
A predator will offer low rpms , and you will HAVE to build your own external transmission, which will be a massive headache and not really last.

The engine won't really last either.

You can get more speed, a real, reliable trans, less weight, better fuel economy, and better quality out of a motorcycle engine.

Please go that route. I looked at the vegas Craigslist, and there's some good options. Or you could buy a parts motorcycle and tear out, not only the engine, but the tank, lights, etc.
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please elaborate on how the predator is garbage? I haven't heard very many bad things about them. I'm not really worried about weight, or the tranny, I just want a good powerful engine that rumbles and roars.
 
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