KC's Big Red II 4-stroke shifter

KCvale

Well-Known Member
Feb 28, 2010
3,967
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Phoenix,AZ
I love this combination of parts for a legal (in Arizona) reliable 'powerful enough' motorized bike for getting around as fast you want to go in style and comfort.

Specs:

2013 steel frame Macargi Pantera 7S 7-speed beach cruiser.
- 7-speed derailleur hub swapped for a Nexus 3-speed internal shifter.
- Front fork replaced with a telescoping shock fork with V and disc brake bosses.
- Bottom bracket replaced with SBP wider dual sprocket freewheel crank set.
- 3-speed shifter moved to left side and plastic throttle and left grips replaced with foam BMX style grips and independent V brakes.

2013 Gasbike.net HS 49cc 4-stroke engine with 2013 Grubee centrifugal clutch 4G belt drive transfer case kit.
- Chrome long exhaust.

2013 SBP 4-stroke shift kit mounting base and jackshaft hardware.
- Added a right side spring tensioner for easy chain maintenance.





Rain or shine, really slow (pace a jogger) or really fast (~40) it does the job much like a motorcycle does with gears and comfort.

The actual bike frame style with fenders and such aside, I like the power plant and drive train a lot, any frame with at least dual V brakes and if you can a shock front fork and you'll be a happy rider ;-}
 

KCvale

Well-Known Member
Feb 28, 2010
3,967
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48
Phoenix,AZ
The actual displacement is 48.7 and no court in this state would ever screw with you over a fraction of a cc and with any luck my ongoing fight to raise the limit to 66cc continues to a reasonable limit change.

But that's OK MBR, don't comment on the build itself, just laugh at the .7 cc legality of it in my description of it and nothing else.

I am damn proud of how I build bikes especially motorized bicycles like this and share what parts I use and how I do it for others, you build however you want but was a laughing out loud at me icon really needed as your only comment for this build topic?

Well then, 'I fart in your general direction' sir. ;-}
 
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GearNut

Active Member
Aug 19, 2009
5,104
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San Diego, Kaliforgnia
That bike is beautiful! It is also basically what I want to build only using a SkyHawk GT2A-S frame.
Now I am on the fence about using the HS 49 or convincing a HF 79 to work.
On another unrelated note, What is your technique for reinforcing the fenders?
 

LR Jerry

Well-Known Member
Dec 19, 2011
1,153
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Rockwood, TN
Great bike KC. That's nice the bike legal in Arizona. Use the belt and pulley Kildoff auto shifter on the 3 speed hub, then you'll have a multi geared bike that'll be legal in a lot of states. Many of the states laws specifically state no manual shifting by the operator to the engines drive system. Or some say no external shifting device to the engine's drive system. Brian still has both rim drive and B/P drive auto shifters. It's a legal loophole we can take advantage of.
 

silvaire

New Member
Jan 25, 2009
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North of the Golden Gate
Great bike KC. That's nice the bike legal in Arizona. Use the belt and pulley Kildoff auto shifter on the 3 speed hub, then you'll have a multi geared bike that'll be legal in a lot of states. Many of the states laws specifically state no manual shifting by the operator to the engines drive system. Or some say no external shifting device to the engine's drive system. Brian still has both rim drive and B/P drive auto shifters. It's a legal loophole we can take advantage of.

I've never heard of a "Kildoff auto shifter", but there are a number of automatic Shimano Nexus hubs, such as this 3 speed one:
http://www.shimano.com/publish/cont...roducts/city___comfort_bike/auto_inter-3.html
 

LR Jerry

Well-Known Member
Dec 19, 2011
1,153
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48
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Rockwood, TN
I've never heard of a "Kildoff auto shifter", but there are a number of automatic Shimano Nexus hubs, such as this 3 speed one:
http://www.shimano.com/publish/cont...roducts/city___comfort_bike/auto_inter-3.html
I've done some treads on the Kildoff shifter. It's a mechanical auto shifter. There's been attempts with electronic auto shifters but from what I've read they just didn't work with a motorized bicycle. Adjusting what gears they shift at seems to be the problem. I use a mechanical auto shifter and have had success with it.

Eventually I'd like to build a full suspension automatic cruiser using a setup like KC has on this bike.
 

KCvale

Well-Known Member
Feb 28, 2010
3,967
51
48
Phoenix,AZ
Thanks to everyone for the kudos ;-}
That bike is beautiful! It is also basically what I want to build only using a SkyHawk GT2A-S frame.
Now I am on the fence about using the HS 49 or convincing a HF 79 to work.
Starting with the GTA2 frame with built in gas tank, or any bare frame for that matter, and building out is a good way to go about building a shifting bike like this for yourself if you have the bank or parts on hand to flesh it out.

That is the beauty of building for yourself first, you have all the time it takes to experiment all you want and why I have done the same thing with most every new system I tried, by building myself a new personal ride of the type first to see what works best before you offer them for sale.

In a production environment for customers with time constraints I find just springing for a known good bike base and then the kit boxes of parts with all the parts known to play nice together and avoid using a welder if possible.

I've done a 79cc 4-stroke Pred but that was a direct drive with a Q-matic and HD rear hub. It would wind up to a pretty decent top speed but I'd take this little 49cc 4-stroke with a 3-speed over it for daily commuting and it is a whole lot easier and less expensive overall to build with the perfect amount of most useful power for the task.

That and throwing 5 HP through even an HD jackshaft freewheel and bicycle back wheel gears (internal or derailleur) may just tear stuff up and that's no fun ;-}
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,508
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Ridin' inSane Diego, CA.
I'll take this single speed over any small 4-stroke shifter for commuting and daily fun riding. Who needs gears when you have over 6hp ? From take-off to top-end, this engine just pulls with no need to pedal ;) It's only 99cc (4-stroke) which is about equal to a 50cc 2-stroke.





If this bike had gears, I'd call it a motorcycle....

.wee.
 

LR Jerry

Well-Known Member
Dec 19, 2011
1,153
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Rockwood, TN
Who needs gears? Well let me answer that for you Scotto. There's three reasons I need gears.

Legal requirements:

Tennessee 55-8-101

(35) "Motorized bicycle" means a vehicle with two (2) or three (3) wheels, an automatic transmission, and a motor with a cylinder capacity not exceeding fifty cubic centimeters (50cc) which produces no more than two (2) brake horsepower and is capable of propelling the vehicle at a maximum design speed of no more than thirty miles per hour (30 mph) on level ground. The operator of a motorized bicycle must be in possession of a valid operator's or chauffeur's license, and shall be subject to all applicable and practical rules of the road. A motorized bicycle may not be operated on a highway of the interstate and defense highway system, any similar limited access multilane divided highway, or upon sidewalks;

My state clearly defines what a motorized bicycle is. Since no manual clutching is involved and my bike shifts 5 gears automatically I meet the automatic clause.

2) Weight issues:

I'm 6'2" and weigh 250 lbs. Lot to ask of legal 2 hp and under 50 cc gas engine.

3) Steep hills:

Where I live hills can be as steep as a 30% grade.


To conclude gears are for large people who live in steep hill areas and are legally restricted to small engines less than 50 cc. I'm sure others may have legitimate reasons for them as well.

Here in Tennessee the bike in the your picture Scotto it could be called a motor driven cycle since its under 125 cc. MDC need insurance and registration. You'd have to meet braking, lighting, horn and instrumentation requirements. You can't have them on an interstate. You'd have to state it was less than 5 hp. Even if with gears and you could maintain posted speed limits on any road a requirement to be considered a motorcycle. The frame wouldn't meet federal safety standards for a motorcycle. Don't get me wrong I like your bike. But here where I live unless your bike was declared a motor driven cycle it'd only be good for a race track, private property or off roading.
 
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scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,508
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38
Ridin' inSane Diego, CA.
Who needs gears? Well let me answer that for you Scotto. There's three reasons I need gears.

Legal requirements:

Tennessee 55-8-101

(35) "Motorized bicycle" means a vehicle with two (2) or three (3) wheels, an automatic transmission, and a motor with a cylinder capacity not exceeding fifty cubic centimeters (50cc) which produces no more than two (2) brake horsepower and is capable of propelling the vehicle at a maximum design speed of no more than thirty miles per hour (30 mph) on level ground. The operator of a motorized bicycle must be in possession of a valid operator's or chauffeur's license, and shall be subject to all applicable and practical rules of the road. A motorized bicycle may not be operated on a highway of the interstate and defense highway system, any similar limited access multilane divided highway, or upon sidewalks;

My state clearly defines what a motorized bicycle is. Since no manual clutching is involved and my bike shifts 5 gears automatically I meet the automatic clause.

2) Weight issues:

I'm 6'2" and weigh 250 lbs. Lot to ask of legal 2 hp and under 50 cc gas engine.

3) Steep hills:

Where I live hills can be as steep as a 30% grade.


To conclude gears are for large people who live in steep hill areas and are legally restricted to small engines less than 50 cc. I'm sure others may have legitimate reasons for them as well.

Here in Tennessee the bike in the your picture Scotto couldn't even qualify as a motor driven cycle because its over 5 hp. Even if with gears you could maintain posted speed limits on any road. The frame wouldn't meet federal safety standards for a motorcycle. Don't get me wrong I like your bike. But here where I live it'd only be good for a race track, private property or off roading.
Gee, I guess you do. Sorry to hear all that malarkey....glad I live where I do and ride what I ride. ;)

Anyone else?
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,508
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Ridin' inSane Diego, CA.
Your bike is not legal for on road use in CA.

Just because you haven't been busted, doesn't mean you won't be.
I'm good with that......next

And that's probably because I've been riding 2-wheeled bicycles around here for over 50 years and I don't ride like an idiot like 99% of the china girls running around here on the sidewalks and at night without lights (or mufflers). I've been pulled over, even on my 212cc race bike and had no problems.
 
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LR Jerry

Well-Known Member
Dec 19, 2011
1,153
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Rockwood, TN
In Tennessee you can voluntary register and insure a motorized bicycle but you don't have to. Seven years my X-brother-in-law and my brother were both charged with operating an improper vehicle on the public road ways. The bicycles were considered improper here in my state due to cc size and manual clutching.

What I like about KC bike is the look and with a Kilduff belt and pulley auto shifter it'd be totally level here in Tennessee.
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,508
6
38
Ridin' inSane Diego, CA.
In Tennessee you can voluntary register and insure a motorized bicycle but you don't have to. Seven years my X-brother-in-law and my brother were both charged with operating an improper vehicle on the public road ways. The bicycles were considered improper here in my state due to cc size and manual clutching.

What I like about KC bike is the look and with a Kilduff belt and pulley auto shifter it'd be totally level here in Tennessee.
Good to hear.....it's a nice set-up.
I don't use manual clutches on my bikes......yet. Motorcycles yes....not on bicycles.
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,508
6
38
Ridin' inSane Diego, CA.
KC or Scotto do either of you know what the torque limits are on the Shimano Nexus 3 speed hub?
I can tell you that a brand new Nexus 3-speed hub w/disc brake lasted one day of racing on a tandem powered by a Kawasaki 120cc 4-stroke engine. I raced it solo and was shifting smoothly throughout the day with no miss-shifts. 1st and second gear pretty much became one and would slip under power after that event. It sure was fun while it was working though.