Hello, First newbie "Project 55" - RockHopper Frame + Variable Drivetrain

C

cmanns

New Member
//I don't know if this is right section, if not could mod move and snip this?

Let me start off with the basics for "Project 55", I'm posting here for tips and build thread. I'd also like to do it as cheap as possible which I suppose DIY is that route lol, I got the bike for 20 bucks per instance.

  • 55MPH, may sacrifice for initial runs.
  • RockHopper 26" wheel frame - not sure of any other details, still waiting for the rims, fork, and handlebar.
  • Wheels are Maxxis Minion DFH 3 ply, look a few years old but in great shape.
  • Idealy Electric start, and non interfering drive from the engine so I could have it running and take off without pedals, or turn it on while already riding and go up a hill.
  • ^ So obviously will need variable drive, but not sure if that will happen initially.
  • In the future, I thought up a front wheel electric drive setup which would be powered by batteries charged by the engines alternator. AWD bike? :D

Do I really want to hit 50 ish? Sure, I've gone over 40 on a bike and it's not too bad, pedaling it is but if I had an engine in the back roads that'd be quite nice.

Currently I'm stuck at what engine I should put on. I'll measure the frame and update in a bit at how much space I think could fit but it looks like those small 8 hp or w/e 300~cc diese's would fit, theres almost over a foot of space from above the crank gears to the top part of the frame.

However budget is my issue atm, so looking at modifying a lawn mower engine. Sadly last offer didn't get a reply, was a Scotts lawn mower engine that appeared like it'd fit no problem and could be converted horiz shaft, had electric start, 6.5hp, and a separate drive which I wanted to do an alternator.

The only ideas I got for drive is below, I've also herd you can dual sprocket internal shifting hubs instead of running motor to crank but that was a year or two ago havn't found it again.
I found http://www.sickbikeparts.com/catalog/index.php?osCsid=s8h7qkrv286jlgrvgbkjao5o90 awhile back.

Last question to wrap it up in one thread, this would majorly turn the route of my bike. Do cops really bother you guys running a working pedaling bike with a larger then XxCC engine, I'm in calif and I've seen people cruise by downtown areas with crazy huge mower engines and such past cops and nothing. Not sure how they'd feel about me fallowing the 45mph speed limit on a back road though he heh .shft.

Edit: http://www.chp.ca.gov/html/motors.html

Appears they changed the laws, I'm going to try to find local people and ask. Appears no CC size gasoline engine is legal without license.
 
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55 is a crazy number
im scared doing 35 on my road bike

but

the HF predator is like 7 hp, and cheap, its not electric start but thats alot of extra weight you need to carry around (battery, starter, electrics)
with speed you need lighweight bits

with a torque converter and proper single speed gearing i dont see why you cant easily hit 45 mph but that ish is nuts your better off with a namebrand moped that somone has already soupped up

welcome to the boards
 
pocdragon said:
55 is a crazy number
im scared doing 35 on my road bike

but

the HF predator is like 7 hp, and cheap, its not electric start but thats alot of extra weight you need to carry around (battery, starter, electrics)
with speed you need lighweight bits

with a torque converter and proper single speed gearing i dont see why you cant easily hit 45 mph but that ish is nuts your better off with a namebrand moped that somone has already soupped up

welcome to the boards
Click to expand...


Yeah I changed my goal quickly after reading here.

Never known any MB'ers just a few people with scooters over the years.

Looking at a friction setup, got a thread in the Mountain Bike setup about ideas before I get started, Then I'll do a build thread.
 
It's more so a hobby of just putting the bike together.

Discovered the exhaust leak, now to make some gaskets.

IFmHd.jpg


Edit: Made some exhaust gaskets.... we'll see how they hold up :D

http://i.imgur.com/ZBRA6.jpg

Another edit:

She's together! :D

9pqtDh.jpg

5pOBVh.jpg


Just need to figure how to mount the side arms, chain has nice tension but slightly pulls it down, once left and right side arms are mounted stiff and chains put on it'll be sturdy. As is seems sturdy enough to ride but I wouldn't want to hit any speed bumps.
 
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Yea, if you want to do 55 then it won't be a budget build. I'm shooting for 45 with my 99cc predator, I also have a 90's rockhopper and I am building a custom cast aluminum engine mount for it. I have a parts list in my head, but my wallet hurts... I am trying to make as much as possible from cast aluminum because its free for me. The problem is no machine shop...
 
young grease monkey said:
Yea, if you want to do 55 then it won't be a budget build. I'm shooting for 45 with my 99cc predator, I also have a 90's rockhopper and I am building a custom cast aluminum engine mount for it. I have a parts list in my head, but my wallet hurts... I am trying to make as much as possible from cast aluminum because its free for me. The problem is no machine shop...
Click to expand...

How are you making it from cast alum?

If your able to pump out another if it's similar mount for rockhopper that I could mount a plate on. I can mount this motor in frame I just need to figure out clamp mounts and then bolt to the plate the engine sits on.

Edit:
Also yeah I don't know if I want to go over 30 with this frame till it's got front suspension and better mounts, most likely in fame. Are they steel or alloy? It feels some what strong. I went with a 33cc motor because of shipping 2 strokes to CA and my budget. It's later planned to slowly adapt another motor. Then keep this one still over rear powering an alternator, charging small pack of batteries. That will be for 2013 though. I just checked in the engine exhaust port, it's spotless, I expected a somewhat used carboned up motor to tune up take apart and play with but I guess it might run good.
 
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I built a small foundry. I am going to buy some new equipment soon, like a graphite crucible and professional high surface finish molding sand. For now I have to sand and file a lot, but that's what my apprentice is for! I give him the jobs that you can't really mess up. These frames are made of chrome moly, its pretty strong stuff but hard to weld. I am doing a production run and selling theses on eBay once I finish my prototype, should be tomorrow or early next week. Look at this thread: http://motorbicycling.com/showthread.php?t=40380
I never made the clutch covers because nobody seemed interested. Maybe I will do one so people can see it and want to buy one, idk. I am about to put up a pic of the first part of the mount that I cast on Wednesday. I am doing heat treatment on them, full T-6. I am using high strength zinc plated steel 8mm threaded rod for the clamps, 2 sets per clamp. Since the hardware is cheap when I buy bulk, I want to keep the price under $50 plus shipping so lots of people will buy it. I hope your my first customer! It will fit you bike very well. What size frame is it? Mine is a 17 inch.
 
Got riding today. The over-rear mount is slowly bending which throws the chain. Def need to get the side arms mounted. Only logical way is to drill the frame though >_>

I think it may however be the chain links, 1 or 2 are sort of stiff from being resized. I just need to slide the pin back and forth and break em free but not sure if that throws chains. I can lift the rear off the ground and spin the wheel up fast and it spins decently, can even let it touch the ground and it'll spin for a bit but I wasn't full throttling it cause I don't want to mess up anything if it flew off lool. Now that I moved the arms away up in the air, bent the tire guard thats below the rear mount since it was too difficult to remove and it was touching the tire. I was able to ride mostly motor power for 10 mins before a sudden DINK ROOOM and then had to pop chain back on >_>
 
With a GP460 and a nexus inter3 trike tranny, you can break 55 easy. I can break 40 with a tired 49cc in third gear just over 7200 rpm. The gp460 would drive that up to 10,000 rpm Im sure, and bust through 50 mph.

Im saving my monies to replace this old goat with some bigger torque.

Notice the three-speed jack-shaft that drives the sprocket. Do the math. 9.5 inch tire uses 16-tooth driver. 12.5 inch tire on it now is using a 20-tooth driver. I think a 26 inch tire would use a 40-44 tooth sprocket to achieve the same power drive. I will always advocate the light 2-stroke combined with the light manual 3 speed jack-shaft to achieve performance. This set-up is road proven through 3 different builds. Using kmc510 chain, I can ride for hundreds of miles without adjustment.
 

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You'd use the manual jackshaft over a shift kit?

Is a good idea though, I'd need to go with jackshaft once I put an engine in frame, might be complicated to fit with engine over rear...

Also what cluthc output is the GP460? Will it fit a 78mm clutch like scooters ususally use? if so it' d bolt up to the gearbox I currently got. Only issue with this engine is it very much lacks torque. You can hold it and take off on level ground, any sort of incline a tall, even like a speed bump lower then 5 will slow it to a stop, once your jamming it'll go up pretty steep inclines with just moving the pedals, I went up one hill on only it's power but I was already going like 15. Need to find what rpms I'm at though soon
 
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Yup, same bolt up pattern. And yup, I would build another one of these any day of the week. Would not consider the 'shift kit' on a bike at all compared to this. Double check the parts list between the simple jack and the full on shift-kit. This tranny is about 85 dollars and comes with the revo-shifter control. Also note that I do not peddle, or even have peddles at all. And I can kill any hill and still break 40! This motor has almost 3000 miles on it I think and I still get them numbers. The scooter pictured above was finished two weeks ago. Not counting the motor, which Ive used for several projects, all parts are new. Total cost was about $1050. I spent a fair amount on the brand new kick bike frame, and had the rear swing-arm fabed up by my buddy for a generous price. I gave him about 45$ an hour for his rate to meet my specs on the rear clip. Everything else was 100% 'off the shelf' parts. Shifters RULE! ;)
 
So how do you shift the manual jackshaft, use chain tool and then switch it or are they loose enough to slide over like a derailer?

but then you say this This tranny is about 85 dollars and comes with the revo-shifter control

I are lost. I dig it though, really like your setup minus the lack of a seat, planning to add one? Should make it so seat can fold forward some how and lock up i dont know if you stand sideways or straight if you stood straight a long seat post down th emiddle shouldnt be a bother. I rode straight the 2 times I rode a gas scooter, I can't leanif im goofy or regular standing like on skateboards lol
 
Oh wow, that is neat. So I could just mount that on my over rear mount same distance as motor sprocket is from wheel sprocket, and then reuse my current chain.


that sounds hot man, depending on which is input or output, that would also offset my chain perfect (I have the sprocket where it pushes the teeth outward instead of over the spokes cause motor sprocket sticks out) if the outside one is input and the inside one is output, that would work flawless!
 
If you need or MUST have the drive chain on the left side of the bike, you would need to use a sturmey archer S3X fixed hub which can drive in reverse though all gears.

Im not down with peddels so I'd drive it on the right side of the bike. But yes, the outer sprocket is input, and the one that is part of the hub-shell is output.
 
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