Two Stroke Motocross

Two Stroke Motocross Forum => Open Forum => Topic started by: JETZcorp on November 28, 2010, 06:43:18 AM

Title: I have... a Dream!
Post by: JETZcorp on November 28, 2010, 06:43:18 AM
Someday, some way, I will create this masterpiece.

The basic idea, is to make the ultimate homemade, one-man, off-road kart/buggy or whatever you want to call it.  Now obviously, there are karts you can buy that use snowmobile or sportbike motors, complete with ECUs, limited-slip differentials, etc. and honestly there's no way I'm going to make something to compete with that.  However, what I can set out to do, is eclipse everyone else's home-built efforts, simply by thinking big.  As in, 490cc big.

Let's start from front-to-back.  The front wheels (and indeed, all the wheels) I think should be 12-inch rims, basically like you'd have on the back end of a 65cc KTM or something.  I might use disks or drums just depending on what I can get my hands on, disks obviously would work better, but then drums never develop fluid leaks (this was a problem with the front disk on my dad's '86 Maico).  Anyway, the front wheels are going to have independent suspension, and I don't see why a nice pair of piggyback Ohlins like you'd get on a late '70s Husky wouldn't do just fine in that role.  They would be configured to "lay down" as they compress, just like in a bike, except they lay down laterally instead of longitudinally.I'm looking for at least six inches of travel, and hoping for more like eight to ten.

Steering is something I haven't entirely worked out yet, simply because I can't honestly claim to know how that even works, but hopefully by the time I get an engineering degree and start work on this project, I'd have that figured out.  But, obviously there's not going to be any power steering or any of that nonsense, I want this whole thing to as simple as possible, so anything that goes wrong can be fixed with a brick, and a piece of string (to steal a line from Top Gear).  Throttle, brake, and clutch will be controlled with foot pedals, just like in a car.  The throttle and clutch pedals will be simply hooked up with cables to the engine, which sits behind the seat.  The brakes... well I'll figure that out when I get there.  The seat itself will have to be one of those very supportive seats that holds you entirely in-place, with a harness like you'd get in a real performance car.  Doesn't need to be a big name-brand like a Sparco or Recaro, just something that works well and doesn't cost $1,000.  Gear shifting is simplicity itself, the sequential transmission from the 490 Maico will still be used, and a hand-operated lever will be hooked up with linkage to the shaft that's normally connected to the foot-shifter on the bike.  Push forward on the lever to down-shift, pull back to up-shift.

That brings us to the engine.  Ah yes, the good old 490 Maico engine we all know and love so much.  Of course there's some variability in this, depending on what I can find - the main thing is that it be a big-bore Maico engine, roughly between the years of 1978-1983, just so long as it's big and air-cooled.  This engine will simply be pulled right out of the bike, and placed into the kart directly behind the engine, facing forward, and probably tilted a bit so that the cylinder axis is vertical (this reduces the amount of space it will take up).  To start the thing, I plan on simply standing next to the kart and kicking it over, like a boss.  This will probably mean putting the compression-release lever on a frame rail nearby for easy access.  Depending on how the ergonomics work out (for example, if the kickstarter interferes with the rear wheel) then I may have to do some dancing around to get it started, I really would rather not deal with a battery.  Of course the gas tank will also have to be located above the engine, because I don't want to mess around with a fuel pump, so that will probably just find its way being mounted on the frame above the engine.  I plan on using the stock pipe.

The rear wheels are (obviously) going to be driven by the engine.  It will be hooked up via a chain just like normal (albeit shorter), but instead of going to the axle itself, it will connect with a differential, taking the place of the bevel gears normally found on rear diffs.  The torque thus split, the power is then transmitted to the wheels separately, which are mounted on independent suspension just like the fronts, again probably on Ohlins or some other kind of shocks intended for dual-shock long-travel bikes.  Wheelbase is 6.75' in my preliminary sketch, hopefully I'll be able to work that down a bit, because I'd like to be able to get it in the bed of a truck, provided the tailgate gets left down, and the truck I intend to get has a 6.5' bed (not counting the tailgate).  It's still a little too long because of overhang, but I think I could probably find some inches to trim away.  Width is not really an issue, somewhere around three feet, maybe a little more.

So, any questions or comments?  The intent for this thing is to be the ultimate dirt/gravel road terror.  I'd like to use this thing for blasting down fire-roads basically like a rally car, except it can be much more easily transported and would cost a lot less than buying an Evo and thrashing it around in the middle of nowhere.  Plus I think performance would be better than the Evo as well given the power and weight we're dealing with, I don't see this creation being over 500lbs.  I do anticipate the front wheels might have a tendency to throw rocks at me, particularly during over- or under-steer, so the design (such as it is so far) includes some aluminum sheet metal, which will either be painted red with a big yellow slash (imitating a '77 Maico) or simply left as bare aluminum with a giant Maico logo on it, like the early '76-and-earlier aluminum coffin tank Maicos.
Title: Re: I have... a Dream!
Post by: SachsGS on November 28, 2010, 09:07:30 AM
Why not start with an old fashioned VW bug powered "rail" dune buggy? A friend had one that was about 100hp and 1800cc. We climbed a steep boulder strewn creek bed that you couldn't climb with a trials bike and out in the open I was able to reel in a guy on a KX250.Plus it had reverse.

What I've seen people do as well is retro fit a Honda Odysse with a KX250 motor or something similar. 
Title: Re: I have... a Dream!
Post by: JETZcorp on November 28, 2010, 07:21:12 PM
A lot of what appeals to me about this project is that I'd be making the thing.  It's more satisfying to say, "Look what I made" than "Look what I bought."  I may well end up scavenging a lot of components from existing models, but in the end I want this to be my own, one-of-a-kind creation.
Title: Re: I have... a Dream!
Post by: SachsGS on November 28, 2010, 09:30:10 PM
I've built my own frankenstein specials as well as having worked in the high tech sector and developed various prototype machinery and, what I am trying to say is never underestimate the magnitude of what you are proposing. I've always doubled capital requirements and multiplied estimated man hours by at least a factor of four. It takes a lot of cash and a huge amount of labor hours to get anything new designed and built.I have a machine shop at home and it would take a lathe,milling machine,pipe bender,chop saw,horizontal band saw,200 amp (min.) MIG welder plus many other tools to be able to properly build such a project. Having AutoCad at your disposal would help as well.You must also possess all the skill sets necessary to move the project thru. each phase as well.

 Now I am not trying to "take the wind out of your sails" but rather,I suggest tackling something a little less daunting initially (120 silencer anyone? ;)). One really should walk before running.

Western society must retain the ability to develop and build state of the art machinery, our standard of living depends on it.So dream big and take the necessary steps to get there. :D

Title: Re: I have... a Dream!
Post by: factoryX on November 28, 2010, 10:34:22 PM
I like this idea. kind of like a pissed off low profile fl400/fl350 but built properly. My idea was to do almost the same thing and use polaris outlaw Suspension.
Title: Re: I have... a Dream!
Post by: JETZcorp on November 28, 2010, 11:21:09 PM
Don't forget, I'm not planning on starting this tomorrow, this is something for way WAY down the road after I've been a mechanical engineer for a long period of time, and then finishing the thing five or ten years later down the line.  I have no delusions that I'll be driving off-road in the next riding season with this little thing.  When it does come time to finalize the design, I fully intend to do it properly with Inventor or SolidWorks or something of that nature, and because I don't want to be killed I plan on doing some good old FEA to minimize the WAGs. ;)
Title: Re: I have... a Dream!
Post by: SachsGS on November 29, 2010, 08:38:40 AM
I'd watch those time estimates. Before you know it your life will be defined by mortgage payments,diapers,squalling brats and a mother in law that makes Jack the Ripper seem like not such a bad guy.

Around 2002 there was an American company called Storm that imported a few badge engineered Maicos and was developing a Maico 500 powered ATV.Not sure how far they got with that idea.If I were to embark on a project of this nature I would hunt down a Hewa Maico sidecar motor.It would have the correct torque characteristics and gearbox ratios (and cooling system).
Title: Re: I have... a Dream!
Post by: factoryX on November 29, 2010, 10:08:21 AM
cough Zabel 700 cough
Title: Re: I have... a Dream!
Post by: TMKIWI on November 29, 2010, 10:58:23 AM

Someday, some way, I will create this masterpiece.

  simply by thinking big.  As in, 490cc big.

Thats not big.
I have an old Johnson 235hp 2.6L outboard block sitting up stairs and my staff have been thinking of putting THAT in a buggy.
We just need to make up some kind of exhaust manifold and close of the cooling system.
If you are keen on a drag race jetz let me know. :P
Title: Re: I have... a Dream!
Post by: opfermanmotors on November 29, 2010, 12:44:32 PM
A few years back I developed a dune buggy to ride at Sand Lake.  I bought an old VW frame minus the motor and I created a roll cage out of PVC pipe.  Instead of an engine I decided to go propeller designed, however airplane engines or creating a propeller was a lot of hard work.  What I did instead was get a few boards and make an X, then I nailed an old motorcycle inner tube to the back of the board and to the back of the car.  All you need to do then is wind up the propeller and let it go.  I took it to Bonneville and we were clocked at about 0.   

Title: Re: I have... a Dream!
Post by: JETZcorp on November 29, 2010, 06:09:39 PM
Kiwi, if you're up for a drag race, I'll mount a 392 Hemi in my kart and we'll see how it goes.

As for the mother-in-law and squalling brats, I've already got that covered by being an antisocial bastard IRL.  That's part of my Long-Term Horsepower Maximization Strategy (LTHPMS (pronounced Luh-THUMPS)).
Title: Re: I have... a Dream!
Post by: TMKIWI on November 29, 2010, 09:30:30 PM
Kiwi, if you're up for a drag race, I'll mount a 392 Hemi in my kart and we'll see how it goes.

I think you may have a weight problem with that Hemi. ;)
Title: Re: I have... a Dream!
Post by: JETZcorp on November 29, 2010, 11:05:35 PM
What you call weight, I call grip. :P