OK, 125 shifter karts are respected as scary fast in autox, we have seen videos of them on the street doing crazy fast things. But, a 125cc motorcycle is hardly sufficient to move a 15yo boy. Would somebody explain to me how the laws of physics seem to alter when that itty bitty motor gets put on a cart that it becomes a beast? Please chime in as I have have bad ideas about a 250cc kart.
cwh wrote: But, a 125cc motorcycle is hardly sufficient to move a 15yo boy.
2 stroke + gearing - weight = fast
The 250 carts Iv'e seen are scary fast. 400 and above carts are stupid.... You just can't put that much power down on that small of a tire.
My boss had a 2 stroke TAG kart(single speed) 100cc... He said it was plenty fast, but he bought a shifter 125. With the 100cc he says he was bump drafting at 110mph on the back stretch at road atlanta...
Also - I'd hate to see your 15 year old. I'm not small and I can have plenty of fun on a 125 bike.
http://www.youtube.com/watch?v=VAfVYGmaw_o <--- that old tired kart makes 30hp.. Same hp as a vw bug 1:10 the weight.
Lets see, I still have my IKS Maxi enduro cart chassis sitting in a friends garage. I have a 500cc Ninja that my wife doesnt want me to ride. 1+1= insanity 
By the way I am going to spectate at my first Auto Cross tomorrow 
http://www.premiumposts.com/250cc-shifter-karts-go-cart-on-steroids/
These 250cc shifter karts can hit 60mph in 3 seconds flat and whip around a full size race track at speeds in exess of 125 mph. In fact, these 250cc Shifter carts have been clocked at the old A1 ring in Austria going over 180mph! Also… don’t worry about slowing down much in the corners because these shifter karts can hold 3.0 lateral g’s of cornering and braking force!
do you really want to go THAT fast with your ass only an inch or 2 off the ground?
ive heard of 125cc shifters running about 100mph on longer tracks before. You also forget the cornering speeds they can hold.
porksboy- find out if they will let you run that monster if you build it. the thing that would keep me from doing it would be that you couldnt run it anywhere.
Yeah 125cc bikes aren't that slow...
And it's not going that fast 2" off the ground that scares me...it's the fact that there's only 1 layer of material between my ass and the ground (the seat itself.) I like to have at least two when sitting in a vehicle. If there was some sheet metal under the seat I wouldn't have a problem.
At this point in my long and adventurous life I have a list of unfulfilled fantasies- like being a bar bouncer, etc. Guess I should move the 250 cart idea into that list. I would like this life to go a bit farther.
Those things are nuts. First time I saw one on an autocross course, I thought I was watching a Road Runner cartoon or something. There is NO way anything can accelerate that quickly, brake that hard, or corner beyond the realm of physics, but there it was..
The guy driving it told me he was shifting about 40 times per run...... it was a 60 second course. Unbelievable, but apparently true.
Awesome.
I apoogize if this is obvious, but don't compare a 125cc four-stroke to a 125cc two-stroke. Since the two-stroke has twice the power strokes, it will make (very roughly) twice the power.
Recently I let my brother drive my shifter kart. It's a TonyKart with a Kawasaki YZ125 125cc two-stroke with a six-speed transmission. "Back in the day" it dyno'ed at 43 HP. My brother said it was so fast he was terrified on every straightaway. Every shift slapped his head back, even the 5-6 shift. He said comparisons are nonsense, as there simply is NOTHING that compares to a 125cc shifter.
On the long course at PKRA, I run around 51 seconds a lap with 24 shifts per lap. Things happen fast on a shifter!
The Bondurant School in Phoenix also has a shifter kart school. They made a little video comparing a C5 Corvette Z06 to a 125cc shifter. Guess what, the kart spanked the Corvette.
By the way, that race video of the "250cc shifters" are neither 250cc nor are they shifters. ON the straightaways, I pass a 125cc single-speed kart about when I shift from fourth gear to fifth, and I've still got sixth to go.
Shifters rock!
David
hell, 80cc shifters are damn fast even for adults.
heck.. non-shifter carts are a LOT of fun on a small track.
Back in the 80's we ran the enduro with a 100cc piston port 2 stroke Yamaha engine with a single speed and a slipper pipe on the exhaust. When at Taledega I was running an open practice session. A speed gun was set up at the end of the front straight just before you dove into the infield. Comming off the high banking I was clocked at 118MPH. I thought "thats pretty good" then a 250 shifter cart went by me like I was sitting still. It realy took the lead out of my pencil.
I really wish there was a asphalt sprint track near me. I would be all over a kart if there was.
From my research it would be a 4 hour drive to run for me and it really keeps me from wanting to do it. (unless there's something I'm missing near western Maryland.)
Western Maryland? Would they allow karts to run Summit Point? More interesting to watch than Formula V or 440.
summit point is about 2-3hours away, so i guess its a bit of an option. That is still a bit of a drive though. I am planning on going to hyperfest this year so ill have to see what kind of drive it is.
I know there are lots of people who drive much further for a motorsports fix, I may be too used to being 15min from the autocross site and 30min or less from the hillclimb site.
to the OP... no one has mentioned yet why a 125cc kart is SO much badder than 125cc Dirtbike. (oh btw engine size doesnt matter or 4 stroke vs 2 stroke...it's about horsepower ....and Horsepowerwise...a kart of equal horsepower will always KILL the stats of a bike of equal HP)
here's Why..... CG (center of gravity) a Bike is Hugely top heavy compared to a kart...actually any vehicle is top heavy compared to a kart...THAT's why karts are such performers !!! (compared to anything)...
turning is all about changing direction ...so for the benefit of explanation..always imagine a u-turn... I wonder how well a double decker bus would do ? you see what Im getting at ?
also traction...a kart has many times the Rubber contact patch of a motorcycle. I've raced them all Road bikes , dirt bikes, shifterkart, autocross, circle track stock cars and so on...
You guys wanna do better at auto-X ?...Lower your CG as much as possible and condense the weight of your car to the center as much as possible...your car WILL turn better...simple as that .
have Fun ! ;)
HAHAHA... this just has to make you smile... http://www.youtube.com/watch?v=qv-2Gi7l72k&feature=related
A kart is considerably lighter than a motorcycle. Road legal 125s weigh 250+ lbs, an ICC shifter is going to be under 200.
Even a 5HP Kart can get you some pretty serious speed. Shifter karts are lat out Captain Insano. I want one...
http://www.youtube.com/watch?v=g6H2HvsiTjo&feature=related
just unreal... & that's on 20yr old tire technology, imagine the cornering now!?
http://www.youtube.com/watch?v=bf3cJRkeEqE&feature=related
Looks easy to drive beyond one's ablility.
Apexcarver wrote: From my research it would be a 4 hour drive to run for me and it really keeps me from wanting to do it. (unless there's something I'm missing near western Maryland.)
Summit Point now has its own kart racing league.
How about non-shifter carts? What will one of those cost?
Shifter karts are the most fun vehicles to drive ever! I haved both enduro(laydown) 125cc and sprint 125cc shifters. They are so fast as has been mentioned earlier due to gearing, traction, and the super low center of gravity, and mostly for the laydowns with full body work, and under tray, they have very little frontal area for aero drag. Back in 94' when I raced Daytona, we run the 24 hour couse minus the bus stop chicane, my lap times were 2:03's and top speed was 131mph on the back straight. The 250 singles(cr250 etc..) were runnning 151mph and now the 250 twins(Honda RS250) will run high 170's.
For all the info you ever need check out World Karting Association for tracks, classes etc. Also look around ekartingnews.com for classifieds, events and more.
They do race real karts at Summit Point with what is arguably the best club in the country Woodbridge Kart Club. www.woodbridgekartclub.com
Paul For
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