Easiest way to keep a minibike stable at speed?

#1
Running about 46 now and it gets hairy. stretching it and adjusting the rake and/or trail is the fancy way... Any other "tips". I don't have the time or tooling to stretch the bike correctly. ANy short cuts? Also adjusting the rake seems risky if done improperly with the wrong tooling/jigs etc. I do have a welder and I can weld decently. But I don't want to trash the geometry of the bike if possible. Any bolt on forks that kick the front wheel out a bit? Other tips/tricks?

Thanks!
 
#2
My ct70 clone got an adjustable hydraulic steering damper to eliminate the dreaded death wobble that almost left me with a bad case of road rash. A much longer wheelbase and more rake/trail is the only real solution to your problem.
 
#6
Its an untouched doodle bug frame. Nothing fancy. But it is pretty new. What if I extended the front wheel FWD like so 5-6" or so? Leaving the factory forks untouched for the most part.



rake1.JPG
 
#8
I don't honestly care if it turns much at all. It's a straight line "drag bike" toy to compete with buds. How far would be "ideal" if there is such a thing?
 
#10
My drag bike used to be a little bit squirrelly, but things that helped was lowering the bike so it is like 2” off the ground.
This entailed chopping down the forks and rewelding them, and relocating the rear bearing hangers.
Also my bike has bronze bushings in the head tube, so I bought some oil impregnated bronze material and had new bushings machined. That tightened things up real good. Also added some weight to the bike, about 25lbs worth of junior dragster clutch, jackshaft, engine mount and crank bracing.
All of those things made it run real smooth, I don’t really dig the steering dampeners.
To me, if you need a dampener then there is a problem and I would rather fix the problem than try to cover it up with a dampener.
IMHO, ymmv, etc
 
#13
Here's my drag set up MANCO THUNDERBIRD..WITH THE CURRENT MODS ON THR ENGINE WE HAD IT CLOCKED AT AROUND 70 WITH MUCH MORE THROTTLE TO GO...IT GETS SKETCHY AT ABOUT 50 AND IT WHEELIES IF YU DON'T GRADUALLY ACCELERATE DECENTLY SLOW...WITH THE NEW 10 INCH MODULAR WHEELS AND OFFSET TIRES THE CENTER OF GRAVITY IS OFF...TO THE AFFECT IT FEELS AS THO THE FRONT WHEEL IS LITERALLY GRAZING THE GROUND...I WANT TO STRETCH IT MAYBE 3 INCHES TO HAVE THE BACK WHEEL FARTHER OUT TO KEEP THAT FRONT WHEEL ON THE GROUND..ANY IDEAS? THE STICKER BOMBED ONE IS THE DRAG BIKE THAT IM CONSIDERING STRETCHING...THE OTHER ONE IS SAME MAKE AND MODEL BUT NO WHERE AS FAST AS THE DRAG.. IMG_20191024_031612054.jpg IMG950611.jpg
 

Cuda54

Active Member
#15
Have you checked the bearing in the neck of the bike? It really does not take much flex to make the front end move around. Even the rear wheel bearing can make it a little wild at speed. Any flex in the frame can do the same as a loose bearing. And if you move around on the seat and change the center of gravity can move the bike all over the road. Take the chain off and put it on a treadmill run it as fast as it can go with you sitting on it. With your feet on the outer edges to see how stable it is. Lean it back and forth to se it want to move around. If the forts are bent in any way it can make it wonder around. Has the frame ever been bent it any way? The way the bike and wheels are balanced can add up as speed increases too.
 

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