43 Mph Huffy Cranbrook!

Hi Everyone!

I build a 66cc grubee motorized huffy and I did a couple of upgrades now I get 43 mph.

The handling is not bad but a those speed I would like to get more stability.
Any advices?

I did the folowing mods:
Head shaving
correcting the transfer ports
porting
port matching
jaguar torque pipe
homemade boost botle
32 tooth sprocket

 

[KCvale]

Very Cool man, good job mounting a disc to a regular wheel!

How did you mount the caliper?

 

[LewiSStyle]

Thanks, I'm very happy of the result.

I mounted on the stock fork with 1/4 bolts and a homemade steel bracket

 

[LewiSStyle]

Hi everyone!

My motorized bicycle is now a joy to ride with the disc brake but I am still searching to obtain more stability.

I did uprade the thins tubes with some heavy thornproof tubes to incrase the weight of the wheels, it helped but the handling is twichy like any bicycle...

I would like to have motorcycle like handling, a smooth steering. Is this possible?

Thanks

 

[Slogger]

Changing the geometry of the front end would fix it but it isn't easy or cheap. Some of the springer forks space the wheel farther forward, and there are those odd suspension mods using pivoting arms at the bottom of the fork with springs anchored on the front of the legs. If you go this way though, your brake setup would have to be re-done. Raking the gooseneck would mean welding or tigging (aluminum?) but the brakes you've built would work.
A steering damper might be easier and fix the jitters for ya.
That's a nice bike you're building, the brakes are really nice.

 

[LewiSStyle]

So if I understood correctly, a fork that put the wheel father foward will make the handling smoother?

then why a motorcycle fork isn't curved foward like a bicycle one?

Thanks, I did spend a lot of time on it

 

[Slogger]

It would make the steering slower. The longer wheelbase will make it a little more stable at speed, also. This is only if it is a good quality fork without any wobbliness.

Motorcycles use the rake of the gooseneck to set the geometry along with other minor tricks like having the axle bosses on the front side of the fork sliders rather than centered on them. A curved fork wouldn't allow the typical suspension on a motorcycle work.

 

[LewiSStyle]

I did a little search about bicycle and motorcycle forks and it seems that increasing the curve (offset) of the fork will reduce the trail length and it will make the handlebars twichier (not good)

So a strait fork will in theory increase the trail lenght and it will make the handlebars harder to turn.

Do this make sence?

 

[Slogger]

I'm unable to explain it any differently than I did up above. Lengthen the wheelbase = more stability.
Kick the front wheel out in front of the fork, you'll have heavier, slower steering.
I wouldn't re-bend any fork tubes on my bike. I'm too old and heavy to risk it.

 

[LewiSStyle]

I understand your explaination about the lenghtening of the wheelbase.
However from what I learn, if you do it by increasing the curve of the fork it will mess the trail length, I think that we need to do some experimentation on that...

Take a look a that, it explains the effects of the trail length: http://bikearama.com/theory/motorcycle-rake-trail-explained/

 

[RumblingV8]

I'd say a fork with suspension might help. On my 2nd build (also a cranbrook) I'm still in break in but having ridden at moderate speeds going from stock fork to springer fork (which also gave slightly longer wheelbase) is more stable. Makes me wish i went that direction with my first bike. I believe depending on the fork you can get them with disc brake brackets either built in or an adapter, which in your case you can competently make yourself so you could easily keep your front brake setup. Or if you go with a regular mountain bike suspension fork, it makes disc brakes easy too. Depends on the look you want, i guess. I enjoy the simplicity of the springer.