Building my first mini bike from scrach!

#1
First, a bit of a back story. When I was 10 years old, I went to my buddys birthday party (not many people, about 10 people were there) and after cake his dad brought out brand new mini bike! (Believe it was a baja doodle bug or a manco streaker, cant remember, but it was red and looked cool!) I remember I was begging my mother for one.
5 years later here I am, got my own welder, and building my dream mini bike from scrach!
I have a limited budget, 120$ (because that's how much I sold my pedal bike for) I've spend 60$ for the frame, forks and wheels.
I'll update you on how this goes, wish me luck!
Heres some pictures (got home late, managed to get half the frame done)
 

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#6
That does not look safe.
It's not, probably because I just taced it together. I'll be adding some supports later. Plus who needs safety, I'm taking a crap engine that has one if the weakest rods in history and bypassing the govener.
So safety Is like a 5th on my list
 
#9
Please have plenty of air circulation while welding galvanized steel. Drink a great deal of milk 8 hours
before and 8 hours after, will help your body get rid of the zinc oxide, in your blood stream. The zinc
oxide will cause flu like symptoms. The old timer welders taught me about drinking milk to protect
oneself. I believe it is true.
 
#10
Please have plenty of air circulation while welding galvanized steel. Drink a great deal of milk 8 hours
before and 8 hours after, will help your body get rid of the zinc oxide, in your blood stream. The zinc
oxide will cause flu like symptoms. The old timer welders taught me about drinking milk to protect
oneself. I believe it is true.
ill try it out, see if it works lol.
i weld outside whenever its galvenised (or painted)
i would be 100x eaiser if i got a pipe bender, but im hella cheap
 
#11
Update!
I forgot you update you guys, sorry about that lol
Ive made the seat, and started on the front forks, there a bit short (ran out of pipe lol)
I'm waiting on the carb and sprocket, they should be here next week.
But heres some pics!
 

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#12
Update!!
Finished the front forks (found some pipe under the work bench yay!), fabed up some rear deopouts, and welded up the engine plate (will probably be replacing it I have some 3/16 Steel that's better suited for the engine plate)
But Heres some pics!
 

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#13
To weld on galvanized take the grinder and remove the galvanization about an inch back from the area to be welded. Not only is it safer, the welds will flow in and not look like cat poop sitting on the surface. There are many issues you are up against to make this a functioning bike, but two of the largest are brakes and how to mount the sprocket to the rear wheel. My guess is that you are leaning towards Flintstone brakes. The major issue is how are you going to connect the rear sprocket to the wheel.
 
#14
To weld on galvanized take the grinder and remove the galvanization about an inch back from the area to be welded. Not only is it safer, the welds will flow in and not look like cat poop sitting on the surface. There are many issues you are up against to make this a functioning bike, but two of the largest are brakes and how to mount the sprocket to the rear wheel. My guess is that you are leaning towards Flintstone brakes. The major issue is how are you going to connect the rear sprocket to the wheel.
I was planning on welding something (washers?) To space out the sprocket then weld on a flat plate. Drill and tap. And make it a hub.

For brakes, well flintstone brakes are free so lol.
But i will probably make my own brake (4" brake band on the clutch, lots of yt videos on how to do this)
Thanks for the welding tip! (But its probably to late now, im planning on just clear coating it, looks really good to me)
 
#15
As a builder of many scratch built progess , I'm impressed with your work so far

As for attaching the rear sprocket , I have used threaded coupler nuts
Run bolts thru the rim from one side and thru the sprocket from the other
Good luck
 
#16
As a builder of many scratch built progess , I'm impressed with your work so far

As for attaching the rear sprocket , I have used threaded coupler nuts
Run bolts thru the rim from one side and thru the sprocket from the other
Good luck
Thank you!
I am just welding the sprocked directly on to the hub (not the best, but itll be fine)
Im using a motorised bike sprocket as those are offset. And it will clear the chain.
Im lazy so this project is getting delade by a bit lol.
(Also need to weld a engine plate, this one in the pic is too thin)
 

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jeep2003

Well-Known Member
#17
Cool everybodys got to start somewhere. You can actually get pretty nice bends by pie cutting the inside. You were smart to make the wheel nice and close to the engine a short chain doesnt fall off as easy. But you have to take into consideration the wheelie factor with the seat position.
 
#18
Cool everybodys got to start somewhere. You can actually get pretty nice bends by pie cutting the inside. You were smart to make the wheel nice and close to the engine a short chain doesnt fall off as easy. But you have to take into consideration the wheelie factor with the seat position.
thank you!

its a fun ride, and very wheelie able!
(me and my buddies bet on how long we can hold it. are best was 10 seconds)
i was planning on adding a wheelie bar but. live and learn (the headtube needs some reinforcing, it bent when we messed around with it.
 

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