How to Build a Custom Chopper Frame

[Waylander]

On painting your tank, I'll be painting one myself once I strip it of the current paint and make a few other mods to the tank. I've got a compressor and a paint gun if you need those to use. They run on 110 rather than 220 so it has to go through a transformer but I got that covered. It'll be a while before I paint my tank but if you want to bring yours down on that day we can do them both at the same time.

[Spaz]

It would be easier for you to use that frame and just change it a bit. Stretch the top tube and down tube, widen the rear swingarm and such like that.

This plan sounds something like what I think I'll do. what kind of tools and information will I need to find?
I am no engeneer so I have no idea how exactly I would stretch any tubing and keep it strait.

Cheers

[White trash]

This plan sounds something like what I think I'll do. what kind of tools and information will I need to find?
I am no engeneer so I have no idea how exactly I would stretch any tubing and keep it strait.

Cheers

You don't "stretch" it as such, more like cutting it and welding a longer bit in here and there.

This is also going to effect the handling of the bike severly, and not for the better by any stretch of the imagination. You wanna read a book or three on chasis design to understand all the bits like "rake" and "Trail", and more importantly, the effects each change will make to your machine.

[Waylander]

You don't "stretch" it as such, more like cutting it and welding a longer bit in here and there.

This is also going to effect the handling of the bike severly, and not for the better by any stretch of the imagination. You wanna read a book or three on chasis design to understand all the bits like "rake" and "Trail", and more importantly, the effects each change will make to your machine.

This part he got right.

Yea do lots of reading up on this before you actually try it. There are a few books out there, (don't know if they are here cause I havn't seen them yet but I havn't really looked either) that will help you understand the basics of what you'll be doing before you get to the heavy stuff. These two here and here are good ones to start with.

They help explain some of the terms and a few of the technical bits so that you can understand the more advanced ones.

[TLDV8]

Anything is possible,but a basic knowledge of engineering/welding would not be enough to cut a frame (imho)...

It is easier to take it out than put it in..in days gone by it was not unusual to simply cut and remove a section of the top tube,then heat and bend the lower tubes to increase the rake,then reweld the top tube..

Here is a Ducati frame, rake was decreased by around 7 degree's by removing the stock steering head tube,recutting the frame tubes at the desired angle on a frame jig,then machining a new tube and welding it in

[hondacmx450]

if you want the number of a person in auckland to talk to pm me i have a mate of mine that has just done what you want to do but he did it to my old drag bike now it is a drag choper and nice to

[Waylander]

Some late night reading...

These are mostly for if you want to build a new frame from fresh materials but you might find a tid-bit or two that could help you out.


http://64.172.168.34/neatstuff/

http://64.172.168.34/neatstuff/old_s...pper_frame.htm

http://garagechoppers.com/archives-Chopperfreak.shtml

http://garagechoppers.com/archives/000675.shtml

http://garagechoppers.com/archives/000698.shtml

[Waylander]

Just found something that might help you more. Explains how to do the welding of new pipe into the exhisting frame to "stretch" it out and a few other things.

http://garagechoppers.com/archives/000502.shtml

And the whole "rake" and "trail" thing.
http://garagechoppers.com/archives/000476.shtml

[clint640]

If you are going to build or modify a frame:

TALK TO THE CERTIFIER FIRST!

There will be someone around that cert's bikes, talk to them before you do anything, tell them what your plan is in detail, ask them exactly what they want to see when you turn up with the finished bike. Write it down.
The cert guys I've had dealings with when modding my 4x4 have been good blokes who are happy to take the time to help out. If you keep them in the loop from the start the inspection will be a mere formality.

If you are 'no engineer' you might want to ask yourself is it worth putting over $2k (cos that's wot it'll cost, the cert alone is $400) into a GN250, but I like a crazy plan so good luck.

Cheers
Clint

[RedRocks]

Mate don't try this at home! Chances are you'll chop ya fingers off or have a few ACC moments along the way. Also your welding needs to certified, then the bike needs to meet LTSA requirements & get certified too. What a nightmare!!!

If your serious about building a bike, let me know. I can build you a tank and fenders using mallets, sandbags and an english wheel in about 5-7 days, all handbuilt, one of a kind....