How to Build a Custom Chopper Frame

**Spaz** · 3rd August 2005, 22:11

Well I've had a little bad luck with my GN so I was looking at giving her a new lease of life.
After watching Monster Garage evil plans started sprouting in my head and I went in search of information on home building choppers out of every day house hold items. Thanks to the wonder that is google I found this: http://www.vabiker.net/ads/chopper-frame.html oh joy!
More research informed me that I would need to construct a jig in order to construct the frame strait and true. I think all up the information will cost me about US$100 and then I would need to get materials, stuff up a few times, get more materials and then viola!
I'd also need to take a crash course in welding, find a mandrel, a new tank and someone to paint it.
Before embarking on that, is there anyone here who can tell me how to do it right and save me fluffing about in the 'encyclopaedia of American style'?

ALL input welcome (no matter what it is),
Cheers.

**Ixion** · 3rd August 2005, 22:20

Planning to ride it on the road? If so it will need low volume certification, and you'll need more than a crash course in welding to produce a frame from Reynolds tubing. Unless you use heavy gauge tubing and braze it the old way. Easier to do, but it would be heavy, and you will not be able to get the gusset forgings.

A very ambitious project for a GN250. Not wishing to rain on anyones parade, but maybe best to check things out fully before making any commitments.

What was the bad luck with the GN ?

**Hitcher** · 3rd August 2005, 22:30

Are you serious about chopperising a GN250?

**Spaz** · 3rd August 2005, 22:31

Guy ran into the back end of me while I was sitting at the lights, it's rideable but there is something wrong in the frame.
I thought with all the hype that is going around this style I would be able to get something out of it if I did it well (skill and $). GN's are really slack when it comes to power so I would need to do it with weight in mind.
Cheers

**Spaz** · 3rd August 2005, 22:34

Originally Posted by Hitcher

Are you serious about chopperising a GN250?

I need a project.
Much like the apple was to Newton, a Toyota Corona is to me.

**Waylander** · 3rd August 2005, 22:44

What exactly is wrong with the GN frame? 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. Would make it much easier on you down the line when it came to registering if the frame already has VIN# and such.

Looking at doing one myself out of my CMX once everyone in my family and a few friends use it to get thier lisences on.

**Spaz** · 3rd August 2005, 22:52

Originally Posted by Waylander

What exactly is wrong with the GN frame? 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. Would make it much easier on you down the line when it came to registering if the frame already has VIN# and such.

Hmm, I'm really not sure what's wrong with it, whatever it is it's not shocking news. I thought getting rid of it and making a new frame would fix the problem but that sounds bloody good to and it would get me around the VINing problems. I might find out what the problem is when the bike is compleatly apart
Cheers

**Waylander** · 3rd August 2005, 23:04

Originally Posted by Spaz

Hmm, I'm really not sure what's wrong with it, whatever it is it's not shocking news. I thought getting rid of it and making a new frame would fix the problem but that sounds bloody good to and it would get me around the VINing problems. I might find out what the problem is when the bike is compleatly apart
Cheers

Yea find out when it's appart. If it is just the swing arm then sweet. Exspecially if you want to put a bigger tire on the back. You would have to replace or heavily modify it anyway.

Keep in mind though that GN motor wont be able to turn anything too fat so I wouldn't go anything above maybe a 170 or 180.

**Odin** · 4th August 2005, 07:33

It sounds great and all the luck in the world to you. sometimes its great just jumping ind and then finding out if one really CAN swim or ...
Just be sure to think it trough first, if you build a new frame you will most likely also need to get a new wirering harness and things like that.
As to painting you should be able to do that your self. That would be one of the easier parts of the project i'd say. Unless you want a real custom job with flames and the like.

But keep us opdated please

**FzerozeroT** · 4th August 2005, 09:15

for the price of the plans and to build your own jig you could probably pay someone to build it for you

**White trash** · 4th August 2005, 09:32

Hey Spaz, cool idea man. But don't junk the original GN frame. The bit that;s buggered sounds like the sub frame if you were hit from behind. That's easy enough fixed or replaced.

Keep the main frame as it already lines up your steering head and swingarm mounts nice and straight. If you strip the frame right back, a decent engineer will be able to "strecth" and "rake" front end and build a diffeerent subframe to suit your new "Low rider".

Wouldn't be my personal choice of chop' but each to their own, go hard.

**Odin** · 4th August 2005, 09:46

Originally Posted by FzerozeroT

for the price of the plans and to build your own jig you could probably pay someone to build it for you

And how much fun would that be ?

I say go for it, if nothing else it'll give you something to do and develop some skills and hopefully show some caracter when its all finished

**ezinnz** · 4th August 2005, 19:56

If you go ahead and modify the frame it will need inspection for certification as previously mentioned. If you take it to an engineer to do the job, make sure he has his welding ticket because you'll need to prove he is a certified welder to do structural work on your frame. If you can't produce this, the certifier will most likely ask you to have the welds x-rayed for cracks. This is specialised and expensive.

You could stick to your plan and learn to weld and have some fun. That's what it's all about. Maybe not ever get it certified for road use. I'm a fairly experienced welder but I still wasn't keen to try and build my own frame. I had a guy with a lot of experience build an 'open space' frame for me and then I put all the engine mounts, tabs, brackets etc on it to suit.

A failing frame at any speed will hurt. You can't be too careful with this part of your build.

Hope this helps.