building custom chopper frame

[Shox Dr]

I've cut up a few jap bikes and their frames can be scarily thin from the factory.

I've two slabside frames here, the welding inside of the head stock gusset is frankly scary.

 

[Gwil]

I've two slabside frames here, the welding inside of the head stock gusset is frankly scary.

Did they break though? Had one myself- 1260 kit and nitrous. Rode it like I stole it (I was young then and exceedingly foolish.....) and it didn't break either.

 

[lchris21]

to the OP. I'd suggest MIG if your fit up is questionable? TIG is not very forgiving with inaccurate gaps, it could get messy very quickly. Do your research on materials, jigs,geometry, fixtures etc, and grab some steel and dive in......
Don't be afraid to have a go, you'll make mistakes, but you'll hopefully learn by it??
I just finished my first ever custom bike, chopped and changed a few things, added some bits and took some away. It turned out ok in the end. Made a few mistakes on the way, and had some good pointers during the build. I'll take the lessons learned, forwards onto the next one.
Get a build thread started on here or a dedicated bike forum, and post up some progress you'll soon get some feedback if anything obvious is going wrong.
Best of luck and keep us posted....
PS I was in my local paintshop last week looking at a "professional" commercially available frame that was about to be painted............the welding was rubbish, and some of the mounting lugs looked well crooked...

 

[dobbslc]

A quote from the above post by Ichris21 " it turned out ok in the end" !!!

Bloody understatement of the century!
To the OP have a look at the build thread by Ichris21, the bike and workmanship is stunning.
I'm making a cafe racer myself with no real welding skills as such but I'm having a go!
I've got an old tig machine that I'm practicing with so I can make a seat sub frame and modify the tank.
Not sure I'd go with making a frame from scratch myself just yet though...

 

[julianthegypsy]

A quote from the above post by Ichris21 " it turned out ok in the end" !!!

Bloody understatement of the century!
To the OP have a look at the build thread by Ichris21, the bike and workmanship is stunning.
I'm making a cafe racer myself with no real welding skills as such but I'm having a go!
I've got an old tig machine that I'm practicing with so I can make a seat sub frame and modify the tank.
Not sure I'd go with making a frame from scratch myself just yet though...

You beat me to it! "Turned out ok in the end?" It's an absolute stunner!

 

[selectedgrub]

Besides whats the point of creating your own bike and not riding it! And yes there are many abortions about under the chopper name, but there is also some fantastic ones, mr select grub for example has a very interesting bike project.

Um thanks, I think

 

[addjunkie]

To the man on about the bonneville stream liners go to britchopper forum, there are a few bonneville build threads on there, featuring a few of the guys on the bbc programe. Good reading. Clever folk.

 

[ronan]

You have to have a look at this

http://www.crossbreedcycles.net/index.html

 

[AdrianH]

To the man on about the bonneville stream liners go to britchopper forum, there are a few bonneville build threads on there, featuring a few of the guys on the bbc programe. Good reading. Clever folk.

One of them was on Locostbuilders under Flak Monkey I think was his user name, (David Dickerson?).



Adrian

 

[addjunkie]

That would be correct, i sold him a motor back in february. Clever guy, good with tunning electronics for motors etc. He was helping out the guy who first built a westlake powered bike then a bsa powered bike.

 

[dannyp]

the real question is how good is your notching, mig will forvive you a bit more in therms of poor fitup

 

[Jim Davey]

It will but it also hides cold lap more easily.

 

[backpurge]

the real question is how good is your notching, mig will forvive you a bit more in therms of poor fitup

Excellent point, my only concern is unless you really know what you are doing with the MIG some people have a tendency to use it like some sort of electrics sealant gun and just plough weld metal into a large gap or badly fitted joint to fill it up, this results in a weld with little or no penetration or fusion, parent material properties wrecked due to excessively high heat input and all sorts of other nasties but because they have a put down a big weld bead they thing it is strong enough for it's required application.
(Sorry Jim, just noticed your post above making the same comment)

 

[Jim Davey]

No worries, you took the time to explain it better.

 

[Richard.]

electrics sealant gun

No good for the bathroom tiles then ?

 

[Jim Davey]

If they were metal tiles it would be fine.

 

[Chris Stevens]

Excellent point, my only concern is unless you really know what you are doing with the MIG some people have a tendency to use it like some sort of electrics sealant gun and just plough weld metal into a large gap or badly fitted joint to fill it up, this results in a weld with little or no penetration or fusion, parent material properties wrecked due to excessively high heat input and all sorts of other nasties but because they have a put down a big weld bead they thing it is strong enough for it's required application.
(Sorry Jim, just noticed your post above making the same comment)

Millions of Japanese ERW tube frames have been made, and not ever heard of many problems with them being MIG welded? Home built chopper frame is something else entirely though, and I would guess some might be deathtraps, no matter what type of welding is used?

 

[Jim Davey]

One would assume factory Mig welders are trained to a certain degree. This is a discussion about the best joining method for a beginner to use. But yes, if the welding is that bad it won't matter what the process was.

 

[Chris Stevens]

One would assume factory Mig welders are trained to a certain degree. This is a discussion about the best joining method for a beginner to use. But yes, if the welding is that bad it won't matter what the process was.

Get the feeling that most Jap frames were welded by robots.......................

 

[Jim Davey]

In that case I would assume the robot gets programed by a competent welder and that the welds are inspected periodically as part of a QA system to ensure standards stay high.