BSA B50 -500 APG Build

[Rex Schimmer]

Tom,
If you can gas weld you can TIG except it is easier! As with all welding, cleanliness is first, any place that you are going to weld needs to have the mill slag ground off of the steel, you cannot move the weld puddle with the tungsten so keep it away from the molten metal, reduces the time grinding new tips. Don't use big filler rod, i.e 1/16 or 3/32 except for building a trailer. I use .049 for most stuff even 1/8 wall tubing for cages.

A note regarding gas welding, before I had a TIG I gas welded several 4130  motorcycle frames quite successively, raced them both moto cross and desert and never broke them. The trick is use a slight carborizing flame  when you come to the end of the bead draw the torch away from the bead very slowly watching the weld puddle solidify very slowly. This assures that the last of the weld does not become a hard spot where cracking can start and a gas welded joint is naturally annealed.

Rex

[Peter Jack]

Rex, I agree with all you said. The interesting part I've found is that trying to teach someone who's experienced with oxy/acetylene can be a little frustrating as it takes a while for them to realize that moving the torch in and out isn't how you control the heat. Use the pedal! 

No pedal............. get really fast at adding filler rod.

Pete

[DND]

Hi Rex

Do you know Ronnie Scrima [ Albertson Olds dragster ] he was a real pro at gas welding 4130, saw him weld up Rocky Child's fueler and take the flame back away from the whole weld area and use the cooler flame to let it come down slowly in temp.

A real craftsman he was, he moved to TX in the 70's and i never got to see anymore of his handywork and missed learning tips from him too.

Don

[Rex Schimmer]

Don,
Never personally knew Ronnis but sure admired some of the cars he built, a true craftsman. I learned the gas welding 4130 from an old aircraft building book I used to have. There was a long time that gas welding was the only accepted method for welding 4130 tubing in small airplanes. Now days almost anything is accepted I think MIG is even used on some planes.

Rex

[Koncretekid]

Don,
Never personally knew Ronnis but sure admired some of the cars he built, a true craftsman. I learned the gas welding 4130 from an old aircraft building book I used to have. There was a long time that gas welding was the only accepted method for welding 4130 tubing in small airplanes. Now days almost anything is accepted I think MIG is even used on some planes.

Rex

I believe you're right that gas and maybe mig are acceptable, but the certification requires samples be submitted to the cert organization done in all types to which the certification applies.

It sounds like you guys want me to go buy that tig welder and get to work.  Nothing like practicing on your own ride.  Maybe I'll weld it and see if someone else will volunteer to test it.

Following are a few pictures of today's work.  The new lower left tube is now tacked in place.  You'll also see the tube I ruined while making the last bend.  If you notice the 2nd and 3rd bend are counter clockwise as viewed from the left side.  The last bend at the tail is supposed to be clockwise to bring the tube back to horizontal.  I bent it ccw as the others.  I got it straightened and re-bent, but it kinked the tube.  You can't do that.

Second photo shows back of bike with wheel in place and jigs to support new tail tube and seat/gas tank.  Third photo is my bend diagram, leftover from the first build, still tacked on the wall.  That is how I was able to get the bends the same.  But, the cro-mo tube has to be bent about 5* beyond what you need due to springback.  So this was somewhat trial and error.  If the motor will bolt back in without modifying the motor mount plates, I'll be lucky.  Fourth photo is the tube bender, first bend at the headstock.

[Peter Jack]

The bent parts of the ruined tube will supply more tubing for practice and the straight parts should still be usable for the smaller parts of the new structure. Lookin' good Tom.

Pete

[Old Scrambler]

Tom.....your the man.....I will stay with my modified chassis (only extended the swingarm) and rely on DAVE MURRE (my super builder) to get me safely down the salt.....and BACK

Question.....I am considering a B/B digital electronic ignition for my new T20 motor.....any advice?  We ran a home-made system triggered off of the cam and it worked.  Now would like to run off of the crank. Maybe a mag-system without the need for a battery.

Thanks for all you share with us.....and Merry Christmas  

[Koncretekid]

Dennis,
P.M. sent.
Tom

[Koncretekid]

I pretty well finished the new rear sub-frame, all with Chro-Mo tubing.  But first, I got to share some lobsters with my wife and my youngest son, Brian.  At 3$ per pound, they're hard to pass up.

The second photo shows what happens when the senior mind starts to revert back to that of a guppy.  I bent and profiled the front of this diagonal strut, marked the cut in yellow, walked over and put it in the vise, and promptly cut it vertically instead of horizontally.  Thankfully, it found a new home further back.  Rear view of finished subframe.  It looks simple enough, but each tube has a bend either at the front or the back in order to make clearance for the gas tank, which is 1" wider than the frame width, or for the back wheel, and must also clear the inside of the rear streamlining.  I think I got it right, should be about 10x stronger than the original due to stronger tubing and diagonals.

I still have to make a new seat hoop with the front gas tank mount, and finish drilling the front lower frame loop for the motor mount.  I can't do that until I re-assemble the motor and bolt it in to make sure of alignment.

[saltwheels262]

it looks like the new sub frame is going to work out well.

I usually measure 3 x and end up cutting twice. or thrice.

lobster is up to 3 dollars a pound in Nova Scotia ?

Bill

[Peter Jack]

Looking really good Tom. Are you going to buy the TIG now and weld it up yourself?

You're reminding me why I like going down there to visit my daughter and her family.

Pete

[Duck-Stew]

KK - Just read all 30 pages...  Seriously impressed with this build!  Hope to see you on the salt this fall...

Stu

[Koncretekid]

lobster is up to 3 dollars a pound in Nova Scotia ?

Bill

Bill,
Yes, lobster is up to $3 a pound now, but these are the real organic corn fed ones, not the inorganic ones imported from Bain Capital in China.  And, it's only $3 Canadian.  Most Americans think our money is just play money anyway.  I'll take all I can get.  If you have any you want to get rid of, just send it to me and I'll send you the equivalent in Monopoly money.
Tom

[wobblywalrus]

Your son looks happy eating that lobster.  Is he interested in racing?

[Koncretekid]

Your son looks happy eating that lobster.  Is he interested in racing?

Bo,
I have two sons and a daughter.  Although the oldest boy and the daughter have their MC licenses, they are not interested in racing.  My daughter could be, but she's busy with 3 children and a career in electrical engineering.  My youngest son, Brian, is a struggling musician who in spite of being near genius (my opinion) in his songwriting ability, can't even be bothered how to learn to drive a standard shift auto, much less a motorcycle!

KK - Just read all 30 pages...  Seriously impressed with this build!  Hope to see you on the salt this fall...

Stu

Stu,
Thanks for the complement.  I'm always anxious to meet new people on the Salt.  Unfortunately, for the two years I've been racing this bike, I've either been in line at staging, or at mile zero with the bike in the trailer, so I've only managed to meet a few people.  I've only run at Loring, ME and at the BUB speed trials, so far.

Looking really good Tom. Are you going to buy the TIG now and weld it up yourself?

You're reminding me why I like going down there to visit my daughter and her family.

Pete

Pete,
I'll probably buy that welder when I get to Colorado (save $100) in March and get some serious experience in before I tackle another project.  I really can't see myself being comfortable at 135 mph on a frame that I just learned to weld on!

Here's a photo of the fitting of the tailpiece.  It's tight, as it contacts the subframe along much of its length.  I think that will be good, as it will not depend on the Dzus fasteners to keep it from bouncing.
Tom