Britbike forum Forums British motorcycles in general Bsa gold star forum sonic weld frame

This is one of those new sonic weld frames using up a lot of my old flat track parts.
The cases are b33 with an early GS crank&with the quill tim cover and top breather.
It handles like a 250 bultaco but costs 5 times as much
I thought this would be of interest to someone with only a motor as he makes these frames for various motors

Nice job, Freddie!

David

very nice!

Hey, didn't you have an early 50's rigid frame you were rehabbing? How did that turn out?

yes its a 56 BB32R still working on it check it out

very nice, and thanks for posting the pictures, keep it going!

Nice GS sonicweld. I have one with a orginal frame. Iam looking to build a 250 also, i hope to find a old nickel plated frame. I would like to see how you mount the head steady to the frame. Now get some number plates on it!!

During The Era BSA reported a 1 to 1 1/2 hp gain not running a top head steady on GSs.
I and most other racers let the engine 'grow and flex' as it wanted.
I've not measured this but did read the letter.

However I've long thought a upper engine mount 'plate' picking up all of
the rocker box studs and then a bracket to the frame may work nicely to
put a evenly distributed load on the engine vs the OEM offset lug on the
head. This method is commonly done when a GS is fitted into a Seeley
MKIII road race frame that has no front down tube or front engine mount.

Wow- That is some awesome work there. Sweet !

the Ray Hensley rigid frames built for Goldstars come in two versions:
the original built for Dick Kelm in 1969 and ridden to an Ascot lap record by Tommy Rockwood http://vft.org/Museums/DonelsonsMC/DonelsonsMC.html
the others built as replicas when Ray returned to Cal and started Ray Hensley Innovations
either version should be called a Trackmaster as none were built at or by Sonicweld
Bill Andeson in Denver is building replica Sonicweld/Trackmaster frames 303-922-9295
Re: the B25
a few points from my BSA service school notes
Crankshaft: open oil feed holes to 1/8 and repolish
main bearing should slide onto journal
balance factor 65%
polish complete assembly
flywheel bolts 45 pds/ft
Sifton Carrillo rod or late model version of stock
Piston: find a Sifton 12-1 if you can
Cylinder: put liner in with Loctite Hot Strength Adhesive 306 (they slip)
releave liner for intake valve clearence
Head: port intake to 1 5/32"
port exhaust to 1 1/2"
Sifton valves and guides (intake is oversized at 39mm)
Sifton Collars, keepers and Springs
if not locatable compare Kibblewhite and R&D
Cam: Sifton high turnover with C-15 lifters
Rocker Box: 1968 or later (do not use the 1967)
Right side outer case: install breather at front top
Oil Pump:lap all surfaces, make sure gears turn freely upon assembly, loctite the screws
Gearbox: Camplate marked "69" not "T" (40-3294)
you will need a different mainshaft selector fork (40- 3033) (7/16" turned witness on spigot)
Countershaft Sprocket 14T or 15T
Change the motor sprocket to 18T (40-582) and the
clutch to 52T (40-3241) (the clutch is the same teeth as stock but this one lines up with the 18t motor sprocket) or you will need sprockets bigger than the wheel
Timing: start with 37 degrees
Sprockets: 1/2 mile 42-52T, 1/4 mile 56-68T
Exhaust: an A65 right side pipe cut to 34" from the head with a TriCor meg
Carb: 1 5/32 GP or a 30/32mm Concentric (if using the Concentric modify the float bowl) (I can send you the diagram) (don't believe the hype about Concentrics being bad carbs...they are not)
These are my notes from BSA service school
If I was doing it now I would probably send my motor and $ to Stan, Ed, or Gerald and await my "Rocket in a Box"
Also check the rules of the sanctioning body you are going to run with and make sure you build the bike and motor to the rules

the Ray Hensley rigid frames built for Goldstars come in two versions:
the original built for Dick Kelm in 1969 and ridden to an Ascot lap record by Tommy Rockwood http://vft.org/Museums/DonelsonsMC/DonelsonsMC.html

Tom at speed...Bike was still competitive with the newly allowed 750s.

Rob,

Thanks for posting that picture....a talented rider on a great bike.