Frame Lugs??

[chaterlea25]

Hi All,
I spotted this frame on Ebay motors in USA no.   330445528320

It has 4 welded mounts on the front down tubes and no cast mounts?
Its numbered CA7 1276 and described as a 54 road rocket frame

I havnt come across a frame with this feature before??

Cheers
John O R

[trevinoz]

John,
           1954 and early 1955 frames are like that. No cast lugs.

Trev.
   

[chaterlea25]

Hi Trevor,
I was of the opinion that some of the early frames have 4 cast lugs and the raised battery platform brackets which make them attracive to would be RGS builders ????
I have heard stories about export frames also having 4 cast lugs????
I dont know any of this for certain but I am trying to sort out these changes in my head,

inquisitive
John o R

[trevinoz]

Not true, John.
                         The '54/'55 frame has the same dimensions as the RGS frame except for the cast lugs, centre stand mount, gusset and pump mounts.
In '55 the steering lock was added.
Even if you managed to fit cast lugs to an early frame and modify the other bits, a clever bloke would notice that the early frame was oxy welded whereas the RGS frame was arc welded.
Some Police Flashes were exported to Australia with the RGS type four lug frame complete with single side rear wheel and swinging arm but had a steering lock and full width front wheel.
My '62 Big Valve frame has four lugs and so have all of the others that I have seen.
Hope this helps a little.
  Trev.

[chaterlea25]

Hi Trevor,
Thanks for filling in the gaps,
I have only seen the 4 cast lug frames on RGS's on this side of the world
Does your "Big valve" have the battery platform big or small gap?
Steering lock ? or other features??

On the subject of big valve heads I recently got a 1549 head from USA, It is in fantastic condition and as far as I can make out was never removed since it left BSA, the valves have BSA pt numbers and there is no wear on the seats /guides etc.
However it has /had the standard size inlet valves fitted ?? and the intake is  1 and 5/32in.

I fitted another 1549 head to the bike in the workshop (money pit ) that had the A7SS head on,
this one had a 1 and 3/16in.  inlet  ????

Cheers
John O R

[trevinoz]

Hi John,
           The Big Valve frame is just like any other GA7 frame except that it has the four cast lugs.
The 1549 head is the big valve head introduced in, I think, 1960.
The over-stamped 1571 head, as far as I know, has the same valves but, again, I am supposing, has the 1 3/16" inlet tract.
The big valves are not much larger than the earlier alloy head valves, around 1 7/16".

My 1571 head has these valves and not the 1 1/2" type that some seem to think belong in this head.
The 1 1/2" inlet valves are an over sized valve and are supposedly the maximum size that can be fitted.

Trev.

[chaterlea25]

Hi Trevor,
Thanks for the info, That was more or less the conclusions I had (before!!!)
What stymies these conclusions is that the two 1549 heads have different size inlets (no signs of modifications)
and that they had the smaller inlet valves????  1.450in

I have a 1571 head on my SR which has a 1 and 3/16 inlet tract,
This head was in a sad old state when I was given it (yes given it!!)
I had new seats fitted which were sized for modern hi flow valves (Neucleus) these have the stem thinned below the guide and an almost flat shaped head, whatever, they work well and the bike goes like sh*t off a hot shiny shovel!!
Regards
John O R

[trevinoz]

John,
            I am pretty sure that the 1.450" inlet valves were the largest ever fitted in the factory.
There seems to be a few "knowledgeable" people who claim that the RGS had 1.5" inlet valves fitted ex factory but I am again pretty sure that wasn't so.
Trev.

[chaterlea25]

Hi Trevor
That would agree with my findings!!
I also heard there were 1.5in valves but have never seen one in the metal
BUT, SRM list them
http://www.srmclassicbikes.com/catalogue/index.php?target=categories&category_id=62

Cheers
John