Britbike forum Forums British motorcycles in general British motorcycles in general Speedo/Tacho Reference Numbers

Hi There--- does anyone have a link to a reference chart showing Smiths speedos and tachos reference numbers tied to bike applications.
Reason is that I picked up a job lot of gages and GP carbs over the weekend and want to know what I have got.
The tachos are: RC 1302/00 and RC 83
The speedos are SC 3303/01, MA and 3467/107/L.
The GP carbs are all 1 5/32" and I think probably from `1966 BSA Spitfires.
Thanks in advance for any info.

Some info here. http://thevincent.com/CometRevIndictor.html at least rotation and ratio for the tachs.

S467/107/L would be 1950s 6T.

Smiths Chronometric Speedometer

SC3303/01
Royal Enfield 500 Bullet, 700 Super Meteor and Constellation.
https://accessories.hitchcocksmotorcycles.com/38293

RC83 used on many BSA Gold Stars but not all of them.

Gordo

Thanks for the info, guys--much appreciated.
But---my thought still is with me---is there a published Smiths application list tying speedo/tacho numbers to bikes by manufacturer, model and year?
Just like there is one for Lucas equipment.

https://www.flickr.com/photos/[email protected]/2981803167/in/album-72157608455625820/

The answer is, sort of, but. Smiths published annual lists, some of which I've managed to buy over the years, or print out from obscure places on line, but what I've found is far from complete. I tried very hard to put together a complete list for just Gold Stars but have yet to find the numbers used on speedometers and tachometers in model year 1953.

Hi Tridentman, you wouldn’t have any spare GP slides and jet blocks would you?

BSA used them on the spitfire and also their Daytona Racer. I have a set (minus the match box float) but sadly they were disassembled (by the seller) and some of the parts either got damaged or missing.

Allan--- the GPs do not have slides but do have jet blocks.
All four of them are marked T10GP2 and stamped 1 5/32" (which is the size used on the 1966 Spitfire if I remember correctly).
The jet blocks are stamped:
48E
649H
714B
336E respectively.

The float chambers are all cylindrical rather than the matchbox type.

I will take photos tomorrow and post them.
HTH

Those numbers on the jet blocks were used to match the block with the carb body. Machined as a set. You might have to do some matching to get them to work.

32C602AB-6459-47D2-B525-6A263FA81289 by First Last, on Flickr

F0D1BEB4-690B-4A30-8ECA-4507E476F3A2 by First Last, on Flickr

Yes--the jet block stamping matches stampings on the carb body in each case.
Will try to post photos tomorrow.

Photos as promised

This is something I didn’t know. I was considering having a jet block made to match the one I already have.

It’s just a shame that Burlen have no interest in doing anything for the GP2 carbs. Gp3 a fitted to the Goldstar yes but not anything smaller.

MMan and Cyborg---many thanks for your posts--much appreciated.

I’ve never made a jet block, but I do have some TT’s that have mismatched blocks that need boring. I stand to be corrected, but this is my take on the situation.
Unless there is something peculiar about GP2 that is different from the TT carbs, then you could get one made. The jet block would be a little finicky to make, but nothing there that would be that difficult. I suspect the jet blocks were a select fit to the carb body, because (based on the TTs) there seem to be slight differences in fit between carbs. Once they were fitted, then the jet block and carb body would have been bored as an assembly and marked according.
So you could copy an existing one, but turn it to fit your body. Leave the bore slightly undersize, assemble the two and then bore the venturi. Depending on the situation, it would likely be cheaper and easier to buy another body/ block assembly with matching numbers. Might cost less and be worth more when you are done. Another thing to keep in mind is what sort of life did the carburetor have. Running unfiltered, there may be enough wear in the body that even with a new slide, there is still enough slop to necessitate sleeving the body. There is a fellow a couple hours south of here that does that for just under $200 usd. ( sleeves the body and uses a stock slide)