Gearbox numbers

[nvmat1]

Hello everyone. My second post of the morning! I am slightly mystified by the letters that appear before gearbox numbers on the lightweights. I understand that 'G' is for the 250s and that 'M' is for the 350s? What are 'G R' and 'G S'? Grateful for any thoughts. Paul

[Rob Harknett]

Perhaps for 250 c.c. CS and CSR models ???

[John Jarrett]

GS is definately for the lightweight scrambler CS model , which depending on the year will have a different first gear ratio to the road bikes. Not sure about GR.

[Janet]

Always willing to be of assistance even if I'm not, I went looking for a number on the gearbox of my G2CSR. Not seeing it anywhere obvious, I removed the top cover but still nothing was apparent. I scraped off the oily crud and found G R then a four digit number. I have no idea what they refer to but at least you have confirmation of one model they're on. Maybe the R simply means road and S is scrambler. What does it say on the original basic G2?

[Rob Harknett]

Janet and John do seem to confirm my beliefs, I have a couple of lightweight CSR's and a G2, I've not taken off the covers to check whats on them.
Seeing the CS CSR & standard road bikes do have different gear ratio's, the markings in question must be to identify the model for which the gearbox is intended for.

[nvmat1]

Thank you all. Your posts have been helpful. It therefore seems that 'G' is for the early 250 road bikes, 'GR' is for the CSRs, 'GS' is for the scramblers and 'M' for the 350s.

[T]

* The gearboxes were basically identical , except for the clutch that was fitted = 1 , single row chain ( std ) 2 , single row , heavy duty = 17 tooth gearbox sprocket ( CS ) 3 , duplex ( CSR ) 4 , 350 ( with new gearbox sprocket + extra clutch plate ) . - Thus the clutch centre 'spiders' / mainshaft ends differed . that's it , sussed it !