Burman GB mainshaft lenght

[david.anderson]

Thanks Roger but that is a rigid HT (1954?) not a swing arm. I understood the 1955 HT swing arm was initially fitted with the GB11. I did try a GB39 (same cases as GB11) in my HT and it will not fit. In the swing arm HT the gearbox is much closer to the engine and I had to tilt it back from upright to avoid the timing case bolt. From memory (probably 15 years ago that I tried it) that meant different top and bottom engine plate gearbox bolt hole locations.
The photo of my HT shows just how close the smaller GB 47 outer casing is to the rear frame and timing case to engine plate bolt. There is enough room for primary chain adjustment with very little extra to spare.
Please ignore the incorrect earlier timing cases, modified footpegs etc. I do have the correct parts and will one day correct it but for now I do enjoy riding it on local bush tracks etc.
David

[Roger Gwynn]

All the records show that 1954-55 HT were rigid, s/arm arriving for the 1956 season. 9 of the 25 rigid HTs built list the gearbox, all GB11. There is one very early 1956 HT with a GB11 but all the rest on the first few pages of the despatch book list GB47. I wonder how they managed to fit it, there is nothing special listed about the bike, other than a lighting set.