Hi guys. I’m new to the forum and am building a cafe racer from a 78 GS550. Hope someone can help. I’m looking to buy a new mechanical tacho. Does anyone know the drive ratio for the GS? From some googling I’ve not found an answer, but I think it’s likely to be 1:4, 1:5, or 1:7. I would have turned the engine over and counted the revolutions of the drive cable - but the engine is in bits right now !