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<\/a><\/p>\nAlthough, conveniently, this needle jet was made to accept the later small Amal main jets it\u00a0was badly worn and the likely cause of rich running low-down. I asked around but was unable to locate any replacement needle jets or needles for that matter. So, following a chat with the ever helpful (and patient) Martin Bratby I decided to look into producing an adapter that would allow 29 series needle jets and needles\u00a0to be used with the earlier Amac carb.<\/p>\n
After a few false starts I came up with a design that could be produce on the little Emco. It was tight as there isn’t much wall-thickness to play with if everything is going to line up correctly but I was pleased with the result. The photo above shows the Amac jet-block with an original needle\/main jet assembly next to\u00a0a 29 needle\/main jet screwed into one of the new adapters.<\/p>\n The next job is of course to try one on the bike to see how well it works. The plan is to start off with a 106 needle jet and\u00a0the middle-clip of a 29 needle.\u00a0I’ll probably adjust the position of the needle jet up\/down in the adapter to fine-tune rather than move the needle clip itself as the “correct” relationship between slide-needle-needle jet is of course difficult to establish when mixing and matching the 29 and 10MDY elements.<\/p>\n To help with this, I\u00a0have use of a decidedly un-1930s\u00a0Innovate LM-2<\/a> AFR data logger\u00a0that uses a\u00a0Bosch car-type\u00a0Lambda sensor rammed up the exhaust pipe to monitor the exhaust gases. Once lashed up on the bike, it is relatively easy to record the air-fuel-ratio at different throttle openings, engine speed and load. This makes fine-tuning of carburation using the modern fuels\u00a0a lot less hit-and-miss for someone with my lack of sensitivity in such matters.<\/p>\n","protected":false},"excerpt":{"rendered":" Having recently re-acquired my little Emco Compact 5 CNC\u00a0lathe I found time over the Xmas holiday period to experiment with a little project that I’ve had in mind for a short while. I had noticed that the ’30 M90 was … Continue reading <\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n