{"id":341,"date":"2013-12-29T17:19:31","date_gmt":"2013-12-29T17:19:31","guid":{"rendered":"http:\/\/www.sunbeamland.com\/wordpress\/?p=341"},"modified":"2013-12-29T17:19:31","modified_gmt":"2013-12-29T17:19:31","slug":"amac-10mdy-needle-jet-adapter","status":"publish","type":"post","link":"https:\/\/www.sunbeamland.com\/wordpress\/?p=341","title":{"rendered":"Amac 10MDY needle jet adapter"},"content":{"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 running rich at running-in speeds and sooting up the plug. Not a major problem, but closer investigation revealed a home-made needle jet in the Amac 10MDY carb.<\/p>\n

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Although, 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

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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

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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

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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 →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[48],"tags":[44,15,13,10],"class_list":["post-341","post","type-post","status-publish","format-standard","hentry","category-shop","tag-model-9","tag-model-90","tag-spares","tag-sunbeam"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t