Binks carb

[jonathanjoy]

Hi I’m wondering if I’m getting my cables crossed. Does anyone have knowledge of the slides on a binks carb ?

Does the twist grip go to the larger slide ? what does the inner slide do ? does it choke when down ( covering the pertruding jets) ?

[BRIAN MARSHALL]

Just as on an Amal carb, the smaller inner slide is used as a choke. I am unaware of any choices of main slide. With the Three-Jet Binks you have no throttle stop screw, so have to rely on cable adjustment only. You also have no control of the primary air mixture, and all you can do with these things is change jets ! As I have said before on this website, I am not a fan of Binks carbs, BUT I do have LOTS of spare parts available….
Brian

[jonathanjoy]

Thanks Brian. What do I look for on the Binks for wear etc. Its just that the starting is so poor, I’ve set up the float level several times but it does seem to want too know ?

[BRIAN MARSHALL]

Hi, I perhaps should have also mentioned that they are hypersensitive to float level setting. The way to set it, as detailed to me by the late Jim Best, is to have the bike off the stand and on level ground. With the throttle and air slide both fully open, (so that you can see what is happening), you ease the body of the float chamber forwards until you can see petrol JUST start to emerge out of the shortest of the three jets, and then ease the float chamber back a gnat’s whisker from that, all with the aim of having the petrol level JUST below the mouth of the jet. You may need to keep drying out the area with a tissue while you are furtling about, and you may need a small mirror to help you see what is happening.
As regards the fit of the slides, they need to be an easy sliding fit, but not sloppy in the carb body. Martyn Bratby or Roy Dagger might be able to assist, but I’m not sure if the latter is still trading. Also I have loads of spares !
Brian

[jonathanjoy]

Thanks again Brian, I find it a bit difficult to see. so I’ve taken the carb off and mounted it at that angle on a piece of board so I can adjust the float level, then I intend to put in back in the bike at that adjustment 💡 hope it works, wish me luck.
Also you mention you may have spares, do you have a needle for the Binks ?

[BRIAN MARSHALL]

Both the Amal and the Three-Jet Binks on Flyers, Reps, and Sprint Specials have the float chamber angled at 38 degrees to the body, so your piece of board will need to be fixed to suit. Good luck ! Needle ? What needle ?!
I’ll have a good look through my two boxes of Binks spares to see what I have got. As one fetched £626 on eBay yesterday I will be trying to complete a couple to see if I can turn them into money to help with my current rebuild project !
Brian

[jonathanjoy]

Good Luck with the Bink’s stuff, seems incredible ! I suppose being twin float it attracted a premium. When I said needle I meant float chamber needle. I’ve been reading an article you wrote, on ignition timing ( ref Glyn Chambers) so It might be worth having the mag serviced, you say you look for the spark to jump 1/4″

[BRIAN MARSHALL]

The entire float chamber assembly on later Three-Jet Binks carbs is identical to the Amal one, so float needles are readily available, but be sure to specify that it is for a top feed type chamber. With the earlier very heavy bodied Binks, with a zinc float chamber top, that has “Binks 1920 Eccles Ltd” cast into it, you are out on your own as regards spares.
Your mag should be able to produce audible, cracking, blue sparks over a 1/4″ gap. Anything less than that, yellowish, and nearly silent, is suspect. I highly recommend the book “The Vintage Motorcyclist’s Workshop” by ‘Radco’ (Frank Farrington). It explains how to make a simple spark gap testing tool, plus lots of other very useful tips.

Brian

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