003nahalf Posted April 19, 2008 Report Share Posted April 19, 2008 Can any one tell me or indeed point me in the right direction for info on web of the screw settings for my carb please. Just bought bike and will trial it tomo but 'she aint running right' Many Thanks. Jim Quote Link to comment Share on other sites More sharing options...
woody Posted April 19, 2008 Report Share Posted April 19, 2008 Pilot screw generally is 1 and half turns out as a starting point and then it is fine tweaking of both to get the final positioning right - how much tweaking depends also whether you want to run it with a tickover or not. As these bikes will ride well just on the throttle without use of the more modern clutch/brake technique they'll run better without a tickover but that is just personal choice. It's also easier to set up without a tickover. If you do run it without a tickover the throttle screw should be turned in just enough to give a tickover and then backed off very slightly until the engine just dies, don't turn it any more. Adjusting it this way means that if you have rolled forwards on the bike with the throttle shut, when you open the throttle again the bike should pick up immediately with no lag as it is already drawing in minute amount of mixture with the throttle closed, not enough to fire it but enough to help it pick up cleaner when you open the throttle again. You don't say which model Bult you have, earlier 250 had the MK1 Amal concentric, later models had the Amal MK2. Both have similar jetting I think, no personal experience of the later model with MK2 but MK1 has pilot 20, needle jet 106, main jet 150/160, needle on middle clip, slide number 3. Check what is in yours as who knows what may be in there after 30 odd years. The earlier bikes run pretty well on the original concentric Amals as long as they aren't worn obviously - after 30 odd years there is a chance it may be which could also be your problem, depends how much use it's had. The new concentric Amals that can be bought now don't seem to work as well, I've just fitted one to my type 49 Sherpa with the original jet size specs and slide number and it won't run like it should... Quote Link to comment Share on other sites More sharing options...
003nahalf Posted April 24, 2008 Author Report Share Posted April 24, 2008 Thanks Woody for this info kinda sussed her out on Sunday but retired anyway due to the old girl flooding like B@&*)$ Quote Link to comment Share on other sites More sharing options...
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