Amal 289 Throttle Slide Cutaways
- Thread starter Chris S
- Start date
At least you can get your shed! I have to move some of the junk outside to even make a space to work in. Every now and then it just gets too bad and I try to have a good clear up. Inevitably the space I've created seems to fill up with junk again in no time.
Slides and cutaways seem to attract a lot of conversation. If I can rewind to my original posting, I was asking if anyone could confirm my understanding of the scale for cutaways which several of you have done. Thanks for that. My other point was that I have received some from Burlen that are not what I expected, just got 2 more from them and one is a 2.5 and the other a 3, but both are stamped 3. This was why I wanted to clarify the scale.
Greg's point however is entirely correct, if the plug is sooty after a steady ride then you need to increase the cutaway and vice versa if it is white and blistered. How you do this, milling, linishing, filing, nail clippers or whatever depends on what you have available. But, any method will work, just proceed slowly and measure twice, file once. As I said before, I now have a range of slides between 3 and 4 cutaways and once I am happy my twin is set right, if anyone wants to borrow them to set theirs up, let me know.
Chris
Greg's point however is entirely correct, if the plug is sooty after a steady ride then you need to increase the cutaway and vice versa if it is white and blistered. How you do this, milling, linishing, filing, nail clippers or whatever depends on what you have available. But, any method will work, just proceed slowly and measure twice, file once. As I said before, I now have a range of slides between 3 and 4 cutaways and once I am happy my twin is set right, if anyone wants to borrow them to set theirs up, let me know.
Chris
Of course an air filter will have some affect, but most carb's seem to work well and only slightly rich if a proper 3 1/2 slide is used, so I now tend to aim closer to the cutaway height of the number 4 slide. This experimenting does work, just takes a little time. The pilot circuit on the new 289 carb's can give issues too, either from tiny amounts of swarf in the passageway, or the hole size is not quite large enough. I feel they use the same drill size as they do on new Concentrics, but this is still too small. Hole size needs to be 0.018" to 0.020" but no bigger, or else it will run too rich at idle. Some I have checked from new, and you cannot pass an 0.018 " thou drill bit into the hole (I think this is a number 76 drill.......a number 78 is too small)This can only be done with the brass jet block removed. I will describe if anyone needs to know, Cheers...............Greg.
Entirely off topic: Tom, what's that car in your avatar? I was thinking Arnolt Bristol at first glimpse, but they're curved differently.
My guess is an Aston Martin, but now changed to Allard .........
Tom will no doubt answer that later. He is in the shed at the moment learning about all the bits of the Vincent clutch and where they go.
Did this yesterday on a pair of 289's and yes it is a 76 drill. Thanks for posting that info, much appreciated.
Do the 276 carburetors require the same drill size?
Never had the same issue on the 276 range, my guess is the cutaway/jets/idle circuits are better suited to the smaller overall size of this carb, though a blockage could be cleared with the use of a piece of fine wire and blow out with compressed air. This can only be done with the jet block removed from the carb body.