Any suggestions as to how to improve new amal 289 pilot setting, very lean and cannot adjust this lean mixture to acceptable level with pilot adjustment screw.Anyone had any success it setting up these new amal carbs.Just cant get them dial in ...190 main correct needle and jet #4 slide Can anyone help?
new amal 289 carbs vey very lean on pilot
- Thread starter les dwight
- Start date
Dear Les,
The main jet and slide size are not going to effect your idle mixture. If you can not richen the mixture enough by screwing in the air screw it may be that you have an air leak or if the carbs are old the very small pilot fuel drilling may be blocked. They can sometimes be cleared with a very fine wire.
There is some good information at the link below with links to several sheets for tips, tuning, etc.
http://hitchcocks.sincordia.co.uk/premonobloc-how-it-works
I have been trying to find it on the forum, But no luck, I am sure Greg said he had trouble, Sent it back to the works, And when it came back it was fine, It was not that long ago, P.M. Greg Brulis maybe, Cheers Bill.
Thanks Bill, Yes had a few issues with the new 229/289 carbs....The one I sent back appeared to have a section of the pilot seat missing, either a machining or casting fault. Burlens said they found nothing wrong with it, tested it and returned it to me. Using them with the supplied number 4 slide, I found they are too lean, and will constantly spit back unless the choke slide is lowered enough to enrichen things, but you cannot ride the thing like this. A number 3 1/2 slide is much better....I machine 30 thou off the bottom of a number 4 slide to achieve the same result, and running with an air cleaner helps as well. It is amazing how a small change affects the running so much, but this has worked well on several of these carbs I have fitted to Twins and singles alike. Cheers and good luck......Greg.
Did I read somewhere that someone had found a bit of swarf jammed in the air screw passage?? Worth looking at....
I agree with Greg and Les. I have just recently fitted a pair of new 289 carbys to a bike and found that no matter what I did it was constantly spiting at idle and also on coming off idle. Yes it can be cured by lowering the choke slides but thats only proving that they were running lean. I had the manifolds off a few times making sure that they were sealed to the head. Valve guides were neat and I also sealed the carbys to the manifolds just to make sure that there were no leaks. The carbys came with number 4 slides so I fitted 3s' in order to start on the rich side. That fixed the spitting coming off idle. After all that, I could only come to the conclusion that they needed more fuel at idle. I have jet drills so was able to open out the fuel metering orifice a couple of points. This fixed it.
Phelps
Phelps
The one I had most trouble with had me so annoyed, that I completely disassembled it right down to removing the jet block. I figured, what else do I have to lose....it was only then that I could see quite clearly that a section about a quarter to a third of the needles seat area was missing, which made me think that because this is an air adjusting screw not a mixture one, like on a TT that it must be getting far more air even with the screw wound right in, than the correct balance of fuel to match it. I could not see how I could fix this easily, and especially since it was a NEW carb, so I returned it to Burlens, and after months of continuous phone calls, they told me that they could not fault it. I found this very hard to believe.....So when I finally got it back and installed, I had already modified the slides to my own preference and it seemed to adjust up and run ok......This is a real pain in the a--se seeing as the new 276 carbs seem to give good results straight out of the box....Go figure.....anyway this should give you an idea as to what you may find. Like most things on a Vincent, there is always something to "Fettle" before all is well, Cheers.........Greg.