Facts about AMAL Mk1 carbs

[Howard]

The thing is , If you read Little Honda's post, It says the pilot jet is only for Two Strokes, Unless I have got it wrong ??, But I bet most of us have jets in !! My bike is running not too bad, And i can't face removing the jets and starting again. Funny a few years ago i loved messing about, But now i don't want trouble. I had less trouble years ago, When brother Ron and I built two 14" long Wal Philip type injectors. Cheers Bill.

I think you might have read that wrong Bill. The four stroke carb has a "bush" with an accurate hole through it that operates as a pilot jet. One of the many mods involves removing the bush and fitting a threaded pilot jet. Like you I have the 2 stroke type pilot jets and they work well.

H

 

[roy the mechanic]

When ordering a pair of mk1's from Burlens, the question of idle jets was raised, the answer was, "it will run best with idle bushes, not jets" As these are the manufacturers I thought best not to argue the point!

 

[Chris Launders]

I spent a year trying to get a good tickover on my recently obtained twin which is pretty standard apart from 32mm ports and mk1s and found it impossible then read an article on Vincent.com site about pilot jets and the built in pilot restrictors
Drilled out the restrictors,fitted #30 pilot jets,instant tickover.Also had an identical problem with my Norton Atlas as time has gone by had to gradually keep screwing the air screw in to keep a decent tickover,have had it 28 years kept on top of the maintainance ie tappets,timing,plugs etc, eventually ended up with air screw fully in,tried two different carbs,renewed manifold gaskets etc.no change,did same mod,ie drill out restrictor (smallest drill i have that will reach is 1.2mm)and fitted#30 jet.Ticks over best with screw 1 turn out now.This cannot surely be a coincidence, this must be to do with the current fuel compostion which has changed considerably in recent years and we all know you need much larger jets for alcohol,ask any vintage/drag/speedway racer.

 

[Howard]

Chrislaun,

I had a similar problem with a friend's Comet earlier in the year. New Mk1 Conncetric just couldn't be tuned to run slowly (Dunno why he asked me to look, I don't know what "slowly" is). The best/only setting was with the air screw fully in! After lots of head scratching, and comments like "flippin eck" I eventually discovered it had TWO pilot jets, one where the 4 stroke bush goes, and one where the 2 stroke jet goes. I took one out (don't remember which, but probably the "2 stroke one" and like magic we had an adjustable carb.

Roy - best not to argue with manufacturers, I think they're scared of litigation these days. The proof seems to be that on their new range they've got an adjustable float, and a removable pilot valve, which are the most common compaints from tuners. The other is the tube that sticks up into the choke (forget the name) cutting the back away (as per Norton carbs) makes a noticable difference, but I think Amal/Burlen list this as an option.

H

 

[Bill Thomas]

I did all the mod's, But my bike didn't like the tubes cut, So had to put them back as befor !! All Vins are not the same. Cheers Bill.

 

[roy the mechanic]

Never mind litigation Howard, if the manufacturer, who i have dealt with for 30 years , has even half a brain, he surely wants his product to work effectively! If we don't communicate they will not be aware of the aggravation we are experiencing!