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ET: Engine (Twin) 32mm Amal premier Concentrics


favouritepants

Website User
VOC Member
Hi all imrunning 32 mm Amal Concentrics with removable pilot jet wit a no3 slide 106 needle jet needle in middle position 230 main jet and a17 pilot jet and my bikes idles well but bogs down on take of before launching away so I’m thinking bigger pilot jet your thoughts and or recommendations someone must be running these and I know every engine is different it any help would be great
Cheers
 

van drenth

Well Known and Active Website User
VOC Member
Try 107 needle jet with new needle.
or use slide 3.1/2
van Drenth JC
 

Normski

Well Known and Active Website User
VOC Member
If your idle mixture screws can be adjusted to give a good idle and are within the range of say 1- 2 turns out (but better 1.1/4 - 1.3/4) then your pilot jets are ok. A 107 needle jet would be richer a 3.1/2 slide leaner?
 

Bill Thomas

Well Known and Active Website User
VOC Member
I would try a 3.1/2 slide, Not sure what your petrol is like, But I have had to weaken my Bikes, With the Rubbish we have. Cheers Bill.
 

van drenth

Well Known and Active Website User
VOC Member
Be aware that there are different tapers on the pilot screws, and also the O rings which comes nowadays in the repair/overhaul kits are too small and after fitting those the pilot screw leaks air and will turn out by themselves.
Regards
JC van Drenth
 
Last edited by a moderator:

favouritepants

Website User
VOC Member
Be aware that there are different tapers on the pilot screws, and also the O rings which comes nowadays in the repair/overhaul kits are too small and after fitting those the pilot screw leaks air and will turn out by themselves.
Regards
JC van Drenth
These premiers are brand new but I will remember that whe it comes time to overhaul
 

favouritepants

Website User
VOC Member
If your idle mixture screws can be adjusted to give a good idle and are within the range of say 1- 2 turns out (but better 1.1/4 - 1.3/4) then your pilot jets are ok. A 107 needle jet would be richer a 3.1/2 slide leaner?
The front cylinder is at about 1 turn out and the rear is 1.5 out I’m thinking it needs more fuel or though it seems to be spitting back more on from cylinder then rear. I should mention I have not widened th manifold at all which could be a issue considering it’s going from 28mm manifold to 32mm on carby
 

Bill Thomas

Well Known and Active Website User
VOC Member
Sorry , If it's spitting back, It's weak, So forget what I said about 3 1/2 slide.
Maybe an air leak, Maybe too far retarded on the ignition, Was it OK before you fitted new Carb's ?.
Don't worry about the change in shape on the manifold.
Are the carb's sitting straight and level ish ?.
The other thing is float height ?.
Is this a tuned Engine, Or standard ?.
Cheers Bill.
 

Little Honda

Well Known and Active Website User
VOC Member
The front cylinder is at about 1 turn out and the rear is 1.5 out I’m thinking it needs more fuel or though it seems to be spitting back more on from cylinder then rear. I should mention I have not widened th manifold at all which could be a issue considering it’s going from 28mm manifold to 32mm on carby
Why did u do this?
 

favouritepants

Website User
VOC Member
Sorry , If it's spitting back, It's weak, So forget what I said about 3 1/2 slide.
Maybe an air leak, Maybe too far retarded on the ignition, Was it OK before you fitted new Carb's ?.
Don't worry about the change in shape on the manifold.
Are the carb's sitting straight and level ish ?.
The other thing is float height ?.
Is this a tuned Engine, Or standard ?.
Cheers Bill.
Standard engine has been sitting in pieces for quite some time just had overhaul pistons guides valves springs.carbs are straight quite certain no leaks but I will swap carbs around as I’m not getting a lot of response out of mixture on front carb. I will also check float level. I also thought maybe the 17 pilot may need to increase to maybe a 19 which the premier Concentrics have now
Cheers bill
 

Bill Thomas

Well Known and Active Website User
VOC Member
A 25 pilot might be worth trying, That's what a lot of people use on Mk1 and mk2 Amals.
Cheap and easy to try.
I was playing with a friends Mk2's the other day, And wanted to try 30, Because in would only run about a 1/4 out, But I ran out of time, And it ran OK on the road.
Just a thought, There is a tube in the middle of the Carb, Which is different for 2 strokes and another one for Norton's etc, I will find you the web site.
 

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