Settings for black airbox with peashooters?

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Matchless

Matchless

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I'm currently rebuilding a MK2a 850 for a friend & need to order a pair of 32mm Premiers. The bike has an RH10 head, standard CR, & black airbox, with balanced 1 3/8" pipes & peashooters. I'm thinking 19 pilots, 3 1/2 slides, 106 NJ with 2 groove needles, standard uncut spray tubes & 260 mains. Your opinions as always would be most welcome.

Martyn.
 
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260 mains works for me with peashooters and black box, think I also changed the needle slot position, raised it one position from memory but you will need to experiment. Premiers favour the 19 pilots.
 
kommando said:
260 mains works for me with peashooters and black box, think I also changed the needle slot position, raised it one position from memory but you will need to experiment. Premiers favour the 19 pilots.
Click to expand...
Thanks for that. Are you using balanced pipes, as having never fitted them to any of my bikes I have no real idea how they would affect things.
 
In my case, 250 mains works for me with peashooters and black box, it is no differnce with balanced pipes, only the noise ist not so loud, but still loud enough. Needle slot position I do not remember.
 
Mk 3 850 with 260 s here. It has 1 3/8" balanced pipes and open peashooters. Most of my riding is between sea level and 2000' . Home is at 350'.
This is probably a bit rich in the high mountain passes but it isn't a problem.
I had the needles in the 2nd notch from top for awhile, however there was a slight hiccup on acceleration after slowing to turn down a street etc.
Moving the clip down to 3rd from top position fixed that (four position needles)

Glen
 
Mine ran like crap until I went to a 3 from 3 1/2 . Made all the difference.
Black plastic airbox , 4 ring needles in mid clip position , 260 mains , 106 jets , no crossover pipes and into reverse cones. Plugs look great with a light grey on electrodes.
 
Thanks for all the replies. Am I correct in thinking you all seem to be using the needles with 4 I.D. grooves, as opposed to the standard four stroke type with 2 I.D grooves? Also, what shape spray tubes?
 
Matchless said:
Thanks for all the replies. Am I correct in thinking you all seem to be using the needles with 4 I.D. grooves, as opposed to the standard four stroke type with 2 I.D grooves? Also, what shape spray tubes?
Click to expand...
4 ring notched spray tube
2 ring flat top spray tube I believe
LAB will hopefully confirm
 
baz said:
4 ring notched spray tube
2 ring flat top spray tube I believe
Click to expand...

Yes, the 4-ID ring needle 928/104 is normally used with the stepped spray tube 928/107 (standard 850) and 2-ID ring 622/124 with the flat-topped spray tube 622/074 (750).

Edit: Although 2-ID needles and flat-topped spray tubes can be used on the 850.
 
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The main difference between the 4 and 2-ring needle, is that the 4-ring is leaner (fatter).
The difference in length is irellevant.
I find that, whenever Amal settings are discussed, there is a lot of talk about main jet size and needle settings, but not so much about the slide cut off, while in 90% of your time on the road, it is a
determinating factor.
I use the 4-ring needle, but in combination with an angled spray tube , much like nr 4 in this row:
( but unlikely you want to go that way..)

Settings for black airbox with peashooters?
 
ludwig said:
The main difference between the 4 and 2-ring needle, is that the 4-ring is leaner (fatter).
The difference in length is irellevant.
I find that, whenever Amal settings are discussed, there is a lot of talk about main jet size and needle settings, but not so much about the slide cut off, while in 90% of your time on the road, it is a
determinating factor.
I use the 4-ring needle, but in combination with an angled spray tube , much like nr 4 in this row:
( but unlikely you want to go that way..)

Settings for black airbox with peashooters?
Click to expand...
I very much agree with you on slide cutaway. Many is the time I have milled cutaways larger on Brit & Jap stuff. I don't ever remember using less than a number 3 on Amals. Many years ago I leaned off a set of slides (28mm Keihins) on a lightly modded CB750 SOHC & it made a massive difference.
 
Ludwig and All I assume the different cut aways on the spray tube have an effect on the velocity therefor richness of the mixture if so which type is richer the cutaway [Norton] or angled {Triumph]?
 
assuming that the 2 types create more turbulence therefor suction I guess the Norton one to be the richer, but does this carry through the rev range I suspect it does.
 
Matchless said:
I very much agree with you on slide cutaway. Many is the time I have milled cutaways larger on Brit & Jap stuff. I don't ever remember using less than a number 3 on Amals. Many years ago I leaned off a set of slides (28mm Keihins) on a lightly modded CB750 SOHC & it made a massive difference.
Click to expand...
I have done this many times too
Also I have shortened slides to richen them up and adjusted or shimmed the needle to suit
It's very satisfying tuning that bit of hesitancy out when you open the throttle
 
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