Amal Concentric Premier Slide set point

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p400

p400

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What diam bit for initial slide set point?

Not asking about Triumph, simply a pic with rods up Amals to ck slide set and syncro action.

Bushman1.jpg
 
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Don’t think it matters. I believe the purpose is to set the relationship between the two slides. From that point count the turns on the slide adjusting screws to keep it the same.
 
Yep, I've used various size drill bits, long nails, small diameter dowels, etc. Doesn't matter. And noted you just want a way to tell if the slides are lifting together.

One interesting thing to try is to set them perfectly in sync when closed and then open the throttle with a finger touching one of the slides and stopping the throttle movement at the point where that slide JUST clears the body. Then put your finger in the other body and check to see if that slide is in the same position... ;)
 
depends on your slide cut away. #3=3/16", #3.5=7/32", #4 = 1/4". You may find however that you need to turn them both in evenly another 1/2 turn or more to get it to idle. Just make sure you give each carb the same amount of turns.
 
I know my eyesight is not what it was but no adjusters on the carb tops? Anyway. i put the slides in the palm of my hand, adjust (with some slack in the cable) so they both move at the same time. Then put the slides in the carbs, screw the idle screws in one at a time with a finger resting on the top of the slide until I feel the screw just bind on the slide. Put the caps on, turn each idle screw in 1 turn, then the air screws set 1.5 turns out and that is my starting point.
I actually start with the carbs off the bike to make sure they clear the bore at WOT at the same time. I also finish off with a manometer, I used to have a mercury one but it all evaporated I think.
 
As mentioned already, the drill bit is only to ‘sync’ the slides, size is therefore irrelevant. Personally, I use my finger to feel the point at which the slide just starts to move. Then put finger in other carb and close the throttle to see if that slide ‘settles’ by the same amount. Check each way a few time’s and you can get it pretty much cock on.

Before you start counting turns of the throttle stop screw, back them both out until the slides bottom out, then wind each in until it JUST touches the slide (easy to see with filters off).

Now you got slides synced and throttle screws matched. Now you can start counting turns.
 
MexicoMike said:
One interesting thing to try is to set them perfectly in sync when closed and then open the throttle with a finger touching one of the slides and stopping the throttle movement at the point where that slide JUST clears the body. Then put your finger in the other body and check to see if that slide is in the same position... ;)
Click to expand...
I do it basically the same but in a different order.

I adjust to where both slides disappear at the same time (same). Then a thumb in one carb and a finger in the other. Push on the slides, feel when they lift twisting the throttle and adjust the throttle stops to make that the same. After that I make sure that there is a little slack in the cables - in other words, make sure that the throttle stops and not the cables are stopping the slides.

If I have the carbs off, I expect to see between 1/32" and 1/16" gap at the bottom of the slide on the engine side of the carb. If all that works out, it should idle when started and just need tweaking.
 
The best way for me is to have the carbs off the motor and use a .040 wire gauge under the slide on the motor side. It is more accurate but less convenient. Then adjust the cables so the slides lift at the same time. I bought a DIGISYNCH and it is the best synchronizing tool I've used.
Whenever possible I make my own cables with inline adjusters close to the throttle.
 
Yes - nowadays I do the same as Marshg. I set the carbs so that the slides reach the top of the body at the same instant. But I have never found both carbs to stay perfectly in sync from idle to WOT. I suspect that the Madass throttle linkage setup would take care of that which is why I ordered one. Unfortunately, it will not fit under my fastback tank. :(
 
If you have to choose between synchronised at WOT or at partial throttle, it’s partial throttle that takes the priority.

The % difference is much greater just off idle, and virtually irrelevant at WOT. And it’s effects on running is much greater too.
 
Good point! In addition to the smaller percentage difference re throttle opening, on a typical day, I probably spend more time at idle at one stop light than I spend at WOT on the entire ride! :)
 
MexicoMike said:
Yes - nowadays I do the same as Marshg. I set the carbs so that the slides reach the top of the body at the same instant. But I have never found both carbs to stay perfectly in sync from idle to WOT. I suspect that the Madass throttle linkage setup would take care of that which is why I ordered one. Unfortunately, it will not fit under my fastback tank. :(
Click to expand...
When I use twin amals I always cable tie the splitter box to the frame,it makes quite a difference in keeping the carbs in balance
On my t160 I have mikunis but sadly no gantry
I have had to glue the cables from the carbs to into the splitter
This works perfectly but if one of those cables breaks I'll be stuffed
 
I've got Don's gantry system and it works well.
I use ball bearings not drill bits to synch the slides Just adjust so both balls drop together. I do stuff something in the manifolds just in case they roll through but they've never gone beyond the spray tube and always retrieved with a magnet.
I was shown this way to synch Tridents many years ago.
 

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The dimension for the drill bit setting 3.5 slide is 0.262" or 17/64"

Amal Concentric Premier Slide set point
 
Steves said:
I know my eyesight is not what it was but no adjusters on the carb tops? Anyway. i put the slides in the palm of my hand, adjust (with some slack in the cable) so they both move at the same time. Then put the slides in the carbs, screw the idle screws in one at a time with a finger resting on the top of the slide until I feel the screw just bind on the slide. Put the caps on, turn each idle screw in 1 turn, then the air screws set 1.5 turns out and that is my starting point.
I actually start with the carbs off the bike to make sure they clear the bore at WOT at the same time. I also finish off with a manometer, I used to have a mercury one but it all evaporated I think.
Click to expand...
Stop the presses. No adjusters on carb tops ?
 
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