ET: Engine (Twin) Amal Concentric Mk1 with 3.5 slides

craig

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I have my 1947 Rapide being set up with Amal Premier Mk1 928s with 3.5 slides and need help with initial slide set point.
I have been looking at Nortons for too long and have forgotten my Amal experience on Rapides.

Is not there a drill bit size I can use for initial slide set point?

Amal928_StartPointDrillBit.jpg


928 Premiers, 190 mains, 928/060DA-3.5 slides, 622/502-19 - .019 3 ring, 622/122-106 needle jets, 622/124 needles middle groove, mix 1.5 turns out. black plastic floats set level with bowl edge,
 
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John Reynolds

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The normal initial setting for Amal slides is 1/16" clearance measured at the engine side of the slide. This setting is made before the carburettor is attached to the engine/ carb adaptor. On the 3 1/2 slide, the cutaway is 7/32", so the drill bit required as per your illustration will be 9/32"
 

craig

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Thank you John, I will start at 1/16" or so.
In all my looking around at Amal rebuilding websites I don't find any reference to this 1/16"slide setting or actually any slide setting at all. Plenty of info on slide dimensions and cutaway sizes and part numbers.

cutaway-modifiedcolorweb.jpg
 

craig

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I found that 17/64" or 0.262" drill bit to be the best point to start the 3.5 slides with 928 Premiers.

928 Premiers, 190 mains, 928/060DA-3.5 slides, 622/502-19 - .019 3 ring, 622/122-106 needle jets, 622/124 needles middle groove, mix 1.5 turns out. black plastic floats set level with bowl edge,

Just shop tune with air fan for cooling for the time being.
Oh Yes, and electric start!

amal928_startpointdrillbit-jpg.38195
 
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craig

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I have been out riding 100 mile runs (47 Rapide with Grosset starter, Alton Gen, Podtronics reg, Shorai battery) and found that the cold idle set for electric start translates into very high idle when up to temp on a ride.

What advice might you Grosset starter guys have on this idle issue as to what you have found?

thank you.

20210723_152225.jpg
 

craig

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I tuned a better idle, reset idle speed, things were going well, and then the Rapide started running rough.
All I had done was disassemble the Amal , clean it, and reassemble.

20210724_ToughTune1.jpg


I forgot to report I did a couple of 100mph speedo check short runs just prior to this rough running.
 
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craig

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Got home with rough running (however it would idle just fine).
Plug check .

20210724_Plugchk.jpg
 
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