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By BobM
#88944
Never been able to get any of my bikes running 100% on an Amal, I have three new, over £380 worth! so I changed to new OKO carbs at £24 each and they run great now without the usual spitting, stalling at lights etc.
By Andy C
#91304
Time for an update.

I thought I had it cracked, with the premier +1 size larger pilot jet the bike would start reasonably well, would tick over OK, and went reasonably well, however the plug would always show it was running rich.

A couple of weeks ago I was at a loose end for something to so so I swapped the carb out for my old worn concentric, just as a matter of interest.

The transformation was amazing - first kick starting hot or cold after a "tickle" when cold, reliable tickover, changed from going "reasonably well" to going "like stink", plug shows it running a little rich but nothing like as rich as the premier.

Premier carb is now sat on a shelf in the garage, I am just enjoying riding the bike with the old "worn out" Concentric.

Apart from the larger pilot the premier carb jetting / slide / needle is identical to the old Concentric, really at a loss to understand why it prefers the old Concentric.
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By Presto
#91308
I realise it's obvious to the point of seeming stupid - but this sort of thing ought not to happen with a new carb. And equally obviously happens in only a fraction of cases.

Amal Mk1 Concentrics - standard or Premier - are fitted to 1000's of bikes and run perfectly. Some may want to disagree - but it's an indisputable fact - and has been so for over 40 years!

If this failing carb was purchased new then it ought to have been returned to the seller in the first few days who ought to have identified the fault and/or replaced it.

It doesn't make sense to criticise (as some in this thread have done) the design/manufacture of a perfectly serviceable make of carburettor because this one has an evident fault. I guess in a sense the fact that the engine is running well with a Concentric proves the point!
By Andy C
#91315
Presto - as you say this should not happen, I have used Amals on countless bikes over the years and generally have had no problems.

In hindsight I should have returned it, but I thought it was perhaps a tuning issue which was why I changed the pilot jet for a larger one to help with starting.

Doubtless it will just sit on the shelf in the garage and gather dust.
By mauri
#91322
so not not reread the whole thread.

what is our engine configuration?

open exhaust, open filter, type of cams, head porting, type of ignition,...........
By Andy C
#91325
For the record config is:

612 with compression plate fitted
Goldstar silencer (minimalist baffle)
Big valves - not a big head just standard head with valves opened out
"Performance" cams
Boyer "points assist" ignition
Carb is fitted with a K&N cylindrical filter

I'll not be tempted to put the premier carb back on, having too much fun with the bike now.
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By Adrian
#91329
mauri wrote:so not not reread the whole thread.

what is our engine configuration?

open exhaust, open filter, type of cams, head porting, type of ignition,...........
Not sure it makes a difference since Andy said:
Apart from the larger pilot the premier carb jetting / slide / needle is identical to the old Concentric, really at a loss to understand why it prefers the old Concentric.
This premier carb needs investigating,it seems. This any use?

http://www.britbike.com/forums/ubbthrea ... s/732259/1

https://www.triumphrat.net/threads/amal ... 2003888080

A.

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