1974 850 Roadster: Amal Premier Carbs? (2018)

The 850 has been running a little rich but strong through the rev range; it easily floods if tickled prior to starting. I took my stock 932's off last night to check for foreign matter in the carbs and to check the floats. The floats appear to be the old plastic ones; the left seems be adjusted about right landing just below the edge of the bowl, but the right carb float lands significantly above the bowl. Also, one of the bowl screws in the right carb is stripped out.. sigh.. The jets are stock 260 and 106 with a 3.5 slide.

I have read here in the forum that some folks are having trouble with the Premier carbs. I am considering replacing the carbs but wanted to know if anyone has had a good experience with the premiers..

Thanks.
~998cc

I'd be interested in reports of problems with Premiers as well...especially since I ordered a set last week which has now arrived and waiting for me in TX (we return next week)! I ordered them based on all the good things I had read about Premiers...

Oh well - what could they need that I haven't had to do with the original 1973 Amals (true the bores, sleeve the slides, true all mating surfaces, adjust the float level, re-thread several stripped screw threads, etc) At least the Premiers have the easily-adjustable floats and the better body/slide material!

Hi.

I have new premiers. Two issues. The "matched" pair had different sized main jets. And I found I needed to change the idle jets from 17 to 19

Just wondering, did the supplier state what jets were supplied in the carbs? The ones I ordered specifically state that they come with 260 mains. It will be disappointing if they are different, not because it really matters as far as operation since I'll be installing different mains anyway, but it makes the supplier seem "unreliable."

Burlen (Amal) now fit 850 Commando Premiers with the '19' pilot jets.

http://amalcarb.co.uk/news/cat/news_amal/

"We are now fitting size 19 Premier pilot jets as standard to 850cc Norton Commando carburettors as this has been found to perform better than the size 17 fitted to earlier versions of the carburettor."

Drilling swarf, loose or mis-matched mains, gunk in the pilot jet passage, and propensity to run better on 19, as opposed to the (once) supplied 17 idle jets have all been reported.
But as far as I can remember, no complaints at all, once sorted/examined.

I had to strip and clean them as one had something in the pilot circuit. At least it's easy to do. I just wish I had done it before I fitted it.

So...sounds like a thorough disassembly/inspection/cleaning before install is a smart thing to do...

Mine work as designed, no issues. I did disassemble/inspect prior to fitting.

You need to strip the carbs and inspect them completely.
A friend of mine just bought 3 x brand new premiers for his triple. Two of the three carbs had problems with the internal drillings, so obviously none or very little quality control.
Some things just never change ! (hopefully yours are all ok)
sam

L.A.B. said:

Burlen (Amal) now fit 850 Commando Premiers with the '19' pilot jets.

http://amalcarb.co.uk/news/cat/news_amal/

"We are now fitting size 19 Premier pilot jets as standard to 850cc Norton Commando carburettors as this has been found to perform better than the size 17 fitted to earlier versions of the carburettor."

Click to expand...

I'm a bit confused with the numbering system. Is the 19 used (instead of 17) to lean the idle/starting mixture?
Since the part controls air flow is the 19 drilling larger than the 17?

19 has a larger fuel opening so it makes the mixture richer than a 17. The pilot jet size controls the fuel flow. The pilot air screw turning in or out controls the air flow.

Recently run a standard 750 with premiers on a Dyno and they delivered and metered perfectly to 6,000 rpm.

The new pilot jet numbering is the hole size in thou, so the old 25 becomes premier 17.

My 750 seems to run fine on the 17 but the 850 seems to want the 19. Anyone else see this pattern.

My 750 likes the 19. Especially noticable starting and cold running.

Yeah that's why I made the switch on the 850, popping and banging on startup. 750 never did that. Guess each one is a little unique.

998cc
Big improvement over the older Concentrics specially anodised slides, removable pilots and Stayup floats, check all passages and drillings are clear as suggested by other posters.
Make sure you specify an 850, which has the cutaway needle jet spray tube with matching needles and all the jets and slides your bike runs best on.
My 850 uses supplied #17 pilot jets but I have a set of #19 just in case. Left side is 2.0 turns out and right is 1.75 for a stable and reliable idle with Boyer or Trispark.

I removed the ticklers and blanked the openings as I don,t like fuel on the starter motor, so choke only for cold starts, every day at the moment as it,s my preferred transport just now. ( but winter is coming so Audi 5 cylinder turbo grunt and quattro drivetrain the way to go)

My floats needed adjustment, now slightly tilted down at the front to prevent leaks if the fuel tap was left on and also both slides stopped around 1mm shy of full throttle.
Reworking the carb tops restored full lift and they run beautifully from idle to redline on standard early 850 jetting but with optional #3.0 slide and K&N R-0990 twin filter.
Slides and inner carb body are in perfect condition after around 9000 miles so hopefully set for a big mileage and they stay clean, don,t leak or smell of petrol.

You need to check the fuel level in the bowl.
http://amalcarb.co.uk/optimising-mark-1-concentric-fuel-levels

No issues if set up properly. Installed premiers at the start of this years riding season. Idles like a rock and runs beautifully. Checked them over and set the floats at 0.8 under the bowl lip, also put in 19 pilots. Make sure passages flow properly and there are no air leaks in the system: manifold and exhaust.