1974 850 Roadster: Amal Premier Carbs? (2018)

Gentlemen, thank you for your thoughts and benefit of your experiences. Looks like I'm going the premier route too. Even though the 932's on the bike have some new parts, I'd rather have some assurance the problems will be resolved.

~998cc

Stripping the new carburetor(s), making a list of the calibrated parts nomenclature, checking float level and checking air and fuel galleries is sound advice as stated by members above in this thread. These pieces of sage advice should be applied to any new carb(s) you purchase in a factory sealed box; such diligence will bring you to, or very close to a V 1.0 success.

There are (still) a small number of application specific suppliers of carbs that do all the above as part of the listed carb price. The Concentrics seem to be more prone to needing float adjustment than the Premiers, but don't get alarmed the numbers aren't high, just random. The distributor I purchase Amal products from recommends that the float height be set by raising or lowering the needle seat, not bending the tang on the Stay-Up float (no "cheat" alternative for Concentrics). I was pretty intimidated the first time made this adjustment, but with a heat gun and two properly sized drifts it is easy and, actually quite satisfying. You will need to insure that the float pivot pin stays in it's recess at the bottom of the channel. Lastly push on the float arm where it makes normal, operational contact with the float needle. When you think you got it right, measure it 3 or 4 more times to insure repeatability.

Best wishes.

MexicoMike
Late reply but you can specify the jets and slides that suit your bike or just accept the standard settings.
I ordered Mk3 spec carbs but specified 260 mains and #3.0 slides and set the needles on #2 notch.

Thanks Kiwi! Got the carbs yesterday but I should have thought of that on my own! Oh well, I'm not sure what jets will be best for the altitude so I would have been guessing on the setup anyway. I have a selection to try. I would guess the same jetting that's in my current Amals would work but we'll see.

I'm trying to decide whether to remove the enricher slides in the Premiers or leave them and remount the control lever on the bike. I removed the slides from the original Amals back in '06. I'm wondering if maybe the Alton would start the bike from cold with just enrichers, no tickling. The slides were gone before I installed the Alton in '12 so I don't know. But it would be nice not have to do any tickling! I'll try them with the slides first and, if the bike will start from cold without tickling, I'll keep them. If not, I'll remove them.

The new Premiers and the V stacks are might pretty!

I’m pretty sure you have to tickle Amals even with the choke.

If you don’t, you’ll be risking being overly lean, something which can cause spitting back, which as I understand it, Alton’s do not like.

Unless you specified differently, they will come with #17 pilot jets which will almost certainly be too weak. Most seem to fit # 19s and I’ve heard of guys fitting #21s.

I fitted Premiers to a 650 Bonnie and the #17s were WAY too lean. It’s much better on #19s but may even bennefit from #21s... and that’s ‘only’ a 650...

Fast Eddie said:

Unless you specified differently, they will come with #17 pilot jets which will almost certainly be too weak.

Click to expand...

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

"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."

That’s good news !

RoadScholar said:

The distributor I purchase Amal products from recommends that the float height be set by raising or lowering the needle seat, not bending the tang on the Stay-Up float (no "cheat" alternative for Concentrics). I was pretty intimidated the first time made this adjustment, but with a heat gun and two properly sized drifts it is easy and, actually quite satisfying. You will need to insure that the float pivot pin stays in it's recess at the bottom of the channel. Lastly push on the float arm where it makes normal, operational contact with the float needle. When you think you got it right, measure it 3 or 4 more times to insure repeatability.

Click to expand...

When checking the 932's on the bike, the float level was way high on the right carb. Adjustment of the seats came to mind, but the float pivot pins in both carbs were held in place by peening/staking the slot to grip the pin. Wanting to avoid doing any damage attempting to remove the pins, I left them as-is. The carbs were inspected, components noted, cleaned and reassembled--high float level and all. I may take another look at them after the new carbs are checked, adjusted if necessary and installed.

Thanks!
~998cc

998cc said:

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

Click to expand...

Sorry to hear some have had problems.
Personally I've had them for a few years now with zero problems.

I disassembled the carbs - all looks good and very clean. Re the size on the pilot jet - 18 or 19 - is that size stamped somewhere? I removed the screw-in jet but I couldn't find any numbers on it.

I have Amal premiers on both my Commandos. I fitted #19 at the beginning, even though Amal told me #17 at the beginning. Idles well, performs well. 0 problems. Got about 15K now between both bikes. Very happy with these since the old concentric POS.

Cheers

MexicoMike said:

Re the size on the pilot jet - 18 or 19 - is that size stamped somewhere?

Click to expand...

The Premier pilot jets are identified by the number of grooves/rings near the tip.

https://www.britishmotorcycleparts.co.nz/amal-premier-pilot-jets
"Premier ID Grooves

1 Ring - 622/502-15
2 Rings - 622/502-17
3 Rings - 622/502-19
4 Rings - 622/502-21
5 Rings - 622/502-23"

Great, thanks LAB! They are 19's!

MexicoMike and Fast Eddie
I removed the ticklers start of the year and the bike e starts on full choke only and #17 pilots, cranking over a little longer in minus 4c /24.8f last week but anything above 5c / 41f it fires up straightaway.
My bike sits outside under a cover while I,m still using it for work so no warm garage, just ambient autumn temps. Fired it up outside just now at 7c/ 45f no problems at all. Real world scenario, no theory involved.

If you are in the California/ Mexico corridor, you should not need ticklers at all unless you,re wintering in the Sierra Nevadas, but you,re on the right track to try just the slides first.
The jetting on my carbs also performed well at over 7000 ft crossing the Alps in August, fuel consumption average the same as lower down. I think Premiers are great, can,t all be due to the efficient Fullauto head...

I like the velocity stack look too, will sort out a filtered setup for the Premiers over winter.

Thanks again!

As you noted - real world beats theory every time!

MexicoMike
Thanks again!
No problems but I have to ask, are you the gentleman behind the US flag?
(looks like the local village wrestler)

Well, that's me on the left (as you view). The village wrestler is a bronze of Winston Churchill. The location is on new Bond Street in London where my wife took the pic of me 'showing Winnie a pic' on my iPhone.

Here's a pic of the actual bench. I sat between the two and later cropped out Roosevelt and changed it to black/white. https://n7.alamy.com/zooms/46a36c08...osevelt-and-winston-churchill-on-a-e83k6b.jpg

L.A.B. said:

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

"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 got a set of Premiers about 2 years ago and didn't look at the jets before installing them. I was having issues with my right knee and I am just now getting back to sorting it out. Checked and the main jets are 190 and the needle jet is 106, I can't find any numbers on the pilot jets. Where are they located? It is popping on the left side and the right side is running a bit lean, blue pipe. I plan on running the valves tomorrow to see if that is the cause of the popping. What could be the cause of the right side running hot? Both carbs are adjusted the same and I used a electronic balancing tool to balance the carbs, what should I check next?
John in Texas

Just saw L.A.B. posting on the rings on the pilot jets to determine the size. Mine are 17's. Would those be right for a 70 750 Norton?
John in Texas

N0rt0nelectr@ said:

Just saw L.A.B. posting on the rings on the pilot jets to determine the size. Mine are 17's. Would those be right for a 70 750 Norton?
John in Texas

Click to expand...

That's a good place to start ---