Amal Concentric Premier settings/jettings, California 850

Do any 850 owners running California fuel have any deviations from the stated standard jetting/needle setting/cutaways? I seem to be getting a fuel related cut when rolling on the throttle through 2000-3500 rpm, although it is not strictly repeatable. I've got the needles in their highest (richest) position already on my 32s because it ran poorly in the middle clip. The slide cutaway is standard. Just wondering what other riders are finding. I've had to richen my Velocette and some of my SU-equipped cars a little.

Any help or intel is appreciated.

Re: Amal Concentric Premier settings/jettings, California 85

Im in NYS. Have 74 850 and find it runs like a hose over 2500 and below not smooth or happy.
Tried needle in all three slots best middle but not saying much.
Granted, motor has only a 100 miles on it so Ill check in when I get it clocked up a bit.

Re: Amal Concentric Premier settings/jettings, California 85

In CA, you have E10 fuel, yes? Same as most of the rest of the nation. Yes, it requires MORE OF IT to perform on par with fuels available when these bikes were designed. So, yes, generally speaking, richen up from (vintage) stock settings. YMMV

Re: Amal Concentric Premier settings/jettings, California 85

I have new Premiers, an 850, and use the same gas as you do and mine does the same thing.

I suggest that perhaps there is no problem with your jetting, including the stock middle clip.

Every Commando I have owned and ridden has had a sense of "laboring" a bit between your stated 2-3500 rpm range, except in first gear, simply because the motor is not turning fast enough to smoothly provide instant throttle response in that range especially given its heavy flywheel.

Re: Amal Concentric Premier settings/jettings, California 85

I'm in California and have no such issue - running a single Mikuni 34, that I bolted on several years ago and never thought about since. Also own 2 Toyotas and a Mini - and never give a thought to carburetors (or injectors). Time to dump the pesky Amals? The last bike i had with Amals caught on fire (backfire, fuel on carb bodies from tickling, etc.), Never again, I've moved on.

Re: Amal Concentric Premier settings/jettings, California 85

Can you tell me:

1) What jets you are running, including pilot (How many grooves on the pilot jet)
2) What exhausts
3) Which Cam
4) Which air filter
5) What approx altitude

Did you get Pack 136? Or tell me the carb numbers. Did you get them from me?

I might be able to help. Mine were bolted on and pretty much perfect. the Pilot Jet was too weak so I added next size up (#19). How does it idle?

Cheers

Re: Amal Concentric Premier settings/jettings, California 85

In CA with a 75 n dual 932s, which I rebuilt. Probably original carbs from what I could tell n they definitely looked it. Anyway, middle clip, started 1.5 turns out then followed these suggestions. Idles at 1k and from what I can tell, solid all the way through.

Adjust the throttle stop screw so the engine speed is at a fast idle
Adjust the pilot air screw to increase the engine speed to its fastest possible Adjust the throttle stop screw to achieve your target idle speed
Adjust the pilot air screw again to increase engine speed to the highest possible
Finally, adjust the throttle stop screw to settle the engine at the correct idle speed (repeating the process may help achieve an even better engine idle)
NB – the sequence is
1. pilot air screw - fast
2. throttle stop screw - slow

Hope this helps.

Re: Amal Concentric Premier settings/jettings, California 85

Wow, I have stock carbies except I did add the anodized slides. Otherwise all brass is as delivered from the factory. Bike only has about 6 k miles on it. but I do not run e10 fuel. I go out of my way to stock and only use ethanol free fuel.

That said I have zero problems in that RPM range or any other range.

Does 10% ethanol really have that much of an effect?? that is only 10% of the fuel content that has what, 10% less BTU content? end result would only be about a 1% hit in the energy content going to the engine, right?

Re: Amal Concentric Premier settings/jettings, California 85

Romi3,

Usually after adjusting the mixture screw to highest speed I will turn it in 1/8 to 1/4 turn to richen up the mixture. This will help eliminate a flat spot and lean condition off idle.Search for Bushman's Carb Tuning Secrets online. It might even be in the tech section of this forum. Hope this helps.

Pete

Re: Amal Concentric Premier settings/jettings, California 85

Romi3,
I will also add that I am running Amal Premiers that I got from Jerry. I don't race, just cruise around back roads and an occasional highway run. They are perfect for my needs. Call Jerry he will be glad to help.
Stock 850 MKIII, with Dunstall Decibels mufflers. Standard idle jet, middle setting on needle, 280 mains and Iridium plugs .026". Boyer ignition W/ 31* timing. I have to set my mixture screw to fastest speed, and then in 3/8 of a turn. This is the setup that works for me. I live in New Jersey @ sea level.
Sorry probably more information then you needed.

Pete

Re: Amal Concentric Premier settings/jettings, California 85

Great info! Thanks, Pete.

Re: Amal Concentric Premier settings/jettings, California 85

Jerry Doe said:

Can you tell me:

1) What jets you are running, including pilot (How many grooves on the pilot jet)
2) What exhausts
3) Which Cam
4) Which air filter
5) What approx altitude

Did you get Pack 136? Or tell me the carb numbers. Did you get them from me?

I might be able to help. Mine were bolted on and pretty much perfect. the Pilot Jet was too weak so I added next size up (#19). How does it idle?

Cheers

Click to expand...

1) I have to have a look at those, although Idle is great with 1.5-2.0 turns out. No idle issue at all.
2) Non-crossover header pipes to stock-type replacement mufflers.
3) Stock 850 cam, as delivered from factory. Engine's never been apart in 17,000 miles
4) Stock air-filter setup with a paper replacement element.
5) Mostly I ride between 15 feet and 1500 feet elevation in Southern California.
I'll have to check about "Pack 136" and can certainly get the numbers. I got the carbs from JRC Engineering.

Re: Amal Concentric Premier settings/jettings, California 85

And thanks for that good rundown, Pete.

Re: Amal Concentric Premier settings/jettings, California 85

I live in Tehachapi, California which is at an altitude about 4000 feet and I use 89 octane automotive gas. My carburetor is set up with 260 main jets and 106 needle jets with stepped discharge tubes and matching needles. The needle is positioned at the top groove. Also my motorcycle is basically stock with standard air filter and exhaust system. With this setup my motorcycle runs fine without cutting out, has excellent throttle response, etc.

I imagine my bike could run a little better if I rejetted the carburetors however the places I ride from Tehachapi go to a lower altitude so I want to be on the safe side and not over-lean the engine.

Recently I went on a ride to my friends house in Wrightwood over the Angeles Crest Highway. The ride took me to elevations over 7500 feet and the motorcycle still ran fine. It had less power output which is to be expected but it did not cut out.

I did at one time have a problem with the motorcycle cutting out at high power settings and I traced the problem to the Taiwanese fuel valves not opening correctly. When the fuel tap was turned on the rubber seal inside rotated with the valve which nearly cutoff all of the fuel supply. I replaced the fuel taps with the British made ones and that solved the problem. At another time I have experienced power loss at full throttle and I discovered that I had not been moving the choke lever all of the way to the OFF position. So now I make a conscious effort making sure that the valve lever is moved all of the way over when riding.

Re: Amal Concentric Premier settings/jettings, California 85

The only problem I had was that the pilot was too small. I changed from #17 to #19 to get the perfect idle. It did idle before, but was hunting. Otherwise I bolted on the PACK 136 and all is perfect. I have the same setup as you except K&N. I am in California too. There should not be a flat spot. I think it's very difficult to assist diagnosing carb problems online as other variables need to be checked first (ignition, fuel taps, air leaks etc etc) and we don't know how that was done. I remember changing carbs to fix a problem that was surely carb related to find out that I still had the issue. Everything else seemed perfect and eventually after pulling the bike to bits I found out that the Boyer Power box was at fault. I only found it because there was nothing else it could be. I took a chance and ordered a new one and that was the issue. It had been shorting internally, periodically.

I always check the Premier Carbs before shipping. A few times I have found wrong Jets and replaced with the correct ones before mailing. I think you will need to verify the jets and slides are correct if you did not:
http://www.accessnorton.com/amalcarb-info.php

Where are you in California? (PM me)

Cheers- Jerry

Re: Amal Concentric Premier settings/jettings, California 85

Had dinner in Fullerton with my wife the other night.

I'm not convinced it is fueling and am not convinced it is ignition...

I am going to run it on the dyno next month with a sniffer to see where it is through the range and at various throttle settings and loads. Was also going to run some leaded 110 race gas in it to see how it responds in terms of throttle response and running quality.

Re: Amal Concentric Premier settings/jettings, California 85

My 73' 850 has stock carbs rebuilt by the PO and runs great on Chevron Super (91)...I did have to get the cable sync right when I bought it and occasionally have to fiddle w/ the idle mix and throttle settings. FWIW the PO replaced the floats and they were too wide at the pivot, this caused the floats to stick, the carbs to overflow, and started a fire :shock: .....easily fixed by filing the floats for a better fit but I nearly lost the bike.