Amal every going to get this right

Situation: Recently acquired 74 Norton 850 Roadster not running well, starts easily first or second kick. sputters and backfires off idle to about 2500rpm, smoothes out some, backfires on throttle close, sputters on opening. Plugs black and sooty, runs uncivilized

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Switch ignition sides, cylinders run the same. Carb issue, thinking air leak between carb and head (had same problem with 78 KZ650). Order gasket set and pull carbs. Mains 260, Needle jet 107, soak carbs, clean pilot bushing with #78 drill, blow with compressed air , air comes out proper orifices. Fail to check needle valve clip setting... Reassemble and install. Hook up gas tank, gas leaks profusely from bowl gasket, tap bowls to no avail... wtf... pull carbs , disassemble, goop up bowl gasket, o ring and heat gasket with Permatex 2 as dressing, reassemble. Gaskets still weeping a wee bit of gas, carry on regardless. Starts easily, set pilot and throttle screws with individual cylinders running, get her to idle around 1000 with both cylinders running but tends to creep up to 1500. Take her out with a full tank, runs not too bad at first but not great, starts going downhill, missing farting and backfiring , gas leaking from bowls, goes on reserve after about ten miles, limp home. Runs worse than begin point, feel like teeing up carbs and driving into same pond as where my putter lies.

Back to forum, discover and study Bushman’s Carb Tunning Secrets, hmm maybe floats too high

Pull carbs, re-clean and get rid of goop, check floats, both above float bowl rim, boil bowls and gently tap float seats up to give approx 2mm gap, probably a little more. Check Throttle Needle clip, left on 3, right on top, set both to top. Reassemble and install, set pilots at 1 ½, throttle 4, hook up tank, now she won’t tickle on either carb. Kick none the less, after about 10, fires up. Running smoother, no backfiring when throttle blipped or held at 3-4k rpm. Left bowl weeps a tear of gas, right dry. Start her with left cylinder only, set pilot and throttle to idle at 1000,(had her thumping at 800), switch to right side won’t start , just 3-4 thumps every few kicks. Hook both plugs up and start, adjust right side pilot and throttle. Pilot screws approx 1 ¾, throttle 3 ¼. Right plug tan, left black and sooty, still rich with some vapour blowing out of left pipe. Wife yells, time to take her out to dinner.

Sitting back now with cold bottle of Sleeman Cream Ale in hand, contemplating the afternoon toils. Is left float too high and right to low, but neither tickle? Do I take for a test drive or pull and readjust float seats? If I adjust floats up to tickle, will I get bowl gas leak and rich crappy run. Seems to be a very fine line here. Also thinking there has to be a better way, rebuilt and sync’d a nest of Mikuni VM24’s on the trusty 78 KZ650 without drama. Hmm, time for another cold ale...

The posts here say to set the floats just below the rim (when pressing on the float, not the needle).

Hard to know where to start, first if you do have #107 needle jets they should be #106, on some 850s I make up #105.5 ( the jet # is the actual bore size in thou. of an inch).... the floats are now to low for the plunger to tap them so the seats must be tapped down to raise the float level ..or ..the plunger pins pulled out a little of the top buttons (the plunger pins don't have to bottom out)...... set the valve clearances...... strobe the ignition timing.....check that the slide needle on the left correctly entered the needle jet...... the float bowls are warped at the screw holes, tap them somewhat straight before fileing them true or they just get weaker as they get thinner.....good luck....... As for being more difficult than the Kawasaki ???? Click your heels your not in Kansas anymore....
I recently got in a Triumph that was freshly rebuilt/restored by neighbor of the owner, Wobbley relaced wheels, the auto advance assembled without bob weights, Long preunit valve springs coil binding to the point of bending pushrods, Smoking like a steam locomotive on dirty coal.... after inspecting it I told the owner that whoever did the work for him should not own tools of any kind, he told me it was rebuilt by a high school auto shop teacher. It explains why I have given up on co-op students.
If you are in the Niagara area of southern ont. I'm close by... Rick

Certainly not in Kansas and no ruby slippers to be found. Actually I'm in NIagara Falls Ont. My floats are all plastic unlike the the ones in the pic. I plan to pull the bowls and tap the float seats down a fine amount to lift the floats. I'll order up some 106's and check the needles to see if they are correct, workshop manual says 928/104. What's the best/proper tool to unscrew the timing inspection cover without marking up the slots, then I'll get the strobe on her.

Niagara850 said:

Certainly not in Kansas and no ruby slippers to be found. Actually I'm in NIagara Falls Ont. My floats are all plastic unlike the the ones in the pic. I plan to pull the bowls and tap the float seats down a fine amount to lift the floats. I'll order up some 106's and check the needles to see if they are correct, workshop manual says 928/104. What's the best/proper tool to unscrew the timing inspection cover without marking up the slots, then I'll get the strobe on her.

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Before you do that I would check the the actual fuel levels, you could be wasting your time playing with floats or making things worse.

OK, if you haven't already done this...
Take the carbs completely apart and true all the mating surfaces - bowls to carb body, carb body to manifolds, manifolds to head so that they are perfectly flat/true THEN recheck all the settings. I have found that with the oem floats that if the float tip is .060 below the rim of the bowl, they work perfectly on my 850. If they are level with the top, they tend to flood; if they are at .080, the tiklers tend to be erratic. I am not saying that you should use my .060, just that I have found it to work best on MY amals on MY commando. But the ture mating surfaces is vital to proper performance. It is really common to have distorted surfaces/leaky gaskets/sticky slides due to overtightening the fasteners. No sealing compound is needed and using it will just cause problems with "squeeze-out" getting into places that will cause problems.

If you have never done it, you can use a sheet of glass with some 240 followed by 400 wet or dry sandpaper (wet) to do the truing. Rub the parts in a figure 8 motion JUST enough to true them. The carb body-to float bowl is a bit tricky because the portion that holds the jet-holder prevents you from holding the body flat against the sandpaper. A fine file used carefully will do the job. Then be sure to just snug up the screws - that is all that is necessary. On the carbs-to-manifold studs/bolts, just enough "torque" to make the carb body/manifold surfaces meet is all you want. The orings will take care of the seal. Anything more will distort thebody/manifold.

IMHO, a large part of the problems with Amals is due to overenthusiastic tightening of fasteners and the subsequent warpage.

Niagara850 said:

Certainly not in Kansas and no ruby slippers to be found. Actually I'm in NIagara Falls Ont. My floats are all plastic unlike the the ones in the pic. I plan to pull the bowls and tap the float seats down a fine amount to lift the floats. I'll order up some 106's and check the needles to see if they are correct, workshop manual says 928/104. What's the best/proper tool to unscrew the timing inspection cover without marking up the slots, then I'll get the strobe on her.

Click to expand...

I can't recommend ordering from Amal directly enough. It took about a week and shipping was about $10. You'll save WAY more compared to ordering from a local dealer. And you can get the adjustable floats.

https://www.amalcarb.co.uk/

Are you running a points ignition? Sadly, incorrect gap can cause some of the same symptoms you describe. It is sort of a never ending circle of getting the igniton right and the carbs right. FWIW I recently put in new 106s and new needles (750) and had to go to the top groove in the needle to keep the mix from being too rich. Finally got it dialed in. Fixing the warped flanges is a must.

If you are going to play around with moving the clip on your needles, might as well order up some new ones. Once they get tweaked they tend to jump out of the slot and really cause confusion.

Russ

On the flat fit issue, the research report form about a decade ago plus my own verify the the casting process on 32 mm Amal give un even everything right out the box brand new. Then trying to fix this by nut nipping can bend the flanges to give the universal opinion of EVERY prior Amal nipper upper as ham fisted goon.
Put in boiling water, with vinegar even better as dissolved the white zinc oxide crust, then tap on flat surface, then fine tune abrasively as described above.

Its educational with carbs in hand to mic em to see how off one is to the other, bore size to roundness to spray tube height.

I always diddle float level so best idle is darn close to ideal 1.5 pilot screws out.
I keep at stuff till that occurs then fine tune off that factory intended baseline.
I too often end up with off tune carbs once the electrical issue solved and it can fire normal mixture regularly. Of both at once is too common too.
Oh yeah - when either of both carb and spark off a while, plugs tend to follow them and can drive yeah nuts till nothing else left to try occurs to ya.

hobot

naigara850 Have you cleaned the kill switch? are you running an electronic egnition? Phil

It has a Boyer electronic ignition, I took a look at the leads where fasten onto the pickup, seems ok. The PO has soldered and heat shrunk the electrical connections on the coils (and other connectors throughout the wiring system), I checked the coil resistance, met specs. The Kill Switch works and stops the engine, but haven't looked at that any deeper. I also leveled the the bowls using the glass /sandpaper method, the second time I had them out, they were slightly warped but leveled up quickly. I hope to get them back out this aft, I plan to change the needle jets to 106, get new needles, clips and floats and set up to original spec

First thing, air gap (any air gap) will cause a LEAN condition, yet should be seriouslyly checked. Continuity is ascential.

Secondly, in the photo below, the needle jet on the LEFT is a 106, RIGHT is 107. As one may suggest, 107 seems the leaner of the two, That being said, you should get the proper jetting installed(106). They also call for a 3 1/2 slide, 260 main and so on.

If both side are setup the same, with condition exsisting on both cylinders, then I would have to say that the floats are too high or the needle and seats are both bad (unlikely) allowing gas to flow somewhat unchecked (at least just enough to be messing wit yo mind) and it won't matter what jetting you use. Although timing may be the other factor, I am leaning (NPI) in this direction.

When you get those new needle jets and maybe slides, get the rebuild kit with the new floats and don't fiddle with the needle seat in the float bowl anymore. The tang on the new float is what you adjust just like the rest of the world.

Amal has just introduced new hard anodized and chrome plated brass slides for the Monoblock and the 600/900 series concentrics. Definatly worth checking out.

As Dave suggested, dealing directly with Amal is a good thing. Paypay, currency conversion, user friendly, non gouging.

Good Luck.

The #107 needle jet pictured is from the first concentrics made in 1968, they used shorter needles. the upgraded jets (left) have a larger needle entry but the bore size is .105, .106. or .107 thou. The needles for the 850 are identified by three marking rings above the three needle clip groves and are longer than needles with 2 ident groves. the longer needles fit in carbs that have the have the tube in the venturi cut in half as the 850 did stock. Rick

Thanks for all the advice. I found some 106 needle jets in the "boxes o parts" that came with the bike. They look like the one on the left in the pic, cleaned them up. Pulled carbs, set floats to 2mm, filed carb body to flatten, needles have the 3 rings above the top groove as described, set both on top and reassembled. Carbs tickled properly, bike started on second kick. Warmed it up well and set up pilot and throttle screws, idling nicely at 1000 rpm. No gas leaking from the bowls. Took her for a few laps around the neighbourhood. Ran smooth, pulling strong to 5-6k rpm, no backfiring or sputtering. The sound of a Norton reverberating had old men staring and children ran to the curb. Victory! Time to take her out for a cruise through the peach orchards and vineyards.

Made it 2 blocks, with a pop, she lost power and felt like it was running on one cylinder, could barely keep it running, limp home. Turn up the throttle screws to keep it running, misfiring and sputtering, idles for a bit, surges up to 1500, stumbles back down to 1000, repeat. seems like it runs on 2 cylinders then 1 and back to 2. I am pretty sure the carbs and intake manifolds are ok now. It ran well and should idle around 1500 where the throttles screws are now set. I'll check to see if one of the needles has jumps out, but I'm thinking ignition or some kind of wiring issue , intermitant open, short or a bad ground. So I plan to systematicly go through the ignition, wiring harness check the grounds, and clean the Kill Switch as well.

Hi Niagra,
Well I think we have all been there at some stage mate. It sure sounds like you are doing all the right things, and the short perfect running you had is enough to want you carry on! Be aware the needle jets, together with the needles do wear in time. So it is always nice to start off with none good un's. But your brief good running would suggest they are in good nick. Another area of the carb to look at, refering to the bushmans article, with the carb stripped and upside down, blow carb cleaner down the were the air screw goes, blocking off the other orifices and look closely at the little welch plug, in the float area. This plug covers the mixing bowl for the pilot air and fuel.
I purchased new carb bodies and after some very frustrating tinkering, by accident after removing the carbs for the cazillionth time found the plug on my new carb was leaking. Any leak here collapses the correct vacuum for the pilot fule to atomise. Also be carefull with your number drill and the little jet bush, this can get enlarged and eventually the carbs will not percolate good. if they are ovesize, you could try geting a MK11 pilot jet #25 I think and screw this in the thread inside the top of the float chamber.

HT regards Richard

Oh and if you are not getting anywhere, stop get some of your favourite beer and come back tomorrow.

Another area that should be loked at is a sticky valve, or for that matter a slightly leaky valve. Again from experience I now have a leak down tester, this is a great gadget to quickly rule this in or out. Leaky valve will show up in irratic por low speed running. With less noticiable performance at working RPM's.

Best

Niagara850 said:

I'll check to see if one of the needles has jumps out, but I'm thinking ignition or some kind of wiring issue , intermitant open, short or a bad ground. So I plan to systematicly go through the ignition, wiring harness check the grounds, and clean the Kill Switch as well.

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BOYER

If the pickup wires have not been addressed you HAVE to assume they are bad. Do not chase any other geese until the wires are properly sorted.


http://www.accessnorton.com/bad-boyer-t6996-15.html?hilit=boyer#p71429

Ignition issue for sure now. Took a good look at the pickup wires. One appeared to be pinched where it goes behind the plate (in swooshdave's pic the black one, in mine black/white). Took a page from my telephone tech days and gave it a good tug to see it would break, didn't but when I fired it up it ran on the right cylinder but I didn't have a spark on the left. Next I'll try to isolate and test the components that affect the side individually.

Do the wire's provide a spark to individual cyclinders ie black=left, red=right or does it send a spark to both cylinders at the same time with one being wasted? . I can see that replacing the pickup wires will be worthwhile none the less

Mike

The Boyer fires both coils at the same time on a wasted spark principle, so on each firing both plugs fire but only one is under compression and creates the bang. If one plug is firing then the fault lies after the Boyer eg the coils, coil wiring, plug wires, plugs and the earth wiring including the engine, boyer and coil earths.

The Boyer fires both coils at the same time on a wasted spark principle, so on each firing both plugs fire but only one is under compression and creates the bang. If one plug is firing then the fault lies after the Boyer eg the coils, coil wiring, plug wires, plugs and the earth wiring including the engine, boyer and coil earths.

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Not necessarily, Boyers are sensitive to which trigger wire is active first,so if one wire broken it may still fire both plugs but who knows at what time.
Could try key on plugs on head and flick an tug the trigger leads, if sparks >>>
Get Greg Faulths upgrade kit or fab your own out of the finest flexible copper leads you can source and maybe make nut bolt terminals, also backed up with dab of RTV.

Latest issue turned out to be a bad plug, was a fresh one too. Took her out for a nice 60km cruise. Not running too bad, much better than before. Still has an intermittent miss when on light throttle at any rpm. Boyer pickup wires next upgrade.