new carbs questions

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You sure you don't have intake manifold air leaks? Are you using a balance tube setup on the intake manifolds? Might want to check how tight the tube is if you are.

Doing one thing at a time is good advice. I never follow it, but it's still good advice. :) Moving the clip back to where it was and doing the plug change doesn't sound like a bad thing to do. Follow your gut. Of course, that might be what got you in trouble in the first place.

You should use resistor caps with the BP7ES non-resistor plugs with your ignition. They will work to fire up the motor, but the Pazon ignition won't like it over the long run. My Boyer ignition didn't like the BP7ES plugs with non-resistor caps, and apparently the Pazon is the same in a better looking package.
 
Plugs last. If you poodle around a lot as I do and then come on home on the dual you might find yourself in trouble using too hot a plug. Black plugs on the low and slow will turn a lot cleaner with a good engine after an hour at 75. And don't forget the
weather. It has been a cold spring here and the bike will run cooler and tolerate a lean mixture or too lean a mixture once warm.
You get to normal weather and things may look different in plug land. Makes you see why those still able to think logically buy
modern bikes.
 
Schwany said:
You sure you don't have intake manifold air leaks? Are you using a balance tube setup on the intake manifolds? Might want to check how tight the tube is if you are.
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But, there's no apparent problem with the carbs.
First post:
alan hodge said:
...spitting back and backfiring in exhaust upon first 12 mile jaunt......took little screwdriver with me and stopped every cuppla miles and screwed air screw in a bit til got smooth idle......bike ran great no flat spots ,,,,,overall was much smoother than single mikuni and pulled and pulled....
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What alan hodge appears to be concerned about is the dark plug colour which could be down to the N4G plugs being on the cold side for the type of riding and it would seem the plugs were the same dark colour with the Mikuni...

alan hodge said:
dark plugs was what i was trying to eliminate with 34mm mikuni
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The only apparent abnormality is the final pilot screw position being further in than what would be considered the standard 1 1/2 turns setting.

alan hodge said:
.......when i got home i let cool off...plugs dark ..AIR JET[screw] WAS ONLY TURNED OUT 1/2 TURN far from textbook 1 1/2 turn whaddy think? seat o pants o textbook?
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Schwany said:
You should use resistor caps with the BP7ES non-resistor plugs with your ignition.
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Resistor caps (or plugs) are not required at all for either Boyer Micro-MkIII/IV or Pazon Sure-Fire ignitions but are still recommended by Pazon and Boyer.
"We recommend fitting NGK 5K resistor (suppressor) type plug caps (or similar good quality make), but you can also fit non-resistor caps."


Schwany said:
They will work to fire up the motor, but the Pazon ignition won't like it over the long run.
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My Commando's Pazon Sure-Fire has always worked perfectly with resistor caps and BP7ES plugs as did the Boyer MkIII as I would expect (and what both Boyer and Pazon recommend).
 
I too am guilty of 2nd degree poodle dogging the majority of times, but let'er howl for a while this morning. Gonna looksee plugs after it cools.
Used to do the multi task thing and found that addressing one potential issue at a time solved my problems faster without inducing more. That was good advice indeed because it is then absolutely eliminated from the list.... unless of course it is an randomly intermittent issue. FE is spot on there... backfill the rabbit holes one at a time and you'll catch the rabbit.
 
put bp7es plugs in this morning and tickled and kicked once key off and tickled again and key on and bike started right up warmed up a bit and settled into nice smooth but slightly high (1300rpm) idle which slide screw took care of was going to ride and storm blew in so at least positive so far will try to ride in a day or so when weather clears
 
L.A.B. said:
But, there's no apparent problem with the carbs.
First post:


What alan hodge appears to be concerned about is the dark plug colour which could be down to the N4G plugs being on the cold side for the type of riding and it would seem the plugs were the same dark colour with the Mikuni...

The only apparent abnormality is the final pilot screw position being further in than what would be considered the standard 1 1/2 turns setting.

Resistor caps (or plugs) are not required at all for either Boyer Micro-MkIII/IV or Pazon Sure-Fire ignitions but are still recommended by Pazon and Boyer.
"We recommend fitting NGK 5K resistor (suppressor) type plug caps (or similar good quality make), but you can also fit non-resistor caps."

My Commando's Pazon Sure-Fire has always worked perfectly with resistor caps and BP7ES plugs as did the Boyer MkIII as I would expect (and what both Boyer and Pazon recommend).
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I'm just throwing stuff out there to see if it sticks. I never know what anyone's actual knowledge is when they ask for help, or give a shout out with "what do you think?" I know he owns other old British iron, but he did ask.

Alan said the motor spit and backfired initially. That is a carburetor problem usually. Although an intermittent short on one of the legs of the stator can do similar. I know that for a fact. Makes the spark weak, the timing goofy, and the plugs black. Anyway the spitting and backfiring could be an air leak or just a lean pilot. Or, a bunch of other things. He claims to have fixed the bucking with the 1/2 turn out on the low speed air adjustment. Results were he doesn't like the plug color with the Mikuni or the Amals. Got it already aware of it.

I mentioned the N4G plugs were colder a while back. I thought they were a NGK 9 equivalent, but may have been wrong. I don't really care if I missed the heat range by one number to be honest. I just figure the N4G plugs are colder than a BP7ES plugs, and a hotter plug would work better for producing the plug color Alan is looking for given his riding style. Not hotter than BP7ES. I mentioned trying the BP6ES, but at the time thought the N4G was in the same heat range.

I believe I essentially said that the non-resistor plugs would work better with the resistor caps. If not that is what I meant. I know about the Boyer ignition. I didn't know for sure about the Pazon and you already posted that info. I have not used resistor caps on my Norton in the 47 years I've owned it. I think that's how long I've owned it. I know I bought it and brought it home in boxes while I was driving a new Chevy L.U.V. truck.

The Autolite plugs I'm using are much better plugs than BP7ES plugs in my Norton engine. I'm not making it up, or trying to sell Autolite plugs. They work great though.

I'm letting Alan know what I know works exceptionally well for my Norton ignition system. I don't concern myself that much with Norton tradition. I only concern myself with what has worked for my use, and pass it along.

Based on my short time as a member here, I'm fairly certain that I would win the doing everything not recommended on Access Norton and making it work contest. LOL

I promise I won't post in this thread again. I will give a like to Alan when he gets that golden waffle plug color he is looking for.
 
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As for myself........ I like all input when I ask questions. If someone holds back something could be overlooked... Easy enough to glean through it all, so I say speak up when you've something to say because it may be of help.
 
Schwany said:
Alan said the motor spit and backfired initially. That is a carburetor problem usually.
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Yes, but apparently caused by the pilot screws initially being set too far out and corrected by further adjustment and no subsequent spitting back reported so that particular problem seems to have been rectified by the end of the first post.

Schwany said:
I believe I essentially said that the non-resistor plugs would work better with the resistor caps. If not that is what I meant.
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Ok, as the wording implied that resistor caps had to be used with non-resistor plugs: "You should use resistor caps with the BP7ES non-resistor plugs with your ignition."

Schwany said:
I know about the Boyer ignition. I didn't know for sure about the Pazon and you already posted that info.
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Yes, I had, therefore, I could see no reason for the: "They will work to fire up the motor, but the Pazon ignition won't like it over the long run." comment when you had no experience of the Pazon Sure-Fire.

Schwany said:
Based on my short time as a member here, I'm fairly certain that I would win the doing everything not recommended on Access Norton and making it work contest. LOL

I promise I won't post in this thread again.
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That's up to you. Unfortunately, when threads like this go on for several pages information becomes more difficult to follow and all I've attempted to do is point out that even from Alan's first post there doesn't seem to have been a "carb problem" only that the pilot screws were initially set too far out and caused the spitting back, but was more about Alan's concern regarding "dark plugs" (removed from an engine that had been idling and in my opinion probably not a reliable indicator of anything) and whether the jet needles were at the correct position.
 
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thanks fellers!!! i think i am on right track now...........a lot of knowledge on this forum i enjoy the plethora of opinions and friendly banter... stay tuned..
 
uh hate to reopen can o worms but.....is 'bush'-size pilot in 932 non-premiers equivalent to #17 pilot in Premiers? my reading tells me the 'bush' size is used in a lot of 930-series amals for a lot o different bikes including 650 BSAs and Triumphs so would theoretically be 'lean' or 'weak' for larger displacement larger carbed 850 commando is that right?
 
here's what happened over the last few days got idle down to a smooth 1100-ish RPM bike starts first kick hot or cold ran it up to 55-60 mph in all gears ran great very slight 'burbling' in exhaust on feathering throttle moved clip to 1st groove plugs still grayish but not black maybe leave well enuff alone PS new NGK BPR7EIX plugs
 
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well.....after a long wait i received an answer from Burlen concerning the needle clip position on these 932/43 932/42 carbs (for MKIII commando) when used on 1973 850 with peashooters and K&N type air filter..........drum roll please .....position 3 the lowest slot........since clip is currently in slot 1 that could explain why have to turn pilot jet air screw out only 1/2 turn to get rich enough ...............will give it a try and see
 
L.A.B. said:
Yes but the carb settings are (supposedly*) for the 850 Mk3.

*(As far as I'm aware the 932/42 and /43 specification was not used as 850 Mk3 carbs seem to have been 932/33 and /34.)

If you've been chugging around at 55 MPH then the carbs have probably spent hardly any time on the needles/needle jets.

After some initial spitting back possibly due to the pilot screws 1 1/2 turns out and the plugs being dark after the engine had been allowed to idle which might not indicate anything then I'm puzzled as to what this apparent carb/plug "problem" is supposed to be as it was originally stated that...


With the pilot screw down to half a turn suggests the pilot circuit was initially weaker than it needed to be and turning the pilot screws to half a turn has masked the problem.


"The Pilot Air Screw:—Turning the Pilot Air Screw “in” will make the Air/Fuel mixture richer. Turning the Pilot Air Screw “out” will make the Air/Fuel mixture leaner.

Because of how air reacts to how fast it is moving, with this instrument you want the Pilot Air screw to end up with a steady idle when it is 1 1/2 turns out from fully seated. If it ends up at 1, or less, turns out you should increase the size of the Pilot Jet. If it ends up at 2, or more, turns out you should decrease the size of the Pilot Jet. This instrument performs best when the air flow is passing through the orifice created by the taper on the Pilot Air Screw when it is 1 1/2 turns out. The orifice created controls the vacuum signal on the Pilot Jet, and thus fuel flow."

As increasing the size of the plot bush involves drilling then the pilot circuit can be richened by raising the fuel level.


spark plug cross reference

www.sparkplug-crossreference.com www.sparkplug-crossreference.com
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i have read much about the fitting of a 19 pilot jet in the 850, but nothing to the best of my knowledge on the 750..
Reading the above i suspect i do need to fit a 19 as mine is running best 1 full turn out on the pilot air screw
 
I've been running N4G's since Hitler was a corporal, and never any ill effects. Mr.Comstock speculated something to the effect that these hotter-than-spec plugs work because they stay cleaner without the deleterious affects such as melted pistons etc because the wire electrode is so small. All I know is they work, rarely foul and have never caused an issue. I bought 10 pair off Fleabay and sent the
Titanic to it's new home equipped with N4G's.
 
olympus said:
i have read much about the fitting of a 19 pilot jet in the 850, but nothing to the best of my knowledge on the 750..
Reading the above i suspect i do need to fit a 19 as mine is running best 1 full turn out on the pilot air screw
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Yes, you need a slightly bigger pilot jet for opium performance.
 
alan hodge said:
well.....after a long wait i received an answer from Burlen concerning the needle clip position on these 932/43 932/42 carbs (for MKIII commando) when used on 1973 850 with peashooters and K&N type air filter..........drum roll please .....position 3 the lowest slot........since clip is currently in slot 1 that could explain why have to turn pilot jet air screw out only 1/2 turn to get rich enough ...............will give it a try and see
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If you have the needle clip in position 1, that is the top groove, which is the weakest setting. I’m surprised that Amal recommend position 3 (bottom groove, richest setting) but I’d be surprised if it is the reason your pilot air screw needs to be screwed in so far. That is an indicator that the pilot jet is too small.
 
i sent them a message back stating (again) what type carbs and what type bike setup and saying it was bush type pilot in carbs will see what reply is.........
 
alan hodge said:
position 3 the lowest slot........since clip is currently in slot 1 that could explain why have to turn pilot jet air screw out only 1/2 turn to get rich enough
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I doubt it would explain it, as you said in your first post the needle was at the "middle" position when the screws were adjusted to "1/2 a turn".


If the needles had any influence on the pilot mixture then logically, the pilot air screws would have needed to be screwed in even further when you dropped the needles to the lowest (weakest) position but there's no mention of it, and if not, then raising the needles is unlikely to change the air screw position either.
 
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