new carbs questions

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Schwany said:
Probably weren't until they were modified here in the USA. It's very possible that the 850 I saw was modified by the owner.
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This has gotten really confusing. Are you talking about 850 Nortons or 850 cars?
 
Does anyone know if the NGK Platinums are amenable ro the resistor removal trick shown here:

 
Alan,

I want to say those resistor plugs will work with the non-resistor caps, but I don't have solid copper core plugs wires, or a Pazon to verify. I have a Boyer, non-resistor caps, stainless solid core wires, and use resistor plugs. Maylar thinks those plugs should work. At least I think that is what he is saying. Give it a go. At least they are the right heat range.
 
Schwany said:
Alan,

I want to say those resistor plugs will work with the non-resistor caps, but I don't have solid copper core plugs wires, or a Pazon to verify. I have a Boyer, non-resistor caps, stainless solid core wires, and use resistor plugs. Maylar thinks those plugs should work. At least I think that is what he is saying. Give it a go. At least they are the right heat range.
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Resistor caps or resistor plugs (as they are now more common) can be used with the Pazon Sure-Fire and is what Pazon (and Boyer) recommend although analogue electronic ignitions don't need either unlike digital ignitions which generally do.

"We recommend fitting NGK 5K resistor (suppressor) type plug caps (or similar good quality make), but you can also fit non-resistor caps."

"Why Do I Need To Use Suppressed Plug Caps?​

MKIII and MKIV do not require suppressed plug caps for operation although we recommend using supressed 5000 ohm plug caps. Micro Digital and Micro Power units must be fitted with supressed plug caps. Plug caps fitted with suppression resistors are usually fitted to prevent radio interference. Radio interference (noise) can cause more complex electronic circuits like radios and computers to malfunction."
 
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Schwany said:
My bad. I was under the impression that this Champion N4G plug was the same heat range as a 7 series NGK plug. I looked, and it looks like it is closer to a NGK 9, which is too cold. I suggested the 6 because it is only one step warmer than a 7. No big deal, because a 7 is not that hot. However, a 6 is considerably warmer than the Champion 4.

That NGK BPR7EIX should be correct and give you the waffle gold you desire. One would hope anyway. Unless you can't use a resistor plug as mentioned.
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Are you sure about N4G equivalence to NGK 9.....?
 
Alan The only difference twixt yours and mine is Wassell and Pazon. I'm non-R caps, solid Cu core leads and the plugs do fine. I'm still on the 1st set after 2 years service and have recently ordered a spare set.... My scooter is a '74 mkII with near 25,000 on the clock with original rebuilt Amal 932's & k&n filter.
 
maybe i opened this can o worms by moving clip to middle from top groove when i took them out of the box i sent email to amal/burlen asking that very question but probably wont hear back til first o the week i have some reg'lar BP7ES in shed and might put them in tomorrow and go for spin (carrying 2 N4G in pocket just in case)
 
Apologies again, but chasing plug types will not cover up what may be a carburation problem. If timing's okay, valve clearances are right and OE spec plugs are properly gapped then any discoloration outside of norm will be fuel/air related...
Possibly :)
 
The plug color I get via blasphemous plug selection. These plugs are in the self cleaning range. I could drop the clip a notch on the needles and richen it up a little to produce a bit more color, but no worries. Hard to tell, but there is a hint of tan on the insulators. Autolite APP5224 plugs, Boyer MkIV, TriSpark MOSFET reg/rect, dual 12V e-coil wire core wires non-resistor plug boots, 2 wire alternator, and small lithium LiFePO4 battery.

new carbs questions
 
marinatlas said:
Are you sure about N4G equivalence to NGK 9.....?
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It's all I could find on one obscure heat range chart. I got tired of looking. I based it on the 4, 59 in the Champion column of a heat range chart cross referencing with the 9 in the NGK column on that same chart, which could be very wrong. I couldn't find anything on that specific Champion N5G plug. What I looked at
 
Schwany said:
It's all I could find on one obscure heat range chart. I got tired of looking. I based it on the 4, 59 in the Champion column of a heat range chart cross referencing with the 9 in the NGK column on that same chart, which could be very wrong. I couldn't find anything on that.
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There was some info about lower Champion "N" numbers earlier.

Champion N3 N7 and Mick Hemmings

I've read a 1978 article in Motor Cycle Mechanics where Mick Hemmings says that N3 are better than N7Y for Commando road use but does not say why. I've got both here for a comparison and the tip on the N7Y is more projected but surely the heat range must be different as well. Any facts as to...
www.accessnorton.com www.accessnorton.com
 
alan hodge said:
note clip position these are the carbs i put on uhhhh mebbe i should not have moved clip to 2nd position....will find out tomorrow....mebbe i f**ked up and should have left as they came out of box......ddduuuhhh
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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...
alan hodge said:
...bike ran great no flat spots ,,,,,overall was much smoother than single mikuni and pulled and pulled.
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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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dark plugs was what i was trying to eliminate with 34mm mikuni and now these ones have achieved neither with either pilot is bush type in the new carbs
 
Which needle position is the clip in? Is the pilot a removable or fixed type. How did you set the slide gap and synch the slides. I've found setting the initial slide opening and synching the slides to be critcal to getting a good idle.
 
alan hodge said:
dark plugs was what i was trying to eliminate with 34mm mikuni and now these ones have achieved neither with either pilot is bush type in the new carbs
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Alan, I am intrigued as to why you do not try the correct standard plugs?

Hot-Rod colder plugs can be great in Hot-Rod engines. I run NGK #9s in my 11:1 920 for example.

But colder plugs foul easier unless everything is bang on, cos they don’t burn clean as easily.

As memtioned previously, at ‘a whiff of throttle’ you are using the pilot circuit and the slide cutaway. I suspect many Brit bikes might be slightly out on the pilot, especially on the standard Amal with no pilot adjustment like most Brits had / have, but the plugs get burned clean by harder riding. If you only ride in that area, they don’t get the chance of a good burn-cleaning.

If you fit standard plugs you’ll know they’re the correct heat range. Only then can you judge the colour, and the carbs.

Unfortunately, if you wanted to fine tune the pilot you‘ve bought the wrong carbs, Premiers have removable pilots jets and a range of sizes. The Mikuni has an even bigger choice of smaller incremental size changes. So hopefully all you need is the right plugs...
 
got some sleep today will put NGK BP7ES plugs in and move clips back to position #1 where they were out of the box and see what happens i just read in another post that the bush type pilots are weak for 850 so that might be a factor now for some coffee
 
alan hodge said:
got some sleep today will put NGK BP7ES plugs in and move clips back to position #1 where they were out of the box and see what happens i just read in another post that the bush type pilots are weak for 850 so that might be a factor now for some coffee
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I would try the plugs first whilst leaving the needles exactly where they are Alan. It’s always good to only do one change at a time. And personally I think your needle is correct where it is now.
 
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