Author Topic: new DYNA coils: running lean?  (Read 3713 times)

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Offline paulages

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new DYNA coils: running lean?
« on: June 27, 2007, 04:09:12 PM »
i'm gonna try and fit in some plug chops tonight, but in the meantime i'm wondering if anyone else has noticed a seemingly noticeable power loss after installing Dyna coils? stronger spark= cleaner burn= hotter and leaner combustion? all connections are good, and the sparks are nice and clean.

i have a 550F: dyna-s ignition, dyna coils, stock carb setup with airbox, stock 4-1, but have a homemade glasspack, with a 1 1/2" I.D. after installing the muffler, my top end gained noticeable power, but the low end  suffered a hair, as expected. now however, the off idle response is worse, especially after coming down from a 1/2+ throttle stretch. souds like lean symtoms to me, but i don't expect anyone to do cyber-diagnostics...plug chops will take care of that.

what i do want to know is: has anyone else had to jet up after installing lower ohmage coils?
« Last Edit: June 27, 2007, 05:01:09 PM by paulages »
paul
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eldar

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Re: new DYNA coils: running lean?
« Reply #1 on: June 27, 2007, 09:46:47 PM »
I will say this. When I switched to my dyna-s, I used the stock coils.  My spark is MUCH stronger, enough so that I am not sure I will bother getting new coils. My plugs are almost virtually white and you know what.... I and running rich and I have my plugs gapped further. It tries to flood out sometimes on start up but clears very quick, say after I lay of the choke in a few seconds. 

I really have to question the ability of a plug chop once the system is not stock.  I have the D8 plugs. Maybe you can try the D9?

Offline paulages

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Re: new DYNA coils: running lean?
« Reply #2 on: June 27, 2007, 11:56:53 PM »
I will say this. When I switched to my dyna-s, I used the stock coils.  My spark is MUCH stronger, enough so that I am not sure I will bother getting new coils. My plugs are almost virtually white and you know what.... I and running rich and I have my plugs gapped further. It tries to flood out sometimes on start up but clears very quick, say after I lay of the choke in a few seconds. 

I really have to question the ability of a plug chop once the system is not stock.  I have the D8 plugs. Maybe you can try the D9?

the 550 runs d7ea's.  i could try a colder plug, though.

i did plug chops tonight on the lucky 1/2 mile slight uphill stretch, right by our garage. idle and 1/2 throttle both turned up plugs that looked as if they had never even been run yet (new plugs...idle warmed up for a good 5 minutes before checking), but wide open throttle (is there a way to do this without going 100+ MPH? :o :o :o), turned up some pretty white plugs. i'm running the stock 98's right now. i'll try 100's next and see what that does. i think the exhaust was leaning it out to begin with, but the cleaner spark seems to have left me with a more thorough burn, and therefore hotter temps.
paul
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Offline phillip56

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Re: new DYNA coils: running lean?
« Reply #3 on: June 28, 2007, 05:48:54 AM »
I've got 550 vintage racer that I just got to run a few weeks ago. I've got a Dyna S and coils. I have open velocity stacks and a MAC 4-1 exhaust.  I started out with 110 jets and the needs down on from the middle. I just guessed that with that configuration of open exhaust and stacks I'd need a bit richer mixture. By the end I had the stock jets and the needles one from the top.  It was about 25C so warm for this time year and it still managed to foul the plugs after about 6 laps (about 10 minutes of racing).  The top end seems OK but the mid range is the problem.  Anyone ever have a similar setup run that rich?

Offline eurban

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Re: new DYNA coils: running lean?
« Reply #4 on: June 28, 2007, 02:18:32 PM »
I will say this. When I switched to my dyna-s, I used the stock coils.  My spark is MUCH stronger, enough so that I am not sure I will bother getting new coils. My plugs are almost virtually white and you know what.... I and running rich and I have my plugs gapped further. It tries to flood out sometimes on start up but clears very quick, say after I lay of the choke in a few seconds. 

I really have to question the ability of a plug chop once the system is not stock.  I have the D8 plugs. Maybe you can try the D9?

the 550 runs d7ea's.  i could try a colder plug, though.

i did plug chops tonight on the lucky 1/2 mile slight uphill stretch, right by our garage. idle and 1/2 throttle both turned up plugs that looked as if they had never even been run yet (new plugs...idle warmed up for a good 5 minutes before checking), but wide open throttle (is there a way to do this without going 100+ MPH? :o :o :o), turned up some pretty white plugs. i'm running the stock 98's right now. i'll try 100's next and see what that does. i think the exhaust was leaning it out to begin with, but the cleaner spark seems to have left me with a more thorough burn, and therefore hotter temps.
I have been collecting a few articles on plug reading.  I have yet to begin to master the the process but frankly I don't think that many people know what they are doing.  For a proper plug chop, the porcelain of the plug does not give a reliable reading for mixture . . .Unless perhaps you are looking (with a magnifying glass and a very bright light or one of those "scopes" that doctors use to look in your ear) way down to where the porcelain meets the metal body of the plug.  . . .Read these articles if you like; might save you some time and money spent on swapping out jets.
http://www.strappe.com/plugs.html
http://www.4secondsflat.com/Spark_plug_reading.html
http://www.dragstuff.com/techarticles/how-to-read-plugs.html

Offline paulages

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Re: new DYNA coils: running lean?
« Reply #5 on: June 28, 2007, 04:17:57 PM »
these articles have conflicting information... which one are you going to believe? not knowing a thing about any of these authors, i'll stick to what information i've received first-hand, as i've had success reading plugs accordingly. interesting read, though.
paul
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Offline eurban

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Re: new DYNA coils: running lean?
« Reply #6 on: June 28, 2007, 06:28:03 PM »
Reading the articles, there does seem to be a bit of conflicting / confusing info.  Particularly in the area of reading the plugs for heat range and timing advance.  I have just begun to understand a bit about what to look for in those two categories.  However they all pretty much assert that if you are looking at a plug for mixture that the porcelain is only a good indicator at the point where it meets the metal body of the plug.  The width of the ring at this point is the key.   New plugs that are properly chosen for heat range and when installed in an engine with proper advance should be pretty much be white on the upper easily visible nose of the porcelain after doing a good method plug chop.  Alot of the drag racers seem to grind off the metal threaded portion of the plug to easily view this mixture ring after a run.  Reading the base ring (the bottom of the plug that the grounding stap is welded to) for mixture is also a viable option but not particularly well discussed in the reads that I have found so far.  Kevin Cameron's (technical writer for Cycle World) Sportbike performance handbook pretty much says the same thing. . . .I am currently in the process of fine tuning my 836 project and have been deliberating on heat range, timing advance and mixture readings from the plugs. For sure, I am still learning this stuff.  What criteria are you using for your mixture readings?

Offline TwoTired

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Re: new DYNA coils: running lean?
« Reply #7 on: June 28, 2007, 11:13:26 PM »
You have to be careful which expert you idolize.  The drag racers all peak tune for the baro pressure and temperature of the day (or hour), and many of them offer expertise using liquid cooled engines.

Our air cooled engines for the street can't be peak tuned in the same way.  They have a much wider operating temperature variance, and cannot automatically adjust to altitude and baro pressure changes.  If you peak tune an air cooled motor on a cool day with low pressure, you could be in trouble on a hot day later on.

Something to think about.

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
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Re: new DYNA coils: running lean?
« Reply #8 on: June 29, 2007, 08:14:10 AM »
I have been wondering if a switch to the dyna should be accompanied by a switch to a colder plug as a matter of practice.  All because of the heat range. It seems that even with the D8 plug, I am running rich yet I feel that the plug may be getting too hot.  This morning it was about 55 maybe 60 degrees. Not COLD but cool and I only had to pull the choke half way and get good starting. This is after sitting all night so the engine is certainly not warm in anyway. It also seems to load up a bit on gas while sitting at a stop light and I can start to smell it after a bit. Clearly this is a rich condition but the plugs do not show any carbon buildup. This sunday I should have some time to look at it and maybe figure more out. Might also see about sealing my exhaust and that will change things too. Maybe do a sync? There is a little clutch rattle but not much.

Offline paulages

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Re: new DYNA coils: running lean?
« Reply #9 on: June 29, 2007, 08:50:26 AM »
You have to be careful which expert you idolize.  The drag racers all peak tune for the baro pressure and temperature of the day (or hour), and many of them offer expertise using liquid cooled engines.

Our air cooled engines for the street can't be peak tuned in the same way.  They have a much wider operating temperature variance, and cannot automatically adjust to altitude and baro pressure changes.  If you peak tune an air cooled motor on a cool day with low pressure, you could be in trouble on a hot day later on.

Something to think about.

Cheers,

i just can't help but be skeptical about internet "experts" about whom i have no frame of reference. i guess the same could be said about this forum, but at least there is more of a specific context in terms of the machine. i've noticed what you're saying first hand, lloyd, after pulling clean plugs after a 1/4 mile run on the same stretch and same throttle in different temperatures.

one of those articles specifically refers to the threaded portion as the mixture indicator, while one other refers to the base of the porcelain. which is it, then? i really would love to trust a knowledgeable source. from my experience, a lean mixture produces a pretty white electrode, and ground strap. rich= soot everywhere. how do i know? i ran plug chops where the only variable was changes in the carburetor, within a 30 minute time period. this may not be as specific, and i may not have had a microscope on the side of the road, but it presented good results.
paul
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Re: new DYNA coils: running lean?
« Reply #10 on: June 29, 2007, 09:34:33 AM »
Well it is easy to understand the temp change.  The hotter it is, the less dense the air is and so then the richer your mix will be and the opposite as it get cooler. Cooler air is more dense and that leans your mix.
Which is yet another indicator I run rich as my bike does better when it is cooler out.

Offline TwoTired

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Re: new DYNA coils: running lean?
« Reply #11 on: June 29, 2007, 12:03:50 PM »
i've noticed what you're saying first hand, lloyd, after pulling clean plugs after a 1/4 mile run on the same stretch and same throttle in different temperatures.

Perhaps this will help.  Probably just bore some people, though.

A liquid cooled engine has a temperature governed thermostat to vary the cooling effectiveness of the device being used to keep the combustion chamber temperature constant.  It's not perfect, but when it is working, it does confine the range of temperture variance and provides an fairly consistent path for combustion heat to flow towards. 

Our air cooled engines have cooling fins.  They don't get larger or smaller when outside air is hot or cold, and this effects their ability to transfer combustion chamber heat to the surrounding air.  Worse, headwinds and tailwinds, or the amount of airflow moving past the fins is variable under street conditions.

The perfect fuel mixture conditions we seek, are when all available oxygen in the chamber finds all the hydrocarbons during the combustion cycle. It's called Stoichiometric Combustion.

The oxygen content is governed by temperature, barometric pressure, and humidity in the air.
- Humidity has volume and as such it displaces oxygen in the combustion charge.  It also slows the flame front as the charge ignites.
- Barometric pressure, either from wandering air masses about the planet, or changing altitude, effect how many oxygen and fuel molecules can be present in a given volume, due to the compression weight of the all the air molecules stacked above it in the atmosphere.
- Temperature effects the spaces between molecules, and thus the total population of the fuel and air molecules in the volume of charge being burned.

While the above factors effect a water cooled engine as well, the cooling fin heat transfer efficiency is also effected by these factors.

Cooling fins don't transfer heat as rapidly to hot, dry, thin air, as they can to cool, "wet", heavy air that contains many more molecules to retain heat while passing in contact or nearby the fin.

Heat is not picky about its avenue of conduction.  Engine heat will transfer into the incoming fuel air charge also.  This is significant not only from a charge density aspect, but also from a fuel flashpoint aspect as well.  Start with the fuel temp, add ambient temp, add compression heating effects, add combustion chamber latent heat, and all these must tally below the flash point of the fuel, or the charge will all detonate before the spark initiates the fuel burn.  If the piston is still on it's way up, it crashes into the explosion before it can be repelled by it.

This is one reason why our air cooled motors have to run on the rich side.  "Rich" helps cool the engine and helps remove latent heat from the chamber.  The incomplete burn keeps combustion temps down, too.  It gives a "cushion" whereby when the engine is operated in the "corner cases", such as when the engine is hot, the air is hot, the humidity low, and the barometric pressure is high, the engine won't begin to detonate and self destruct.
 It is not as efficient as an engine operating in Stoichiometric conditions.  And, it is one reason why so few air cooled motors meet EPA mandates.

If you want to read plugs like a drag racer with a liquid cooled motor, you'd better do it on a 110 degree day, with a tailwind, low-to-no humidity, below sea level, with a deep high pressure area firmly entrenched throughout your test period.  Then realize that at all other times, your plugs ought to look on the rich side.

 Because the SOHC4 engine is actually overcooled by the fins in all but the most extreme conditions, the base ring will always be black/sooty.  The engine head and thread base must keep well below combustion temperatures to maintain a significant heat draw from the combustion chamber.  However, you will need temperatures sufficient for the plugs to self clean. The center insulator porcelain near the electrode tip should be near white.  Graduate to tan as you look down into the plug body, then dark brown and black near the bottom where the cylinder head maintains a temperature below that of combustion.  This is what a plug should look like after 500 miles in varying conditions.  New plugs on a brief plug chop run will begin to show this deposit pattern, but it will not be as developed as one with 500 miles of varying conditions.

Another factor in the plug chop method is power output.  The plugs give a good initial indication, but time and distance calculations tell about the power output.  If you start rich and gradually lean the mix on successive runs, the times will diminish until you reach a peak for that motor under those conditions.

One final note, drag racers are concerned with engine life under max power for 1/8 or 1/4 of a mile.    Do you really want your street bike to have a rebuild schedule equivalent to this?  People that live on the edge, sometimes fall off.

Cheers,


Lloyd... (SOHC4 #11 Original Mail List)
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Offline doug_id

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Re: new DYNA coils: running lean?
« Reply #12 on: June 29, 2007, 12:46:01 PM »
Thx TT.....that was an informative read...

I think I personally achieved "Stoichiometric Combustion" last weekend after eating beans & rice and drinking a couple of beers!    ;) ;D

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Offline eurban

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Re: new DYNA coils: running lean?
« Reply #13 on: June 29, 2007, 07:29:57 PM »
Couple of observations here.  Regardless of whether an engine is air cooled, water cooled, running nitrous etc etc its spark plug can show valuable information about its state of tune.  Understanding how to "see" this information is not so easy.  Most of the articles I have found are indeed focused on water cooled car engines but the indicators (for instance . . . location of the change of color on the grounding strap, location of the blue "timing lines" on the ground strap, deposits on the base ring of the plug, width of the mixture ring at the base of the porcelain, presence of peppering or aluminum deposits on porcelain, softening of the profiles the the electrode etc etc etc etc etc)  that these articles mentioned are certainly visible on my cycles spark plugs.  What I want my air cooled cycles spark to ideally look like might be a bit different than auto drag racers plugs but I can't make any educated adjustments without knowing what types of things to look for. Sure, tuning a antique air cooled motorcyle engine for max power within a hairs bredth of detonation on a 50  degree day a sea level isn't a good recipe for all year reliability but if I could actually learn to read my plugs that accurately then I certainly could be smart and leave some "cushion"  BTW the Gordon Jennings article is air cooled  motorcycle specific and written by a Cycle Magazine technical writer in the era that our bikes were made. . . .  Paulages you originally asked if a adding a Dyna ignition would cause your bike to run lean.  I doubt it.  What I do think it has done is changed the appearance of your spark plugs. Stronger spark?more advanced spark? (just a few degrees extra advance can really crank up the spark plugs temp!) and your porcelain now looks clean and white.  Your original point of reference might be gone; the plugs might be burning off the deposits that you are used to seeing.  What to do?  I guess you could shove a colder plug or retard the timing till your point of reference returns.  You could also richen up the mixture till it cools down the combustion temps enough for your point of reference to return.  This might not yield good performance however.  You could also be a bit more open minded and see if you can make a sense of some of the info I offered (its not nearly as contradictory as it almost seems you want it to be!)

Offline paulages

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Re: new DYNA coils: running lean?
« Reply #14 on: June 29, 2007, 10:20:05 PM »
Quote
Paulages you originally asked if a adding a Dyna ignition would cause your bike to run lean.  I doubt it.  What I do think it has done is changed the appearance of your spark plugs. Stronger spark?more advanced spark? (just a few degrees extra advance can really crank up the spark plugs temp!) and your porcelain now looks clean and white.  Your original point of reference might be gone; the plugs might be burning off the deposits that you are used to seeing.  What to do?  I guess you could shove a colder plug or retard the timing till your point of reference returns.  You could also richen up the mixture till it cools down the combustion temps enough for your point of reference to return.  This might not yield good performance however.  You could also be a bit more open minded and see if you can make a sense of some of the info I offered (its not nearly as contradictory as it almost seems you want it to be!)


i said pretty clearly that i would love to have such a frame of reference i could trust-- all i pointed out, was that there were clear contraditions between the articles, and given that i know nothing at all about the authors, i have no idea what to believe after simply following a few links. also, you seem to have misread my initial post. i didn't change timing at all, only the points and wires. granted, a cleaner burn could certainly affect or exacerbate an existing problem, but maybe i just misstated the question to begin with. i realize that a cleaner burn can't really make the mixture more "lean," but a cleaner burn could reduce the cooling effect of a less thorough and therefore richer burn. this could also make the timing want to be in a different place, sure.

i read all of this with a very open mind--i'm just a skeptic. being a skeptic is not the same thing as being close minded though. my personal observation is that it is hard to get any real reading in brand new plugs after such a short run unless you have extreme conditions (such as really rich mixture), and running longer than half mile at a fixed throttle (my wide open throttle run... :o :o :o :o) is near impossible.



lloyd--more good reading.
paul
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Offline eurban

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Re: new DYNA coils: running lean?
« Reply #15 on: June 30, 2007, 05:24:19 AM »

i said pretty clearly that i would love to have such a frame of reference i could trust-- all i pointed out, was that there were clear contraditions between the articles, and given that i know nothing at all about the authors, i have no idea what to believe after simply following a few links. also, you seem to have misread my initial post. i didn't change timing at all, only the points and wires. granted, a cleaner burn could certainly affect or exacerbate an existing problem, but maybe i just misstated the question to begin with. i realize that a cleaner burn can't really make the mixture more "lean," but a cleaner burn could reduce the cooling effect of a less thorough and therefore richer burn. this could also make the timing want to be in a different place, sure.

Yep I was thinking that you went to an electronic ignition and changed the plate.  With the new 3 ohm coils you have probably made a change that has impacted the temperature of the plug.  The porcelain is burning off most deposits now.  Down where the porcelain meets the metal body of the plug, the temp is cooler however and this is where you should still see a soot ring.  After a WOT chop with new plugs (maybe even 2-3 if you don't spend too much time idling) , if you have no evidence of a soot ring then you are probably lean.  Seeing it is hard but it can be done with a flashlight and a magnifying glass.  You can also shove in a different plug, ride home and grind of the metal threaded portion to really take a good look. ;)

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Re: new DYNA coils: running lean?
« Reply #16 on: June 30, 2007, 09:38:01 AM »
I have been following this and I have read the sources.  One thing you are never going to get is a direct answer for every circumstance. With these sources, you cant follow every last thing they say. That never works, but they offer good ideas on things to look for. I guess I didn't find anything confusing or contradictory when keeping all this in mind. It is a source of ideas. You are not going to find the  end-all-be-all resource. Not going to happen as every engine if a bit different. That dans mc spark plug guide, Bunch of BS. It was done in the 70s and spark plugs were different and the biggest factor of all, gas, was different. SO that little page has virtually NO application except maybe in the extreme ranges. It means even less if using the dyna.   WHat you do is take the ideas those articles eurban posted, and test them out and find what works best for you.

With the dyna, I am convinced the insulator tip should be clean and there should be a soot ring around the base.  Why? Because with what I have experienced so far show that is accurate. I run rich and I have soot about half way up the insulator. Ileaned my mix about 1/8 turn and will run that a bit. Then see what happens. It is all about small changes.

I will say that upon thinking about all this, the best time to tune is when the weather is cool. My reasoning is this, Cool air is dense and will make the bike run leaner but this is ok since the cool air also cools the engine better. As it warms up, air density is less and so the mix becomes gradually richer which helps offset the decrease in cooling from the warmer air. Once it is hot out, the rich mix helps offset the lack of cooling.

Offline HondaMan

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Re: new DYNA coils: running lean?
« Reply #17 on: June 30, 2007, 10:26:33 AM »
If you want to read plugs like a drag racer with a liquid cooled motor, you'd better do it on a 110 degree day, with a tailwind, low-to-no humidity, below sea level, with a deep high pressure area firmly entrenched throughout your test period.  Then realize that at all other times, your plugs ought to look on the rich side.

 Because the SOHC4 engine is actually overcooled by the fins in all but the most extreme conditions, the base ring will always be black/sooty.  The engine head and thread base must keep well below combustion temperatures to maintain a significant heat draw from the combustion chamber.  However, you will need temperatures sufficient for the plugs to self clean. The center insulator porcelain near the electrode tip should be near white.  Graduate to tan as you look down into the plug body, then dark brown and black near the bottom where the cylinder head maintains a temperature below that of combustion.  This is what a plug should look like after 500 miles in varying conditions.  New plugs on a brief plug chop run will begin to show this deposit pattern, but it will not be as developed as one with 500 miles of varying conditions.

...perfectly put, TT...  ;)

Installing new coils, or new ignitions, doesn't change the fuel mixture. What it CAN do is burn the mix you had a little better. This will translate, in our SOHC4/1970s twins/ to a whiter plug. Not to worry: your car looks like this, too, likely due to the 40,000+ volts found in modern ignitions. You must drive a long way to get a good plug reading.

Power dip in the lower ranges in Paulages' situation (and sequence of events) is not uncommon. What's likely happened is that the unburned fuel that once remained in the cylinders, following the exhaust stroke, before, is now gone, due to the improved efficiency of the "waste spark" cycle. This causes, effectively, a leaning in the low midrange that is due to the scavenging of the low backpressure pipe and the improved waste spark.

Paulages: you might try this: richen the idle circuit mixture, with the screw(s). Stay with the #7 plug for now. Back off the ignition timing slightly, like 1-2 degrees overall. See if this doesn't darken your plugs and improve that flat spot. If it does, then cut off 1/2 turn of the spark advancer's springs and reinstall, then put your advance back up the 1-2 degrees. That should help. This will "shift" the burning during the waste spark cycle to come on a little later in the RPM range, where, if it moves the lean-ish spot up, can then be adjusted by using the needles in the slides (up a notch).

I hope that makes sense to you: I'm typing fast, gotta go....
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Offline paulages

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Re: new DYNA coils: running lean?
« Reply #18 on: June 30, 2007, 09:33:49 PM »
If you want to read plugs like a drag racer with a liquid cooled motor, you'd better do it on a 110 degree day, with a tailwind, low-to-no humidity, below sea level, with a deep high pressure area firmly entrenched throughout your test period.  Then realize that at all other times, your plugs ought to look on the rich side.

 Because the SOHC4 engine is actually overcooled by the fins in all but the most extreme conditions, the base ring will always be black/sooty.  The engine head and thread base must keep well below combustion temperatures to maintain a significant heat draw from the combustion chamber.  However, you will need temperatures sufficient for the plugs to self clean. The center insulator porcelain near the electrode tip should be near white.  Graduate to tan as you look down into the plug body, then dark brown and black near the bottom where the cylinder head maintains a temperature below that of combustion.  This is what a plug should look like after 500 miles in varying conditions.  New plugs on a brief plug chop run will begin to show this deposit pattern, but it will not be as developed as one with 500 miles of varying conditions.

...perfectly put, TT...  ;)

Installing new coils, or new ignitions, doesn't change the fuel mixture. What it CAN do is burn the mix you had a little better. This will translate, in our SOHC4/1970s twins/ to a whiter plug. Not to worry: your car looks like this, too, likely due to the 40,000+ volts found in modern ignitions. You must drive a long way to get a good plug reading.

Power dip in the lower ranges in Paulages' situation (and sequence of events) is not uncommon. What's likely happened is that the unburned fuel that once remained in the cylinders, following the exhaust stroke, before, is now gone, due to the improved efficiency of the "waste spark" cycle. This causes, effectively, a leaning in the low midrange that is due to the scavenging of the low backpressure pipe and the improved waste spark.

Paulages: you might try this: richen the idle circuit mixture, with the screw(s). Stay with the #7 plug for now. Back off the ignition timing slightly, like 1-2 degrees overall. See if this doesn't darken your plugs and improve that flat spot. If it does, then cut off 1/2 turn of the spark advancer's springs and reinstall, then put your advance back up the 1-2 degrees. That should help. This will "shift" the burning during the waste spark cycle to come on a little later in the RPM range, where, if it moves the lean-ish spot up, can then be adjusted by using the needles in the slides (up a notch).

I hope that makes sense to you: I'm typing fast, gotta go....

i'll try this stuff, mark. thanks!
paul
SOHC4 member #1050

1974 CB550 (735cc)
1976 CB550 (590cc) road racer
1973 CB750K3
1972 NORTON Commando Combat
1996 KLX650 R

Offline paulages

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Re: new DYNA coils: running lean?
« Reply #19 on: July 01, 2007, 02:59:58 PM »
three cheers to hondaman! well, at least there's an improvement...

i played with the idle mixtures and found that 1/4 turn richer really brought the low end back a bit, and returned the off-idle response to being nice and snappy. then, i backed the ignition off just a hair, and it definitely gave a noticeable boost. when i went into second pulling away, the front end lifted a bit.  :o it'll only do that on me at the exact right RPM and gear change, but it definitely wouldn't do it yesterday.

i'll recheck the plugs when i get time and see if there's a noticeable change.
paul
SOHC4 member #1050

1974 CB550 (735cc)
1976 CB550 (590cc) road racer
1973 CB750K3
1972 NORTON Commando Combat
1996 KLX650 R