Author Topic: Weak ignition?  (Read 2552 times)

0 Members and 2 Guests are viewing this topic.

Offline Dunk

  • Expert
  • ****
  • Posts: 932
Weak ignition?
« on: December 29, 2015, 06:45:15 PM »
Thought these plugs were interesting. I've been through the carbs a couple times. Had a set of bad slow jets initially which several were obstructed. Have cleaned and checked float level each time I've had them apart. This bike initially ran like crap when cold with the smaller than advertised slow jets. After swapping to jets that seemed consistent in size across a few sets it runs better.

Just put a Dyna S on it and had the plugs out to put the nipple on them. #4 looks rich, #1 maybe slightly lean... And 2-3 look almost new. My mind is on ignition currently, but I wonder if the 2-3 coil was weak making plugs appear as they do? Points were cleaned, gapped, and timing set dead on each set. With the Dyna, 3 ohm coils, and new copper core wires it starts easier and runs better cold. Just took choke for a couple seconds then idled a little low/rough and smoothed out quick as I set timing. Much better cold idle. It's cold and wet out so no test ride, but I expect it to run much better. Is this likely ignition? Should I revisit carbs? Thoughts?


Offline Taelonorigin

  • Full Member
  • *
  • Posts: 24
Re: Weak ignition?
« Reply #1 on: December 29, 2015, 08:34:03 PM »
Are those at idle or a plug chop? Also, how did you test the jets?

Online HondaMan

  • Someone took this pic of me before I became a
  • Really Old Timer ...
  • *******
  • Posts: 13,894
  • ...not my choice, I was nicknamed...
    • Getting 'em Back on the Road
Re: Weak ignition?
« Reply #2 on: December 29, 2015, 10:22:25 PM »
Based on your description, that looks a whole lot more like minor vacuum leak issues with the carb hoses than any ignition or carb problems. The idle jets should be #40, regardless of any external changes to the engine that may have been made. The only exception to this is: if you have installed a cam that opens before 8 degrees BTC, you may have to drop to the #38 jets to be able to make a clean idle without spitback problems that wet and slowly drown the idle.

The ignition itself will not change plug colors. This is purely a function of fuel mix. With Dyna 3 ohm coils and a Dyna S aboard, you are about to experience a whole 'nuther set of problems, though...please search a bit, as I have literally typed out this explanation at least 15 times this summer alone.

If it ran poorly with the old coils, chances are the sparkplug caps needed to be replaced, and possibly the condensors. They are resistor caps, which lengthens the spark duration on purpose, to ignite a wider flamefront in these swirl-charged engines. The Dyna coils have a very short spark, and the Dyna S makes this even worse, weakening this fuel-ignition process. So, at the very least you need resistor sparkplug caps, resistor plugs, and larger plug gaps to start to balance out those issues. The clue here: good points, coils, and plug caps make these bikes start at the touch of the Start button, if the carbs are set correctly. All else being equal, this will NOT happen when the Dyna S is added to that situation: instead it takes a bit more choke and warmup time for them to settle into a smooth idle, due to their very short spark. So, if yours got better by adding the Dyna stuff, then the old plug caps were likely toast, for starters. I "see" this sort of thing happen here a lot, only to then watch the ensuing low-battery problems showing up in the next riding season.... ;)

I make a Resistor Pack that will partially help with the situation you now have: I'd recommend it in a 2-ohm value lest you end up with a chronically low battery and heavily-loaded Dyna S triggers. Then, get some resistor-type plug caps (the normal ones are #VD05F for 1-4 and #SD05F for 2-3, from places like PartsNmore), strongly consider some resistor-type sparkplugs to go with that, and open the gaps on the plugs to about 0.032"-0.038". These things, added together, will stabilize the spark over the whole RPM range while extending the discharge a little more, and will help cool off the coils, Dyna S triggers, and the alternator.

Oh - and the carb boots: even if the old aluminum-strap clamps are tightened to their living end, if the rubber is now hard (from years and heat) it will not seal at the head end. You can replace them, or try to get a little more life from them with some of the Oettiker clamps, but if you use those be careful to not tighten them so much it splits the (now) plastic-like rubber boots! I've done that... :(
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

Link to website: www.SOHC4shop.com

Offline Dunk

  • Expert
  • ****
  • Posts: 932
Re: Weak ignition?
« Reply #3 on: December 30, 2015, 07:03:37 AM »
I guess I should have provided more background... It's a stock CB750 K5 with a 4 into 1 pipe. I have not rode the bike for a month (rain, cold, life, etc.). Bike is new to me as of Sept/Oct. Conditions just prior to last shutdown were likely fully warmed up engine having romped around town, idle a few seconds up the driveway then shut down. Plugs have a few hundred miles on them. Not exactly scientific, just thought the very clean looking 2-3 plugs were odd, as if not firing consistently and getting washed down with fuel or possibly just lean.

It could be vacuum leaks, though boots are soft and new(er) from PO. One of the clamps was too large and I swapped for a smaller one that tightens properly. I will spray around the boots just to be sure though.

I have had 3 sets of idle jets stamped 40 in these carbs. The first was way lean at idle, the second was way rich... At that point I started eyeballing them closer and noticed the first set that came in the carbs while appearing brand new appeared to have a very small hole. The second set came off a rack on a pretty hot engine that ran well with 140 jets. These looked very large, and as it turns out were drilled. No good for a stock K5 engine. Compared a couple other sets of slow jets from other racks and found the rest to appear consistent in size so cleaned up a set and threw them in, now it starts easier cold and idles better, and mixture screws have some effect where before they had little/no effect.

Regarding the Dyna. I seem to recall measuring the old spark plug caps at around 9k-10k ohms. I will measure them today or tomorrow for some postmortem. I do have new caps, I think one set is resistor and another is non resistor. The plugs I am running are NGK DR8EIX, iridium with 5k resistor. I have runs these plugs with a Dyna S, 3 ohm coils, and solid wires with no resistor caps on 4 CB750s now and never had a problem with insufficient charging or dead battery. Noteworthy items may be that I rarely use the electric start (though it always works when I do) and I don't have any other additional electric loads. Also, this bike is a K5, the other bikes I've used this setup on have been K1 and K2, not sure if the later bikes had any charging system differences which could result in problems?

I'm content to run it as is since it has worked for me... If there are charging issues I can add the 2 ohm resistor pack you offer. Is the 5k ohms in the plugs themselves sufficient or should I be adding resistor caps as well? If so what total resistance would work best? Also I will check voltage at idle and various RPM to assess charging.

Online HondaMan

  • Someone took this pic of me before I became a
  • Really Old Timer ...
  • *******
  • Posts: 13,894
  • ...not my choice, I was nicknamed...
    • Getting 'em Back on the Road
Re: Weak ignition?
« Reply #4 on: December 30, 2015, 06:16:13 PM »
I guess I should have provided more background... It's a stock CB750 K5 with a 4 into 1 pipe. I have not rode the bike for a month (rain, cold, life, etc.). Bike is new to me as of Sept/Oct. Conditions just prior to last shutdown were likely fully warmed up engine having romped around town, idle a few seconds up the driveway then shut down. Plugs have a few hundred miles on them. Not exactly scientific, just thought the very clean looking 2-3 plugs were odd, as if not firing consistently and getting washed down with fuel or possibly just lean.

It could be vacuum leaks, though boots are soft and new(er) from PO. One of the clamps was too large and I swapped for a smaller one that tightens properly. I will spray around the boots just to be sure though.

I have had 3 sets of idle jets stamped 40 in these carbs. The first was way lean at idle, the second was way rich... At that point I started eyeballing them closer and noticed the first set that came in the carbs while appearing brand new appeared to have a very small hole. The second set came off a rack on a pretty hot engine that ran well with 140 jets. These looked very large, and as it turns out were drilled. No good for a stock K5 engine. Compared a couple other sets of slow jets from other racks and found the rest to appear consistent in size so cleaned up a set and threw them in, now it starts easier cold and idles better, and mixture screws have some effect where before they had little/no effect.

Regarding the Dyna. I seem to recall measuring the old spark plug caps at around 9k-10k ohms. I will measure them today or tomorrow for some postmortem. I do have new caps, I think one set is resistor and another is non resistor. The plugs I am running are NGK DR8EIX, iridium with 5k resistor. I have runs these plugs with a Dyna S, 3 ohm coils, and solid wires with no resistor caps on 4 CB750s now and never had a problem with insufficient charging or dead battery. Noteworthy items may be that I rarely use the electric start (though it always works when I do) and I don't have any other additional electric loads. Also, this bike is a K5, the other bikes I've used this setup on have been K1 and K2, not sure if the later bikes had any charging system differences which could result in problems?

I'm content to run it as is since it has worked for me... If there are charging issues I can add the 2 ohm resistor pack you offer. Is the 5k ohms in the plugs themselves sufficient or should I be adding resistor caps as well? If so what total resistance would work best? Also I will check voltage at idle and various RPM to assess charging.

OK, that helps a little bit!
The post-1973 750 bikes produce a little bit more power because their alternator rotors were more precisely made. The advertised wattage has always been 210w, but most make about 160-180 when hot.

Might it be: the dark sparkplug came from the cylinder with the incorrect clamp?

The resistance situation: the OEM plug caps on the K4/5 bikes were 7500 ohms, and are considered burned out if either the resistance on the 2 of one coil are different by more than 500 ohms, or if they are above 8500 ohms. They get higher in resistance as they age, because the little carbon pellet burns off a bit at a time, burning the contacts inside as it does. This is entirely normal. Today we can get 0 ohm, 5000 ohm, and 10,000 ohm caps (although the latter are hard to find, for some reason). The "05" in the numbers I cited above are the "5K" value (5000), while the other parts numbers have either "00" or "10" in those 2 digits, for 0 ohms or 10k ohms, respectively.

Here's the story behind the resistance: as the coil discharges its spark, the amount of current that passes during the spark determines how fast the discharge occurs. Inserting resistance in the path makes the spark last longer. For example, using the numbers I measured during the  development of the Transistor Ignition (here in these forums), the discharge time of the OEM coils with 0 ohms was about 1.05mS at 5000 RPM, 1.45mS with 5000 ohm plug caps, and 1.70mS with 10,000 ohm plug caps. It looks from this data that Honda "split the difference" between the 5k and 10k values, as the shorter increase between 5k and 10k vs. the 0 ohms and 5k values shows the coils were maxing out somewhere between those 2 upper values. (This has to do with how much inductance was wound into the particular TOYO coils that they used.) Today, we can approximate the 7500 ohm 'nirvana' value by using the 5000 ohm caps and the typical resistor sparkplugs, most of which are in the 2000-ohm range (a few are higher, usually intended for EFI closed-loop automotive systems that vary spark and fuel via software, in real time).

When the coil inductance gets lower (i.e., 3-ohm coils) the resistance must get higher to prolong the spark discharge. In these engines, unless you build them past 10.5:1 compression, they only need 4500 volts to spark sufficiently to run well, cold or hot. The OEM coils make about 7500 volts at 12 volts power (most get only 11.0 volts, making about 6000 volt sparks in the process), so their excess capability is almost 80%. The Dyna 3-ohm coils make 30kV at 5000 RPM into a 0.050" gap, but the discharge is a pitiful 0.9mS long (i.e., less than 1mS). In addition, the Dyna S triggers short-circuit the last 40% of this spark above 5500 RPM, on every firing, because they switch back on too soon, interrupting the spark and heating the coils.

This, specifically, was why they often burned themselves out when run in high-speed touring in the "old days" when we ran back-to-back-to-back 1000 mile days for sometimes 2 weeks at a time. I burned out 2 coils (1 in each pair) and 2 Dyna S units (one of those running OEM coils) in 3 years, and quit using them afterwards. I hate pushing my bike...oh- and also a Dyna III unit, which was Dyna's first answer to the 'too-short dwell' question, circa 1974. This little box went between the Dyna S and the coils, stretching the OFF time a little bit in the process, to cool off the coils. But, the boxes frequently died on the hiways, and I haven't even seen a working one in 20 years(!). At least at the time we could unplug it and run from the Dyna S triggers to get home! :)

To cool of the "hot" coils today, and improve the engine performance at the same time, here's the tips:
1. Use resistor caps AND resistor plugs. This also helps to stretch the discharge time, attaining nearly 1.15mS if the caps are 5000 ohms and the plugs are 2500 ohms. If you can find the 10k plug caps, go for it! You might reach 1.2mS, which you will notice at speeds above 60 MPH.
2. Make sure the gaps on the Dyna triggers (between the pickups and the magnet) are exactly equal, and in the midrange where they work. This takes some time to set up: with the engine warmed up, first move the pickups (one at a time is OK) away from the magnet until it won't fire, then repeat TOWARD the magnet. Measure each position with a feeler gage, add those together, divide by 2, and set them at that distance. THEN time them, using a strobe timing light. This will provide the longest-possible OFF dwell time at the full RPM range, with it running longer at low speeds and getting shorter at high RPM, particularly above 5500 RPM.
3. When you're ready, get a Resistor Pack. This will simultaneously cool off the coils, the triggers, extend the spark another 0.5mS, and lighten the load on the alternator, Run-Off switch, and keyswitch wiring. This will let the system voltage rise, which in turn will improve the spark, particularly in heavy city traffic after 2 hours of riding time (typically).

Happy New Year! Stay warm.
-HM
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

Link to website: www.SOHC4shop.com

Offline RevDoc

  • Hot Shot
  • ***
  • Posts: 556
Re: Weak ignition?
« Reply #5 on: December 30, 2015, 08:48:24 PM »
As always, Mark, the depth of your knowledge & command of the tech details on these systems is astounding! I'm sure I speak for many others when I say Thank You for being so gracious in your sharing!
Dana

'78 CB550K--Angie
'82 CB750 Custom--Eva



As soon as you straddle a bike expect every other driver on the road to suddenly start competeing for the title "Dumbestsonofa#$%*inallNorthAmerica!!"

Offline stikman

  • Bit of an
  • Enthusiast
  • **
  • Posts: 189
Re: Weak ignition?
« Reply #6 on: December 31, 2015, 07:33:44 AM »
As always, Mark, the depth of your knowledge & command of the tech details on these systems is astounding! I'm sure I speak for many others when I say Thank You for being so gracious in your sharing!

^ This
1977 CB750A "High Horse": 836cc, mild porting, custom cam, K5 roundtops, v-stacks...
1973 CB750K D5 plunger frame chopper currently building..

Offline Dunk

  • Expert
  • ****
  • Posts: 932
Re: Weak ignition?
« Reply #7 on: December 31, 2015, 11:37:02 AM »
Thanks, a wealth of knowledge. If plugs have 5k ohms as advertised the 5k caps I have should get me to that ideal 10k for longest spark duration. Thanks for the detailed explanation. I did have to adjust one a few degrees to get timing the same on each coil but didn't check the gap. I'll take the time to get the Dyna pickups adjusted to ideal.

I measured the caps that came off the bike:
1: 13.25k
2: infinite or >2000k
3: infinite or >2000k
4: 14k

Think that explains the middle plugs?

Online HondaMan

  • Someone took this pic of me before I became a
  • Really Old Timer ...
  • *******
  • Posts: 13,894
  • ...not my choice, I was nicknamed...
    • Getting 'em Back on the Road
Re: Weak ignition?
« Reply #8 on: January 03, 2016, 07:07:44 PM »
As always, Mark, the depth of your knowledge & command of the tech details on these systems is astounding! I'm sure I speak for many others when I say Thank You for being so gracious in your sharing!
Always glad to help!
I'm one of those [rare?] people who think knowledge is worth the most when it is shared. :)
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

Link to website: www.SOHC4shop.com

Online HondaMan

  • Someone took this pic of me before I became a
  • Really Old Timer ...
  • *******
  • Posts: 13,894
  • ...not my choice, I was nicknamed...
    • Getting 'em Back on the Road
Re: Weak ignition?
« Reply #9 on: January 03, 2016, 07:08:48 PM »

I measured the caps that came off the bike:
1: 13.25k
2: infinite or >2000k
3: infinite or >2000k
4: 14k

Think that explains the middle plugs?

Oh, yeah...right on the dot!
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

Link to website: www.SOHC4shop.com

Offline BasicPoke

  • Full Member
  • *
  • Posts: 32
Re: Weak ignition?
« Reply #10 on: November 26, 2020, 10:20:25 PM »

I measured the caps that came off the bike:
1: 13.25k
2: infinite or >2000k
3: infinite or >2000k
4: 14k

Think that explains the middle plugs?

Oh, yeah...right on the dot!

Can someone please explain how an open-circuit plug cap causes the plugs to be very clean.
« Last Edit: November 27, 2020, 06:10:21 PM by BasicPoke »

Online HondaMan

  • Someone took this pic of me before I became a
  • Really Old Timer ...
  • *******
  • Posts: 13,894
  • ...not my choice, I was nicknamed...
    • Getting 'em Back on the Road
Re: Weak ignition?
« Reply #11 on: November 27, 2020, 06:53:53 PM »

I measured the caps that came off the bike:
1: 13.25k
2: infinite or >2000k
3: infinite or >2000k
4: 14k

Think that explains the middle plugs?

Oh, yeah...right on the dot!

Can someone please explain how an open-circuit plug cap causes the plugs to be very clean.
Sure: weak spark on those plugs means the gasoline is always washing those plugs clean more often than they are firing. It's wet firing that makes them dirty. It's sort of like when you put Fuel Injector Cleaner in your car's gas tank: it scrubs the plugs with solvent. All gasolines today have detergent (actually, a solvent, something like bromide or ethanol) in them to help reduce carbon buildup.
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

Link to website: www.SOHC4shop.com

Offline Deltarider

  • Really Old Timer ...
  • *******
  • Posts: 8,132
  • ... but some animals are more equal than others.
Re: Weak ignition?
« Reply #12 on: November 28, 2020, 07:37:02 AM »
Thanks, a wealth of knowledge. If plugs have 5k ohms as advertised the 5k caps I have should get me to that ideal 10k for longest spark duration. Thanks for the detailed explanation. I did have to adjust one a few degrees to get timing the same on each coil but didn't check the gap. I'll take the time to get the Dyna pickups adjusted to ideal.

I measured the caps that came off the bike:
1: 13.25k
2: infinite or >2000k
3: infinite or >2000k
4: 14k

Think that explains the middle plugs?

1) In spite of all my search efforts, I have found no substantiation for this 'longer spark' duration by increasing resistance thesis, at least not from 5kΩ to 10kΩ. Not in any automotive literature, not when consulted experts in the field. Yet I will remain modest, simply because I can't rule out such a phenomenon exists. If any such effect exists, if, I expect it to be within the noise band. At best. Which brings me to...
2) So far I have not heard/read ANY testimony of a benificial effect on the ignition in daily practice after going from 5kΩ to 10kΩ, let alone that such an effect could be reproduced in tests.
3) NGK 10kΩ plugcaps are no longer in the shops and I wonder if they're still being produced.
4) Fitting 10kΩ resistance in a dual outlet coil ignition means 20kΩ in one circuit. Personally I consider that too much. The Honda France manual is clear on this: plugcaps > 8kΩ are to be abandoned.
Adding resistor plugs to resistor caps implies a higher risk of malfunction over time as I see it.
Frankly I'm a bit tired of claims, whether they concern fuels or ignition, that seem to have one thing in common: they never can be reproduced, let alone proved.
I have said it before and I say it again: I'm with the scientist Popper who rooted out all 'religion' from science by demanding every theory, any theory to be falsifiable by... science. It's the only way to save us from assumptions based on beliefs or respect.
CB500K2-ED Excel black
"There is enough for everyone's need but not enough for anybody's greed."

Online HondaMan

  • Someone took this pic of me before I became a
  • Really Old Timer ...
  • *******
  • Posts: 13,894
  • ...not my choice, I was nicknamed...
    • Getting 'em Back on the Road
Re: Weak ignition?
« Reply #13 on: November 28, 2020, 07:00:33 PM »
Thanks, a wealth of knowledge. If plugs have 5k ohms as advertised the 5k caps I have should get me to that ideal 10k for longest spark duration. Thanks for the detailed explanation. I did have to adjust one a few degrees to get timing the same on each coil but didn't check the gap. I'll take the time to get the Dyna pickups adjusted to ideal.

I measured the caps that came off the bike:
1: 13.25k
2: infinite or >2000k
3: infinite or >2000k
4: 14k

Think that explains the middle plugs?

1) In spite of all my search efforts, I have found no substantiation for this 'longer spark' duration by increasing resistance thesis, at least not from 5kΩ to 10kΩ. Not in any automotive literature, not when consulted experts in the field. Yet I will remain modest, simply because I can't rule out such a phenomenon exists. If any such effect exists, if, I expect it to be within the noise band. At best. Which brings me to...
2) So far I have not heard/read ANY testimony of a benificial effect on the ignition in daily practice after going from 5kΩ to 10kΩ, let alone that such an effect could be reproduced in tests.
3) NGK 10kΩ plugcaps are no longer in the shops and I wonder if they're still being produced.
4) Fitting 10kΩ resistance in a dual outlet coil ignition means 20kΩ in one circuit. Personally I consider that too much. The Honda France manual is clear on this: plugcaps > 8kΩ are to be abandoned.
Adding resistor plugs to resistor caps implies a higher risk of malfunction over time as I see it.
Frankly I'm a bit tired of claims, whether they concern fuels or ignition, that seem to have one thing in common: they never can be reproduced, let alone proved.
I have said it before and I say it again: I'm with the scientist Popper who rooted out all 'religion' from science by demanding every theory, any theory to be falsifiable by... science. It's the only way to save us from assumptions based on beliefs or respect.

Do you have an oscilloscope, Delta? That will immediately prove out my 'claims'. Just hook up the scope to the tip of the plug while it runs (use a 100M ohm resistor to avoid damaging the scope's input stage), measure the spark duration, then increase the resistance and do it again. Way back when I developed the Transistor Ignition here (2006-7) I posted oscilloscope traces of the resutls, and one coil had 5k ohm caps while the other trace had 10k caps. It showed there, in the timebase on the screens.

I am an electronics end controls engineer, now over 40 years. Adding resistance to an L-R circuit WILL increase the oscillation (discharge) spark duration, and by a calulable amount. That's why I suggest using it: also, 30 years of it on my own 750 (and many others I have worked on) has proven it true. Especially noticeable here in the high country: when riding above 8500 feet altitude, the engine is much more responsive with resistor plugs aboard than when not, and it will idle at 14,000+ feet with resistor plugs in it, but not with non-resistor plugs: then it just slows down and stops when trying to park.
;)
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

Link to website: www.SOHC4shop.com