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Author Topic: Ignition, Coils & Plugs FAQ  (Read 41777 times)

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Offline Harry

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Ignition, Coils & Plugs FAQ
« on: April 08, 2005, 01:38:10 am »
I’m stuck at the side of the road (with internet access!) – how do I check my timing?
Paper method: Set the first set of points (the set attached to the points plate, not the adjustable one) so that when they're open the gap is twelve to fourteen thousandths. I then insert a piece of paper between the points while they are closed. With the bike on the center stand and the transmission in top gear, I rotate the tire to turn the engine and when it's at the 'F', I rotate the points plate so that I can just fee the pressure on the paper slack so that I can easily pull out the paper. I then put the paper between the other points, rotate the back wheel so that the other mark (isn't it 'TF'? It's been a long time!) and set them to start to open (again by a tug on the paper). Assuming that everything was set properly before, you're done. And you check everything by checking the gap on the second set of points. I'm usually pretty close on the first set of points, but the second set always needs further adjustment. The error seems to be consistently on the side of too much advance.

Spark method: Remove #4 spark plug, hook it into plug lead and balance the tip against engine ( you probably did this when checking that yellow spark ). With ignition on and switch in the "run" position rotate the crankshaft until the 1&4 "F" mark begins to appear in the window. Rotate crankshaft veeeerrrrryyy slowly until spark jumps on your plug. The timing mark and "F' line should be lined up. If not then turn plate ( clockwise will move the timing mark to the left in relation to the "F" mark, or is it right? Trial and error ).Then pull #3 plug and repeat process. Battery drains quickly when doing this so make sure you got that charger.

“Ear” method: Now when we increase the spark advance (the point when the ignition spark occurs, at the sparkplug, before-top-dead-center of the compression stroke [BTDC] ) we get more power BUT we also get more heat. There is a point after which we get lots more heat and very little extra power. We want to STOP before we get to this point! The drill is this...With the engine at normal operating temperature and idling, advance the timing slowly. You will hear the engine speed up. Move the timing back and forth, advancing and retarding it till you get the highest engine idling speed. Then back it off (retard it) just a bit. The engine speed slows down just a little. You are still idling, don't touch the throttle

So, what is “advanced” timing?
Through testing that angle turns out to be between 15 and 20° after top dead centre (TDC). Any earlier (advanced) than that and there's either too much power lost to rising cylinder pressure before TDC, or a risk of knock. Any later (retarded) than that the pressure front chases the piston down the bore rather than forcing it down. A "flat" engine sound is a symptom of retarded running.Advancing the ignition timing by 10° increases the plug tip temperature by approx. 70°-100°C. If you increase the point gap, it will retard the timing. Retarding the exhaust cam timing, some of the inert exhaust gas is left in the cylinder for the next intake stroke. This results in a cooler burn in the combustion chamber. >Advance=>rich >Retard=>lean. Knocking can be reduced by retarding timing. I find that as my point gap wears that 2&3 run lean and 1&4 run rich because the timing on 2&3 advances and the timing on 1&4 retards as the points wear.

Help! There is no more adjustment room on my adjuster plate, what do I do?
The gap in the points will affect the timing at F'. If you've run out of room on adjuster plate I would try re-gapping the points. Try a greater gap (.017) and see how this affects. When is the plug firing? I've only timed my bike once without a timing light. The method I was shown was to pull #4 plug, re-attach it to plug lead and ground tip of plug against the engine cooling fin, Then slowly rotate engine until plug sparks. note position on timing plate and adjust. When I did this I noticed that the plug firing did not correspond exactly with the point opening. Hope this helps.

How should I read my plugs, and what do the numbers mean?
The "temperature" rating (eg: hotter/colder plug) is the plug tip temperature, not the conditions the plug is used in. A hotter plug is one which has LESS heat transfer (longer nose) meaning that when used in a normal engine the tip glows hotter giving a cleaner burn with less sooting up / oil contamination. A colder plug is the opposite and is usually used by the racers. This has a short nose and the heat generated by high compression is dissipated away easily to the head. Run one of these plugs on a normal street engine and it may suffer from blackening leading to eventual misfires.

NGK BP7ES, Bosch W6DC and Champion N8Y are colder plugs.
NGK BP6ES, Bosch W7DC and Champion N9Y have same "heat value".
NGK BP5ES, Bosch W8DC and Champion N10Y are hotter plugs.

BPR5ES  -11
Thread diameter
A = 18mm
B = 14mm
C = 10mm
D = 12mm
BC = 14mm with 16mm hexagon
   
P = Projected insulator nose
U = Surface or semi-surface discharge
R = Resistor
 
Heat Range
2 = Hot 3
12 = Cold
   
Thread reach
E = 19.0mm
H = 12.7mm
   
S = Copper core
Y = V-grooved with extra projection
V = Gold/palladium centre electrode
K = 2 ground electrodes
T = 3 ground electrodes
Q = 4 ground electrodes
C = Short ground electrode
P = Platinum tip
F = Taper seat

Spark gap
-9 = 0.9mm
-11 = 1.1mm
-13 = 1.3mm

-L = Half heat range
-N = Special ground
 

A white coloured plug is caused by engine overheating. Failure to repair this engine will result in severe engine damage. Common causes for this are:
Incorrect spark plug (too hot heat range).
Low octane fuel.
Timing is not set properly.
Cooling problems, (dirty cylinder fins, no or low water if water cooled, low or no engine oil).
Carburettor air/fuel mixture is too lean (too much air).
Leaking crankshaft seals, no oil, base or head gasket leaks, or crankcase leaks on two stroke engines.



« Last Edit: March 13, 2009, 01:13:25 am by SteveD CB500F »
Harry Teicher, member #3,  Denmark....no, NOT the capital of Sweden.

Ibsen

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Re: Ignition & plugs FAQ
« Reply #1 on: April 08, 2005, 06:58:48 am »
More power to the coils and a brighter spark.

On the models with a points ignition system, the spark on the spark plugs can be improved by feeding the coils with power directly from the battery via an 30 Amp auto light relay (you can also use a double relay with one power wire to each coil). That makes it possible do increase the diamter on the power wires to the coil, and there will be no power loss.
The set up is easy:

« Last Edit: April 08, 2005, 07:01:06 am by Ibsen »

Offline SteveD CB500F

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Reading Plugs (with pictures)
« Reply #2 on: May 05, 2005, 05:25:15 am »
« Last Edit: May 05, 2005, 07:26:56 am by SteveD CB500F »
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Offline SteveD CB500F

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Spark Tester
« Reply #3 on: May 12, 2005, 05:19:21 am »
Test the veracity of your ignition

http://tools.batauto.com/index.php?crn=84&rn=827&action=show_detail (spark tester - thanks Merc2dogs)
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Offline SteveD CB500F

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Coils - What They Do and How To Test Them (thanks TwoTired)
« Reply #4 on: May 17, 2005, 05:12:09 am »
Primary connections are black to yellow or black to blue. 
The stock coils measure about 5 ohms. 
There are replacement coils available in 5 ohm and  3 ohm primaries.  This will give you a higher voltage/hotter spark.  But, they also draw more current and decrease the life of the contact points.
The secondary of the SOHC coils are from ignition lead to ignition lead as two plugs fire at the same time.  The resistance between secondaries should be about 15K ohms.  Note that the spark plug boots/caps are supposed to have resistors in them.  So, for checking the coils, unscrew the caps from the wires.

Sparking at the points is somewhat normal and not normally a concern by itself.  However, the sparking can cause the points to pit and/or carbon up.  So, the points are considered expendable and replaced during a normal tuneup of the bike.  Experience tells when to they need to be replaced.. But, if you look at new set for comparison, you ought to be able to make a reasonable judgement.  If the old points have very high peaks and valley burned into them, then replace the condensers as well.

The Honda SOHC4 ignition coil is just a simple transformer.

If that doesn’t mean anything to you, then understand that this one is a device that changes low voltage from the battery to high voltage for the spark plugs.

The coil has “gazinta” connections and “gozouta” connections. 12v is applied to the small “gazinta” wires. And, the spark plugs connect to the bigger “gozouta” wires.

With a multimeter set to measure continuity, the two “gazinta” wires should have continuity between the center conductor of the wires.
With a multimeter set to measure continuity, the two “gozouta” wires should have continuity between the center conductor of the wires.
With a multimeter set to measure continuity, any “gazinta” wire should NOT have continuity to any “gozouta” wire.
With a multimeter set to measure OHMs, the two “gazinta” wires should have about 5 ohms resistance between them, give or take an OHM.
Ideally, the “gozouta” wires should have the plug caps unscrewed and removed from the ends for the above tests.

Functional test.

If your spark plug boots are still installed, insert a spark plug in each one and arrange them so that the threads of each plug are touching the other. Each time you apply and disconnect 12v to the “gazinta” wires, both spark plugs should display a visible arc between the center electrode and the plug body electrode.

If your spark plug boots are removed, arrange the “gozouta” wires so that their ends are about 1/8 inch apart. Each time you apply and disconnect 12v to the “gazinta” wires, there should be a visible arc between the “gozouta” wires.

It is best to keep personal anatomy inventory well away from the “gozouta” vicinity during the functional test.
The coils believe you are a conductor, regardless of whether or not you have lead an orchestra, or handled tickets on a train, and will deliver a strong message to you if you provide the opportunity.

The 12v source should have a current capability of at least one amp.
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Offline SteveD CB500F

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Fitting Accel cables to stock coils (Thanks Polishbeer)
« Reply #5 on: July 23, 2005, 02:54:27 am »
Early Honda coils had fixed spark plug cables yes? Well they're still inductive, and the cables will be the first to go with age, corrosion and cracking.  I could literally HEAR my 1 and 2 cylinder cables shorting out on the engine when the bike got to operating temperature, and the bike ran terribly.  So, I deduced that if I were to simply CUT OFF the cables at the coils flush, and drill them with approximately a slightly undersize 7.5mm bit (approximately .218") nice and square, I could SHOVE brand new 8.5mm Accel graphite-impregnated core cables in them and reuse the spark plug connections since they have a stud center, and simply screw them on.
I knew the connectors weren't the culprit since they're so heavily constructed, but the cables themselves looked like junk so they had to go. 
Now I have beautiful NEW Accel cables and original coils and connectors, and the bike runs great.  If you think about how much new dual-post Accel brand coils and cables cost, I saved about $140.00 x 2, and it works. 
By the way you can only drill about half an inch into the coils and still get a connection, so you'll have to epoxy the cables into the coils once they're shoved in, which works fine and is an invisible fix.

The beautiful part of this is that an Accel $40.00 UNIVERSAL set of cables for an American V8 car has enough cable length to do this fix to about six SOHC fours.  HUGE man, that's HUGE!


I got this idea from my mechanic friend Dr. John, who specializes in Honda SOHC fours.


(Thanks to polishbeer)
« Last Edit: August 26, 2005, 10:37:19 am by SteveD CB500F »
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Offline SteveD CB500F

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Optimizing the Standard SOHC4 Ignition System
« Reply #6 on: August 25, 2005, 12:06:52 pm »
Go here:

http://www.motorcycleproject.com/text/sohcign.html

EDIT: Broken link fixed. Thanks to "knottedknickers" for the info. Steve.
« Last Edit: July 28, 2015, 07:36:54 am by SteveD CB500F »
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Offline TwoTired

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Running out of timing adjustment range with points plate
« Reply #7 on: November 30, 2005, 10:09:52 pm »
If you remove the points from the plates and loosen all three large plate mounting screws, you will find that that large plate will move some distance radially on the mount posts machined into the engine case.  This movement is why you run out of adjustment range, as some plates are different diameters, and some engines have been machined to a different tollerance limit.  The spring pressures of the points pushes the plate in the opposite direction against the mount post. This puts both points in a position relative to where adjustment range is limited.
What to do.  While you have the points removed from the plate (thus all spring tension) and all three mount screws lossened, find the largest feeler gauge that will insert in the gap between mount post and large breaker plate. This is also the point gap error and directly impacts timing.  Reinstall the 1-4 points, set the gap and the 1-4 static time with the feeler gauge still inserted in the lower right mount post to breaker plate gap.  I sacrificed a feeler blade and cut one in an L shape to fit under the mount screw washer, so it wouldn't fall out during plate rotation. This way I can change the 1-4 timing while the bike is running (dynamic timing) or not (static timing).  In my experience, this brought the adjustment slot for both 1-4 and 2-3 points into an acceptable adjustment range.
How did I figure this out?  Well, the bike showed me this problem.  One day, while trying to dynamically time the engine, I had all three mountplate screws loosend while the engine was running.  It was then I could see the whole friggin plate moving around in the engine posts.  Dwell readings were all over the place, too, depending on which mount screw I tightened first or when and where the engine crankshaft was positioned when a mount screw was tighened.  Putting the plate in a stable position eliminated all the variability of time and dwell.  Then I found that if selected the right post to remove the excessive plate movement, the adjustment ranges of the slots were more than adequate.  So, I made a new tool, and, added it's use during the adjustment procedure.
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Offline SteveD CB500F

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Can I use 1.5/2/3/5 ohm Coils and what difference will it make?
« Reply #8 on: March 13, 2009, 01:12:34 am »
From Two Tired:

You can use 3 ohm coils.  But, you better plan on keeping the engine above 3000 RPM 75% of the time.  Otherwise, get 5 ohm coils for a street bike.  Your alternator only puts out 150 Watts at 5000 RPM and about 40-50 Watts at idle.

3 ohm coils will draw 55 watts with point ignition and about 50% more than that with a Dyna-S ignition (if the reports I've seen of it's operation are correct).  5 ohm coils (such as Stock) draw about 33 W. The stock bike normally needs about 100-110 watts without ignition or lighting mods.
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Offline SteveD CB500F

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Replacing Plug Leads / Wires
« Reply #9 on: March 13, 2009, 05:34:49 am »
See attachment
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;
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