Pulse generator

Sorry if I misled you .The last time riding my bike it died completely ! Not able to limp home ,as I was able too the last couple times . It would not start again . After bringing it back home , the first thing I did was install new plugs . No change . Tried changing to known good ignition box , no change . Next tried 4 known good coils , no change . Pulled plugs , they were visibly wet & not firing . Bought & changed with 4 new plugs , no change . This is when I began looking at & testing pulse generators. Witch turned out to test bad . Also the recently purchased P\G also failed to test within specs . Now having neither set test out within specs , am I not right in assuming that I need a new set that do test out within specs . Such as yours are ? I retested new set after heating them up & they still never rose above 390 ohms . Again failing to reach the acceptable specs of 450-550 ohms . Am I wrong to feel that any readings other then between 450-550 ohms at room temp or heated up are BAD ? So far this is the only part of my bike that is verify-ably not within the stated factory specs . Again thank you for your HELP !

 

I have not had the chance to heat & retest the original P\G as they are still on my motor . Wasn't planning on removing side casing until I had in my hand a set of P\G that tested good

 

What I find hard to believe is both pulse generators to fail at the same time or was it only running on 2 cylinders and then the second P/G died?

 

I am thinking it was only running on two sporadically at first but then both failed killing the bike all together ? The bike was running fine , then started missing on one cylinder then two intermittently for a few minutes ,then suddenly run fine again . Not on every ride , but randomly . Ran fine again for a few months , just long enough for me to stop thinking about it . Then it started dropping the two cylinders together after 15 to 30 minutes of riding every time . That is when I first changed to new plugs . On next ride after about 30 - 45 minutes bike started missing on what seemed to be all 4 cylinders till it lost enough speed to just plain die . Have not been able to get engine running since .I'm just guessing that after 28 years they finally gave up ? Is it not at all possible that maybe they tend to fail soon one after the other ? The other set I just got both have very close low readings . Believe me I am totally in the dark about all this . But I do think until I get a set that test out within the 450-550 ohms specs , I'm not going to cure the problem ?

 

Let me say that changing parts willy nilly is not the proper procedure to go through, but I won't dwell on that.

So it sounds like we have a tough situation here. When you find yourself pulling your hair out trying to diagnose its best to start from the beginning with a clean slate and go step by step.

Motors need 3 things to run, fuel, compression and spark. We seem to be certain that it's getting fuel, hopefully not too much flooding the engine.

It's doubtful a running engine would loose compression, but you could pull the plugs and measure, just to be sure. Something mechanically breaking in the engine is possible, but not likely.

Then we get to the ignition. A basic test for spark is to pull a plug wire and put an insulated screwdriver into the boot and hold the metal shaft about 1/4" from a good ground source and see if a spark jumps the gap. If so then hold the shaft a little further from the motor and try again. A healthy spark can jump 1/2" to 1" and be blue in color. If you get no spark at all, then let's see if the spark plug coils are getting full battery power with the key on. The ignition box will send a brief ground signal to the coil telling it to fire. That signal might be hard to measure. A digital meter set to beep when continuity happens might be fast enough to hear or if you use a manual meter with a needle you might see it flicker or pulse briefly on the ground signal.

I would do the spark plug test first then work your way up and let us know your results. A really weak spark would indicate one thing or a low spark plug coil voltage would lead us down a different route.

 

Jason you are right, but to have the coils fail together or the pulse coils do the same thing is very long odds but he must do the tests as you describe, except the compression test is a problem if you don't have an adaptor and I doubt very much it is a compression problem, compression on 4 cylinders do not all fail together

 

Thank you for all your input . Please ,please don't take this the wrong way ? The last thing I would ever want to do is offend any of you . Yes I am having difficulty with this problem , but I am somewhat adept with working on motor vehicles . I have compression ,fuel but little to no spark . I have checked for spark at all cylinders . # 2 & 4 no spark # 1 & 3 very weak spark as tested with a spark tester . The type you plug in plug wire & ground to block . Ignition box is a non issue as I have two verified working boxes . You guys seem to be forgetting that I have pulse generators that are not within except able specs . I don't see how I can move forward until I do . These P\G not testing out to be between 450-550 ohms proves them to be not working up to required needs ? Does it not ? If they did test correctly like on Jason's bike , I would be looking for problems else where . As to the odds of both failing together , I agree are great . But that seems to be the case on both the ones on my bike & the new ones I just purchased . As to the comments stating that if both are reading 360 ohms they should be fine as opposed to one reading 360 & the other reading 500 ohms being bad & the problem . I strongly disagree ! Any P\G that don't test between the stated specs by the factory Honda manual of 450 -550 ohms are BAD . Right ? Any & all other readings but those stated are not going to be adequate . Correct ? If not , whats the use of following the manual ? Does not the P\G 's on my bike reading 291 & 302 ohms PROVE that they have failed ? I believe they do . Please if I'm wrong or you find my way of thinking to be flawed I welcome your opinion & input ! Thank you all

 

Ok so try this, disconect the neg wire from the 2/4 coil, get a piece of wire with a connector on it, turn the ignition on and with the 2 or 4 plug out and against the motor, flick the bared end of the wire from the neg of coil onto the motor, this should give you a spark.

 

A1gatorz, your flat out wrong. Firstly, the factory service manuals do contain mistakes. It's not gospel. There is a list of all the mistakes somewhere on this forum.

Secondly, you have to follow the correct order to diagnose something properly. You could have 2 related problems that are making your bike not run. If you don't follow the steps in order you will never get it fixed. Your problem could be something simple like bad ground or a dirty connector or faulty ignition switch. So let's come back to the pickup coils later on.

So as of right now, #2 & #4 have no spark and #1 & #3 have very weak spark?

What is the voltage at each of the spark plug coils? Remember that they get battery voltage through a long chain of devices, first the main fuse, then the ignition switch, then ignition fuse, then engine kill switch then finally to the coils. So all of these switches, fuses and connectors can and do cause a voltage drop especially on an older bike. Expect 1/2 volt less than battery. This is easy and fast to check and we can then move to the next thing to test.

Let's then check the power and ground going to the ignition box. Unplug the connectors and check that the dark green has little to no resistance to ground. The black/white should have battery voltage or a tiny bit less. Then check your pulse generator wires and see what, if any, additional restance your getting.

I know you swapped spark plug coils, did you test the primary and secondary coils against the book values? Did they check out okay?

Now would also be a good time to check and clean any ground wires you see. Make sure they are getting good metal to metal contact with the frame.

If you see any connectors that are dirty, clean them the best you can and add dielectric grease to prevent corrosion coming back.

 

Okay, I see. Your saying disconnect the ignition box wire from either the 2 or 4 spark plug coil and then ground that coil connector (with the key on) to simulate a negative pulse from the ignition box and see if the plug fires. Your basically ruling out the ignition box and only testing the coil, plug and plug wire. That's a good test, but should only be done after making sure the coils are getting good voltage.

 

Jason, on the Supersport forum one of the first things that is advised with ignition problems, for exactly the reasons you have just stated. Old wiring, switches and connectors. Fitting a relay and taking power straight from the battery to the relay and using the + wire to the coil as the relay trigger wire, this way you get 12+ volts straight into the coils. Problem is you have old wires and then you try cranking the motor over and often if you check it you can have as little as 8 volts at the coils

 

My old Virago had low voltage going to the coils. I think it was a 2 volt drop from the battery. It ran well, but idled bad as the coils barely fired since voltage was lowest at idle. I had to check for voltage drop piece by piece and finally traced it to a dirty connector straight off the battery feeding the key switch. I can understand the temptation to add a relay to pump up the coil voltage, but that only fixes one thing while other voltage drops may continue to effect the bike. So, it's a good idea, but it's best to find the actual problem (in my opinion).

Then again, sometimes you need to redesign a whole circuit. The main fuse and reg/rec on our bikes is just not designed well. The main power and reg/rec spade connectors on our bikes tends to melt. I replace all that with a new main fuse holder, beefier wires and soldered connectors. I redid the rec/reg with a massive unit that barely gets warm and has oversized wires, factory sealed connectors and no spade connectors at all.

A1gatorz, another theory I had, was that maybe the bolts holding the pulse generators got loose and the gap changed and that's why your bike is not running. If it's not running at all, why not pull the cover off and take a good look inside? Why wait? You could do that heat test as well as check the wiring going through the cover. Sometimes the insulation wears down there and they can intermittently short out.

Also, if it makes you feel any better, certain Honda pulse generators did have around 330 ohms. The 85-86 Goldwings. So that;s something.

Where are all the folks with 87 bikes? Can't you guys measure your pulse generators? Just pop the cover off over the battery, unplug the coil connector and measure resistance. Not hard at all.

 

Ok , I understand where your coming from . Lets see if I got this straight . 1st I have redone all grounds on bike last year when I upgraded my reg/rec to new R1 mosfet type . I will double check them again . 2nd Yes I did test all coils , plug wires & caps to factory manual specs. All check out fine 3rd I realize possible manual misprints . But I have all three manuals ( Honda , Haynes & Clymer ) that state 450-550 ohms on P\G 's So that should rule that out ? 4th When you say ignition switch you mean the key or on\off bar switch or both ? I'll check them 5th When checking voltage to coils , does it matter witch wire I'm testing ? It appears to have 12 volts on both wires ( black\white & yellow\white - blue\ black etc. ? No negative side ? Do I check at rest & when cranking ? 6th I will check voltage and ground resistance at ignition box . All this sounds like good advise . But does any of these factors change the low ohms reading I'm getting at the P\G ? If not , am I not still facing this problem ? I am in full agreement with all that your saying if I'm understanding you right ? If all these other factors are up to par , then & only then I should consider changing the P\G's ? Whats your opinion on the low ohm readings on the new set of P\G's I just got ? Do you think I was sold wrong year ? If they were correct for my bike & in good shape shouldn't they test at spec ? I would think so ? Thanks

 

4th, I mean the key ignition switch. The other is the kill switch.

5th, only the black and white. Check with key on only and then check while cranking. You need a healthy battery to keep the voltage up above 10v to the coils while cranking. If it drops low, add a battery charger to boost the voltage up or add a car battery for testing. Low coil voltage while cranking means weak spark and no running bike.

The 12v you see on the yellow\white - blue\ black etc... wires all lead back to the ignition box and the box will give a brief ground pulse which will fire the coil.

As for the low P/G coil readings, I find it hard to believe you have 6 that all read the same slightly below spec resistance. I mean, if it left the factory with a 480 ohm resistance, what could possibly shift it to a lower resistance? Have you tried a different multimeter? Maybe you have a friend with a meter just to rule that out?

Did your new P/G come attached to the bracket? The 86 units had no bracket, the 87-89 had a sheetmetal bracket (did it? it might be aluminum as well, but with philips screws) and the 90 and up had a thick aluminum bracket (with allen head screws).

I attached pics of the 87-89 and 90+. You can see differences in the gold metal mounting brackets.

 

As a side note, if you lean the bke over to the left at about 45* you won't have to drain the oil. Once I used a rope around the frame and a tree to lean the bike to the left to change the neutral switch. Didn't loose a drop of oil. :eagerness:

 

Looks like I got a lot to do today . The P\G's on my bike read 291 & 302 . Set just got read 360 & 361 . Hears a pik of them . They look like the correct ones to me . Do you agree ? Set still on my parts bike read 358 & 361 . It crossed my mind also that my meter may be giving me false readings . I will retest with another meter A.S.A.P. As to checking key switch , I check voltage going in & out , right ?

 

That picture looks correct.

You don't need to check the key switch (not yet anyway), you need to check the coil voltage on the black/white wire with the key turned on and most importantly while cranking.

 

And also go back and read post 68 and do that test, it will test coil, plug lead,plug cap and spark plug, and for kicks an giggles do the test on all 4 plugs. Another thing is you say you have a weak spark on 1 & 3, this proves that pulse coil is doing its job, pulse coil only sends a signal to the CDI unit and it is obviously doing that, weak spark is something happening at the coil, even the CDI won't make a better spark, it only tells the coil it has to spark

 

Ok great ! Thanks so much for all the help . First thing for me to do is to get an alternate meter to see if mine is operating correctly . Wish me luck ?

 

Just a note, I wouldn't call the ignition box a "CDI" because that is a completely different type of ignition system and I wouldn't want anyone to get confused.