Topic: 1978 CB750K8, 76 engine, running on 2 cylinders :-)

[SiliconDoc]

 Well, I'm proud of myself. I thought I was losing my touch, but it turns out only half the engine is sparking - so the hassles carb tuning and setting the points have just this morning become clear.
 I knew the right side tailpipe wasn't blowing as hard as the left, and had thought it was plug wire #3, which I just trimmed, even though #4 sent a strong strobe signal to the timing light, and #3 did a bit and #2 did it seemed, I assumed it was the wire covers on #2 and #3 blocking the strobe signal, whereas on #4, it was just the 7 or 8 mm core exposed.
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So I get out there 10 mins ago and clip #3 wire like the help here suggested ( Thank you members ) - yeah it's a copper wirestrand core all right - put the cap back on and start her up - ran just like my 10 mile trip last night - ON TWO CYLINDERS I find out!
LOL
Yeah, NO HEAT on the right pipes - ZERO - and she's sitting there running....
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Guess I'll have to change the oil as soon as I correct that little problem...
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No wonder I couldn't get "the points set correctly" or so it seemed.
Yes, I wimped out and bought a DS-2 electronic ignition and installed it.
Yes, I was whacking away on the floatbowl idle screws for a week.
Yes, I hope the electronic ignition and/ or 2,3 coil isn't fried.
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Last night before the ride I pulled #3 wire while it was running, no change in speed but the main fuse blew seconds later.
 I replaced it and took my 5 mile trip to the client's party I was invited to.
 Got stopped for no taillight and a warning ticket issued, the cops were very curious about the bike and we were talking for 10 mins - the taillight is on/off depending on the "short" in the "switch" key area - if the key is just so it's on.
 When I pulled into the lot and she died, the taillight remained on. Ahh haaaaa -" See officer, it's ON, maybe you're seeing things ? "
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Ok, so anyway, I'm very hopeful now that it will run GREAT like it did two years ago - I guess I've been tuning with only 2 cylinders going most of the time.
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Yes, I was bragging there at the beginning, you were probably laughing - ha, oh crap I'm scared to go out there and rev her up and see if she's really stoking on just 2 cylinders and that has been my problem... it just can't be.. can it ?

[SiliconDoc]

Since I'm impatient for attention, I'll add a bit.
I tested the #3 plug cap and she read about 4,300 ohms - from reading yesterday, this morning, it appears that is correct.
THANK YOU AGAIN SOHC members for all your little expertise. I can't say which threads or whom it was, but I see people are helpful here, and that's great.
 Maybe I didn't get the wire into the cap good enough, and that killed #2 and #3 ? Remember it has the Dyna DS-2 on it now... so I'll check the little pigtails to the blue and yellow (I think blue is 2 and 3 - I'll check first).
 Jeeze, hope I didn't fry something.
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I also ran through the connections under the left side cover yesterday, and the right front blinker which was dim/goofy.
The turn signals respond VERY SLOWLY, like 3 seconds or 10 seconds for a blink...even under high revs.
Two years ago I tested the charging - and it was good. I replaced the (stator?) under the left engine cover(and cover) from the other engine - my friend crashed it on the way to Dad's a few years ago, left it in his parents barn, then when he moved to Kansas and was going to throw it out, I chewed him, so they brought it over and dumped it here. :-)
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I couldn't figure out how to post in introductions so there is a sort of one. I registered for picks, so get ready for some Survivor Shed 750 pics you'll have a hoot over.

[SiliconDoc]

Ok, yeah it starts up and revs up, #3 pipe got just a bit warm this time, #4 still dead cold, #1 and #2 are blazing hot.
So it looks like plug #3 (which I replaced before the trip last night) might clear up since I cut 1/4" off the wire and reinserted (yes it was BAD, copper core kilted to one side, hole from the cap 1/16th" away from core strands- no contact it appeared).
 Just hacked #4 wire too, pulled the oil fouled plug, cleaning now.
Isn't this exciting?
lol

[OldSchool_IsCool]

Could it be that you have the #3 wire connected to the #4 plug and verse visea?

[SiliconDoc]

Ahh, thanks for the idea, but they are labelled, they look original with original coils. Yeah in that second message I said #2 and #3, but no it's #3 and #4.
 I'm more than a bit beat from all these hassles... I just hooked up my "spark tester" - it's an metal TV antenna clip(the old kind with big alligator teeth) and a used plug bail wired to it.
 #1 has mostly blue spark, I wouldn't call it strong blue.
#4 has a weak yellow spark - I'll test again it's easy because I just leave the plug in and clip it to the metal exhaust flange.
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So I'm thinking I have a weak wiring issue - that is affecting strangely 3 and 4 - that would point to the coil wires going to the plugs on 3 and 4,  if 1 and 2 has a strong spark, right ?

[torrinh]

Sounds like a bad plug. If he had the wires crossed it would probably backfire. Maybe low voltage from the battery? That explains the blinkers not working correctly.

[SiliconDoc]

Yeah could be a bad plug - 3 and 4 were kinda soaked since those weren't firing much if at all and I didn't realize it, but I changed 3 last night and pulled and cleaned 4 just now.
It's easy tank off, and I noticed the coils have probably never been removed. Perhaps the grounds on the coils (are there any ?) are rusty ?
 The 8 or 10 mm thick green wired frame ground under the tank on the left side of the frame I cleaned well.
 The phillips head screws holding down the coils in back are rusty bad.
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It's just weird 1 and 2 would have good spark while 3 is near nothing and 4 is weak, isn't it ?

The battery is new but with all this electrical weirdness going on - and cranking, I'll check it's charge.

[SiliconDoc]

Sounds like a bad plug. If he had the wires crossed it would probably backfire. Maybe low voltage from the battery? That explains the blinkers not working correctly.

Ok, after passing out for a few hours, I went to O'reillys and got 4 D8EA and 4 D7EA - the Autozone right next to them did not stock anything but RA8HC (champion equiv.) as far as they could tell- heads up O'Reillys just scored some points.
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Well, I cleaned the yellow and blue DS-2 pigtails, WD40 on the ones under the seat, then took off to O'Reillys and I beat the pants off of it - I was on a twister at 5,000 6,000 7,000 rpm slamming it. I did notice the first couple of times it blew some chunks out the right rear exhaust (2 into 1 on each side). Then at McDonald's on the way back for the must have "Gangus" burger for Honey - she darn near idled @ 1500 without the choke on.
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 That was very fun beating the tar out of it.

[SiliconDoc]

Sounds like a bad plug. If he had the wires crossed it would probably backfire. Maybe low voltage from the battery? That explains the blinkers not working correctly.

I never put the voltmeter to the new battery (it's a month old if that) - I charged it with a 1 amp trickle according to the included instructions initially - so YES, I will take your advice - in a few here (Monday afternoon) it's work time again on it, so I'll check the battery voltage right away and go from there.

Thank you, it seems I need a little helpful kick to do the basic checks that make the simplest of sense sometimes.
Thank you, I really appreciate the comment - I have no idea really if the new battery has a bad cell which it could, or if it's low on charge.

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Ok tests results:

12.22 volts - no key in
11.92 volts start and running low idle cold
14.92 volts @ about 4,000 rpm - climbed slowly up to that over 5-10 seconds maybe

[SiliconDoc]

Ok, while changing the plugs to D7EA, with the tank off...

 I discovered that I left the #2 & #3 12V coil pigtail connector not seated all the way and rather loose in it's dual female receptacle.


 #1 & #4 pigtail was solid as it caught a bit of the solder for the extended DS-2 wire I connected there.

 Cleaned the pigtail & connector with 240 grit, electric cleaner, pinched the female, got her good and tight and zip tied the triple bundle snug.

After work update 8:15 PM Mon. Sept 14th '09 : 4 D7EA in (#2 plug hole threads in head seem a bit stressed), main frame ground redone, plug wires- added protection in case of spark shorts, blue and yellow coil pigtails cleaned.
 It now starts, and stays running and idles up with full choke and no throttle (that's improvement) - but 3 & 4 pipes are still cold.

 I don't understand how I get decent running at speed w/2 cylinders down or half down- I suppose as I open the throttle, air and some gas enter through another carb circuit and the charging circuit ups the sparks - I'm guessing I have fuel flow issues on 3 and 4.
 I'll have to use my spark tester on those two again, and open the bowl drains to see if they are filling.
 I am avoiding pulling the carbs until I know a bit more.