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Author Topic: Weird intermittent spark  (Read 5657 times)

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Offline Vinhead1957

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Re: Weird intermittent spark
« Reply #50 on: March 20, 2016, 07:50:39 AM »
If so, all he would need to do is move a cap and cylinder 1 would fire. Nothing is proven yet.  Suspect caps but prove it
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Offline Sdsbassist

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  • Gus, Austin, MN.
Re: Weird intermittent spark
« Reply #51 on: March 20, 2016, 07:55:14 AM »
I'll let you guys know. That's what bothered me too. Switched wired and still jack squat. My plan is to get caps and plugs and do a once over on carbs too to see if there is anything suspect. If it is carbs, I need new caps and plugs  anyways.

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Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

Offline calj737

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Re: Weird intermittent spark
« Reply #52 on: March 20, 2016, 09:10:16 AM »
Except that 3 of 4 of his caps tested BAD. The wire he switched to 1 was also bad, so a meter reading on plug caps is pretty darn impirical evidence.
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'74 550 Build http://forums.sohc4.net/index.php?topic=126401.0
'73 500 Build http://forums.sohc4.net/index.php?topic=132935.0

"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline Sdsbassist

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Re: Weird intermittent spark
« Reply #53 on: March 20, 2016, 09:11:07 AM »
Yes...I agree

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Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

Offline PeWe

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Re: Weird intermittent spark
« Reply #54 on: March 20, 2016, 01:13:05 PM »
I had intermittent ignition on 1 cyl 1 year ago. New wires were the last to replace. Dynatek surpressed graphite wires... Not a good choice in my case, CU wires and NGK 5kohms caps solved that tricky problem.
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CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline Sdsbassist

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  • Gus, Austin, MN.
Re: Weird intermittent spark
« Reply #55 on: March 20, 2016, 01:27:11 PM »
Tha s for the input pewe...I'm excited to see how the new caps react. Is there a good way to make sure they have good contact?

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Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

Offline PeWe

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Re: Weird intermittent spark
« Reply #56 on: March 21, 2016, 04:26:06 AM »
I finally noticed that which cylinder that had intermittent function when it was not functional during a longer time and exhaust cold.
Used another wire and it worked better direct. Easy to change wires when I use Dynatek coils (5ohms)
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CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline Gene

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Re: Weird intermittent spark
« Reply #57 on: March 21, 2016, 11:54:17 AM »
Quote from: Deltarider on March 20, 2016, 12:53:21 AM
Quote
when I score some case replace all spark related stuff and see if it helps.
Do it step by step so you (and we) will learn what caused your problem. There are owners who just throw a lot of money in their bike by replacing all related stuff in one time, hoping the bike will see and value the offer. Alas, a bike is not like that.

Do you mean to tell me that these bikes are not like the old Gods? I've been going at this entirely the wrong way . . .
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*1973 CB750K3 (Bow)

Offline Sdsbassist

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Re: Weird intermittent spark
« Reply #58 on: March 22, 2016, 06:47:51 PM »
So for fun I pulled carbs while I wait for my caps. They were full of crap. Rookie mistake. Caps needed replacing anyways. Excited to see what happens.

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Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

Offline Stev-o

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Re: Weird intermittent spark
« Reply #59 on: March 22, 2016, 06:50:49 PM »
Is you tank clean?
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'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline Sdsbassist

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Re: Weird intermittent spark
« Reply #60 on: March 22, 2016, 06:51:47 PM »
Looks clean. I'm gonna run what's in there out (was from can in garage) and get new to be sure.

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Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

Offline Stev-o

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Re: Weird intermittent spark
« Reply #61 on: March 22, 2016, 06:56:04 PM »
Yeah, drain it out and see if there is crap in there.  If yes, you may need to at least flush it out.
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'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline Sdsbassist

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  • Gus, Austin, MN.
Re: Weird intermittent spark
« Reply #62 on: March 23, 2016, 08:44:05 AM »
New caps, gas, clean carbs and all five fire like gold. Gonna time and make sure it's all good. If it weren't for a predicted 10" of snow, I'd ride.

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Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

Offline Stev-o

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Re: Weird intermittent spark
« Reply #63 on: March 23, 2016, 08:51:35 AM »
Quote from: Sdsbassist on March 23, 2016, 08:44:05 AM
...
all five fire like gold



FIVE?!  Awesome news, dont let a little snow stop you! Might make a good video.
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'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline Sdsbassist

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  • Gus, Austin, MN.
Re: Weird intermittent spark
« Reply #64 on: March 23, 2016, 08:51:55 AM »
Four. Jeepers.

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Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

Offline calj737

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Re: Weird intermittent spark
« Reply #65 on: March 23, 2016, 08:53:21 AM »
Maybe he has the uber rare Peugot-powered CBV that is the stuff of legends???
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'74 550 Build http://forums.sohc4.net/index.php?topic=126401.0
'73 500 Build http://forums.sohc4.net/index.php?topic=132935.0

"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline RevDoc

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Re: Weird intermittent spark
« Reply #66 on: March 23, 2016, 07:42:58 PM »
Quote from: calj737 on March 23, 2016, 08:53:21 AM
Maybe he has the uber rare Peugot-powered CBV that is the stuff of legends???

 ;D
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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!!"
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