Weak, tiny spark, kz750 twin

ElSombreroNegro
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Weak, tiny spark, kz750 twin

16 May 2011 17:36 - 16 May 2011 17:40

I got it all put together and started cranking it over.:woohoo:

Did that for an hour and it wont start :blink:

Spark plug have gas on them, so it is getting gas.

13.1 volts at the coil input/hot

Cranks over and DOES spark, just very weak and puny.

Just replaced the condenser, they are cheap.

Hooking up to jumpers to give the battery a boost has no effect on spark quality.

Come on and throw some ideas at me guys! I am near my wits end with this damn thing!
Wiring makes my head hurt...:pinch:

(Mostly) 1976 KZ750 Twin in a (Mostly) 1978 KZ200 frame (dont ask me what I was thinking)

Last edit: 16 May 2011 17:40 by ElSombreroNegro. Reason: spelling

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Topper
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Re: Weak, tiny spark, kz750 twin

16 May 2011 17:46

#451503

Are the sparks hot blue or cool orange?

I assume you've replaced the spark plugs and that they're the proper one's for the bike?

Permanent and perpetual noob.

1979 KZ750 Twin
2009 Kawasaki Versys

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ElSombreroNegro
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Re: Weak, tiny spark, kz750 twin

16 May 2011 18:03 - 16 May 2011 18:06

#451507

They are blue, and just strong enough to be seen outside in the shade. Been foolin with this thing all day. The plugs are both old, I should replace them, but they are clean. Both of the are sparking weak on either lead.

Just to rule this out: #1 cylinder is indeed on the left, as you are sitting on the bike?

Also, does the coil have a hot and a ground that HAS to be hooked a certain way? Because I get the same weak spark either way, but just grassping at straws here..

(Mostly) 1976 KZ750 Twin in a (Mostly) 1978 KZ200 frame (dont ask me what I was thinking)

Last edit: 16 May 2011 18:06 by ElSombreroNegro. Reason: more info

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Patton
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Re: Weak, tiny spark, kz750 twin

16 May 2011 18:07 - 16 May 2011 18:08

#451509

If not already done, would ohm-test coil primary and secondary.

Good Fortune!

1973 Z1
KZ900 LTD

Last edit: 16 May 2011 18:08 by Patton.

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ElSombreroNegro
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Re: Weak, tiny spark, kz750 twin

16 May 2011 18:10 - 16 May 2011 18:10

#451511

Refresh my memory.. What numbers am I looking for on the multi meter?

(Mostly) 1976 KZ750 Twin in a (Mostly) 1978 KZ200 frame (dont ask me what I was thinking)

Last edit: 16 May 2011 18:10 by ElSombreroNegro.

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Patton
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Re: Weak, tiny spark, kz750 twin

16 May 2011 18:26 - 16 May 2011 18:28

#451516

Including information about bike year and model may elicit better responses.
And it's easy to put in your signature where it will automatically appear in posted messages.
When done, the signature information appears in all posts, past and future.

And may be changed as often as desired.

Just guessing, would guess coil primary at 3Ω with points ign or 2.2Ω ohm with Kaw elec ign, and secondary with either ign at way high ohms such as maybe 15k~18k ohms.

Should find an FSM most helpful.

Good Fortune!

1973 Z1
KZ900 LTD

Last edit: 16 May 2011 18:28 by Patton.

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ElSombreroNegro
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Re: Weak, tiny spark, kz750 twin

16 May 2011 19:47

#451541

Ok datgummit! Now the coil is VERY hot to the touch, AND now I got NO spark!

Resistance hot to ground tab is 7 ohms and R to leads maxed out my Snap-On multimeter.

Pretty safe to say my $20 ebay coil is poo-poo.

(Mostly) 1976 KZ750 Twin in a (Mostly) 1978 KZ200 frame (dont ask me what I was thinking)

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bountyhunter
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Re: Weak, tiny spark, kz750 twin

17 May 2011 02:09 - 17 May 2011 02:11

#451652

Patton wrote: If not already done, would ohm-test coil primary and secondary.

Good Fortune!

I would punt the old coil into the can and buy the new Four-Ohm EMGO coil at Z1 for the bargain price of $36. The 750 twins with points run a four Ohm coil. I am running one on my 750 twin and it really cranks spark. Old coils do not age well. Guess how I know...

1979 KZ-750 Twin

Last edit: 17 May 2011 02:11 by bountyhunter.

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ElSombreroNegro
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Re: Weak, tiny spark, kz750 twin

17 May 2011 03:28

#451661

Will do, and thanks for the help guys.

(Mostly) 1976 KZ750 Twin in a (Mostly) 1978 KZ200 frame (dont ask me what I was thinking)

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hallin222
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Re: Weak, tiny spark, kz750 twin

20 May 2011 18:35

#452448

Helpful thread. Thanks. I have a similar problem on my 1979 KZ750B (or 1980 KZ750G). I'm not sure which the motor came out of. It turns over ok, but won't fire. Getting gas, but spark is very faint. My voltage INTO the coil was also over 12 volts, so I assume the points system is ok. I may just have to break down and buy a new coil myself.

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loudhvx
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Re: Weak, tiny spark, kz750 twin

21 May 2011 12:48 - 21 May 2011 12:49

#452568

ElSombreroNegro wrote: I got it all put together and started cranking it over.:woohoo:

Did that for an hour and it wont start :blink:

Spark plug have gas on them, so it is getting gas.

13.1 volts at the coil input/hot

Cranks over and DOES spark, just very weak and puny.

Just replaced the condenser, they are cheap.

Hooking up to jumpers to give the battery a boost has no effect on spark quality.

Come on and throw some ideas at me guys! I am near my wits end with this damn thing!
Wiring makes my head hurt...:pinch:

Just in case...

Did you happen to take apart the timing advance mechanism?
If so, and if it's like the inline-four motors, there is a chance that the rotor is installed backwards. This would make the spark fire just before bottom-dead-center, rather than before top-dead-center. This can explain having gas and spark, but no fire.

Just checking.

Oh, and I agree, don't waste time with old coils. That can get you stranded, usually in the rain.

1981 KZ550 D1 gpz.
Kz550 valve train warning.
Other links.

Last edit: 21 May 2011 12:49 by loudhvx.

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ElSombreroNegro
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Re: Weak, tiny spark, kz750 twin

21 May 2011 16:50

#452589

Yeah, I had thought about that and triple checked to be sure. It has a keyway and I found it only goes on the one way. The new coil should be in today! We will see how that pans out.

Thanks again for the help guys. Will post how it turns out.. Personaly, I hate to be left hanging on a subject..

(Mostly) 1976 KZ750 Twin in a (Mostly) 1978 KZ200 frame (dont ask me what I was thinking)

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