Coil/Carb Problem ? 1980 KZ750-4

  • DobbinsCMA
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Coil/Carb Problem ? 1980 KZ750-4

03 Nov 2015 20:31 - 04 Nov 2015 04:55
#697124
Well I took the kz750 out for a spin and noticed 1 and 4 weren't firing. I took it home and went to put it on the center stand. My lady came downstairs and I turned to look at her and dropped the bike as I was putting it to the stand. Everything was fine despite the points cover which cracked a little. Funny thing is, those screws were stuck and mangled and now they aren't!

I also had an exhaust leak where the 2 into 2 meet on the left side. Took the exhaust off and the middle piece broke. I had this happen to my first kz and know how to fix it. Still sucks.

I didn't have crush washers at the time (they are on order as I thought I might get one good use out of the old ones) and when I started it up, cylinder 4 was dripping gas from the hole in the exhaust and from the header! Cylinder 1 is firing but not as hot. The plugs seem a little rich on the middle ones (by a tiny bit) but 1+4 look lean. At first k thought it was gas starvation but after the dripping gas seems still to be a spark issue despite having spark when I test the plugs. Bad coil?

Ideas? Bad timing? Valves not adjusted? Do I need to check them? Do a compression check, leak down test?

Also did the 1980 kz750 have electric or points? Mine has electric.
'80 Kz1000B4
MTC 1075 .375 webcams Mikuni RS34
KZ440 Project
81'KZ750E2 Project
Past- '81 Kz750H :(
Last edit: 04 Nov 2015 04:55 by KZQ. Reason: Make topic searchable.

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  • floivanus
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Re: Dumb good thing.

03 Nov 2015 20:48
#697128
1 and 4 not firing could be bad pickup, ignitor going out or bad coils as you say. Would start by checking connections, if they arent good clean metal make them clean. Then work from there. Gas dripping, carb issue.

Also i believe the vast majority of KZs (if not all) had electronic ignition by 1980
my bikes; 80kz1000(project), 77 gl1000, 74 h2 (project)
Past; 78 kz1000, 83 kz550
Andrew

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Re: Dumb good thing.

03 Nov 2015 20:55
#697130
Gas dripping from the exhuast not the carb. Like during the compression stroke, no fire, then exhuast stroke, gas pushed into header. No seal (my washers are toast) so it drips out top and out the hole in the bottle of exhaust.

My kz440 has points and that's an '81. Also manual I have talks about points...
'80 Kz1000B4
MTC 1075 .375 webcams Mikuni RS34
KZ440 Project
81'KZ750E2 Project
Past- '81 Kz750H :(

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Re: Dumb good thing.

03 Nov 2015 22:21
#697132
That's why I said most, I believe the 200, 305 and the 440 are points but the 550/650/750/1000/1100/1300 are electric.

Gas in the exhaust (or excess gas anywhere) points to a carb issue, I believe the CV type carbs don't have overflow tubes so when they do overflow they go in the exhaust or the airbox
my bikes; 80kz1000(project), 77 gl1000, 74 h2 (project)
Past; 78 kz1000, 83 kz550
Andrew

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  • pete greek1
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Re: Dumb good thing.

04 Nov 2015 06:16
#697173
floivanus wrote: 1 and 4 not firing could be bad pickup, ignitor going out or bad coils as you say. Would start by checking connections, if they arent good clean metal make them clean. Then work from there. Gas dripping, carb issue.

Also i believe the vast majority of KZs (if not all) had electronic ignition by 1980

1980 still had points, It had to be 81 or 82 that they went to electronic
Pete
1980 LTD 1000..,1976 LTD 900, have the 1000&900 now. the rest are previous= 1978 KZ 650 B.., 1980 Yamaha XT 500..,1978 Yamaha DT 400.., 1977 Yamaha yz 80..,Honda trail ct 70.., Honda QA 50...5-1/2 hp brigs & straton CAT chopper mini bike...3-1/2 hp mini bike (WHEN GAS WAS ABOUT 45 CENTS A GALLON)!!!!

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  • JR
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Re: Dumb good thing.

04 Nov 2015 06:22 - 04 Nov 2015 06:25
#697175
1980 kz750-4 and years following has electronic ignition.

The 1980 750 twin may have had points but the 750-4s which were introduced in 1980 all came with electronic
1980 kz750E1, Delkevic exhaust
Last edit: 04 Nov 2015 06:25 by JR.

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Re: Dumb good thing.

04 Nov 2015 07:15
#697182
So a clear tube test to test the overflow. Tested coil and is still good. Odd that there is a problem with 1+4 but not coil related.
'80 Kz1000B4
MTC 1075 .375 webcams Mikuni RS34
KZ440 Project
81'KZ750E2 Project
Past- '81 Kz750H :(

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Re: Dumb good thing.

04 Nov 2015 08:10 - 04 Nov 2015 08:11
#697192
JR wrote: 1980 kz750-4 and years following has electronic ignition.

The 1980 750 twin may have had points but the 750-4s which were introduced in 1980 all came with electronic

My 1980 LTD 1000 B4 came with points
Pete
1980 LTD 1000..,1976 LTD 900, have the 1000&900 now. the rest are previous= 1978 KZ 650 B.., 1980 Yamaha XT 500..,1978 Yamaha DT 400.., 1977 Yamaha yz 80..,Honda trail ct 70.., Honda QA 50...5-1/2 hp brigs & straton CAT chopper mini bike...3-1/2 hp mini bike (WHEN GAS WAS ABOUT 45 CENTS A GALLON)!!!!
Last edit: 04 Nov 2015 08:11 by pete greek1.

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  • bountyhunter
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Re: Dumb good thing.

04 Nov 2015 10:05
#697207
DobbinsCMA wrote: So a clear tube test to test the overflow. Tested coil and is still good. Odd that there is a problem with 1+4 but not coil related.
Really odd. Bench testing a coil is usually not accurate and most flaky coils start missing when hot.
1979 KZ-750 Twin

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  • floivanus
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Re: Dumb good thing.

04 Nov 2015 10:11
#697208
pete greek1 wrote:
JR wrote: 1980 kz750-4 and years following has electronic ignition.

The 1980 750 twin may have had points but the 750-4s which were introduced in 1980 all came with electronic

My 1980 LTD 1000 B4 came with points
Pete

Pete I find that extremely odd, last year I had SIX 1980 ltds, five had the factory electronic setup, One had a dyna S, but the wiring harness had the six pin breakout for the ignitor. Check your motor numbers and see if it by chance had a 79 motor in it?
my bikes; 80kz1000(project), 77 gl1000, 74 h2 (project)
Past; 78 kz1000, 83 kz550
Andrew

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Re: Dumb good thing.

04 Nov 2015 11:04 - 04 Nov 2015 11:16
#697214
floivanus wrote:
pete greek1 wrote:
JR wrote: 1980 kz750-4 and years following has electronic ignition.

The 1980 750 twin may have had points but the 750-4s which were introduced in 1980 all came with electronic

My 1980 LTD 1000 B4 came with points
Pete

Pete I find that extremely odd, last year I had SIX 1980 ltds, five had the factory electronic setup, One had a dyna S, but the wiring harness had the six pin breakout for the ignitor. Check your motor numbers and see if it by chance had a 79 motor in it?
It even says it in the Kawasaki service manual for the 1980 LTD, & yes my bike had an igniter, about 15 yrs. ago I had my motor rebuilt with a 1075 kit & I bought a Dyna 2000 to have the guy doing the job install
as you can see points & condenser for 77-80 KZ 1000s
www.z1enterprises.com/ItemDetails.aspx?i...Z1000&item=SU634-611
Pete
1980 LTD 1000..,1976 LTD 900, have the 1000&900 now. the rest are previous= 1978 KZ 650 B.., 1980 Yamaha XT 500..,1978 Yamaha DT 400.., 1977 Yamaha yz 80..,Honda trail ct 70.., Honda QA 50...5-1/2 hp brigs & straton CAT chopper mini bike...3-1/2 hp mini bike (WHEN GAS WAS ABOUT 45 CENTS A GALLON)!!!!
Last edit: 04 Nov 2015 11:16 by pete greek1.

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