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10 amp Ignition fuse keeps blowing 17 Apr 2015 13:06 #668416

  • RFE81LTD1K
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81 KZ1000 LTD

OK, so if any of you read my story on getting my old bike back then you already know it hasn't been ridden in about 12 years. Fast forward to a couple of weeks ago when I finally went and picked it up from the friend I had sold it to 22 years ago.
After doing everything you should do to get an engine running that has set for so long it was time to spin it over without plugs in it. I hit the start button and nothing happened. I had been told it may have an electrical problem possibly due to the bad master cylinder leaking fluid on/into the right control. (on/off/start switch) I decided to try just flipping the on/off/start switch back and forth numerous times and to my amazement it started working. Engine turned over fine. Fast forward again ... put everything back together, poured gas in the tank and it fired right up. :woohoo: I was blown away how easily it started. So out the driveway I went to ride around the block a couple of times. Rode it for about 5-10 minutes but when I came to a stop it just quit. Still had power to everything except the ignition and horn. WTF??? After a few minutes i figured out it had blown the ign/horn fuse. OK, so I replaced the fuse and it fired up again. Rode it back to the house. Decided maybe the fuse was just old and week and decided to go for another ride. Less than 10 minutes later I pull up to another stop sign and it quit again. Luckily I had put an extra fuse in my pocket so after replacing it again I made it home. I pulled the tank and side covers and started checking harness plugs and wiring for bad/loose/chafed wires. Didn't really find anything obvious but did re-wrap a couple of harnesses and tied up the red coil wire that was laying on top of the engine. Once more I go for a ride. Ran great for about 30 minutes so I thought my problem had been fixed. A few minutes later my son wanted to take it for a ride so off he went. 10 minutes later he pulls up with the engine running like crap as if on 2 cylinders. I didn't look at it for about 30 minutes or so but when I did it started it up and it ran fine. I haven't ridden it again to see if the problem persist but suspect sooner or later it will.
So, first is/was the issue with the ign fuse blowing. Somewhere prior to re-wrapping harnesses I missed telling you it had blown two other times less than a block down the street.
Second is when it started running badly. ??? Is it possible for a coil to draw too many amps and blow the ign fuse? And ... now be cutting out but not blowing the fuse? Or do I have 2 separate issues?
At this point a can't trust it to go any further than a couple of blocks from home. Or should I say any further than I'm willing to push it. And I'm toooo damn old to be pushin it. LOL.
81 KZ1000 LTD
All original.
15k miles.
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10 amp Ignition fuse keeps blowing 17 Apr 2015 14:20 #668423

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Coils could have developed a short. Turn on everything and run it to see if the fuse blows again. You can do a OHM test on the coils too but sometimes it doesn't show up.
Steve
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10 amp Ignition fuse keeps blowing 17 Apr 2015 14:23 #668424

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RFE81LTD1K wrote: 81 KZ1000 LTD

OK, so if any of you read my story on getting my old bike back then you already know it hasn't been ridden in about 12 years. Fast forward to a couple of weeks ago when I finally went and picked it up from the friend I had sold it to 22 years ago.
After doing everything you should do to get an engine running that has set for so long it was time to spin it over without plugs in it. I hit the start button and nothing happened. I had been told it may have an electrical problem possibly due to the bad master cylinder leaking fluid on/into the right control. (on/off/start switch) I decided to try just flipping the on/off/start switch back and forth numerous times and to my amazement it started working. Engine turned over fine. Fast forward again ... put everything back together, poured gas in the tank and it fired right up. :woohoo: I was blown away how easily it started. So out the driveway I went to ride around the block a couple of times. Rode it for about 5-10 minutes but when I came to a stop it just quit. Still had power to everything except the ignition and horn. WTF??? After a few minutes i figured out it had blown the ign/horn fuse. OK, so I replaced the fuse and it fired up again. Rode it back to the house. Decided maybe the fuse was just old and week and decided to go for another ride. Less than 10 minutes later I pull up to another stop sign and it quit again. Luckily I had put an extra fuse in my pocket so after replacing it again I made it home. I pulled the tank and side covers and started checking harness plugs and wiring for bad/loose/chafed wires. Didn't really find anything obvious but did re-wrap a couple of harnesses and tied up the red coil wire that was laying on top of the engine. Once more I go for a ride. Ran great for about 30 minutes so I thought my problem had been fixed. A few minutes later my son wanted to take it for a ride so off he went. 10 minutes later he pulls up with the engine running like crap as if on 2 cylinders. I didn't look at it for about 30 minutes or so but when I did it started it up and it ran fine. I haven't ridden it again to see if the problem persist but suspect sooner or later it will.
So, first is/was the issue with the ign fuse blowing. Somewhere prior to re-wrapping harnesses I missed telling you it had blown two other times less than a block down the street.
Second is when it started running badly. ??? Is it possible for a coil to draw too many amps and blow the ign fuse?.

YES. And on mine, the coil is wired right after the big fuse so it would blow it if there was an intermittent short. With coils, the problem may only show up after running which heats the coil up. If the coil is old or shows surface cracks, it should get booted.
1979 KZ-750 Twin
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10 amp Ignition fuse keeps blowing 17 Apr 2015 15:22 #668433

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Thanks guys. There's no doubt the coils are old. 34 years to be exact. I'm gonna set up a good fan in front of it and let it run for ??? a while and see what happens. If it blows the fuse it'll just quit running. If it starts running bad I'll do a spark test (with a tester) before anything has a chance to cool down. If spark is lost I'll swap the coils and see if it duplicates the failure on the other two cylinders.
If a coil is found to be the culprit, which coils from Z1 do yall suggest? Their Dyna 2.2 ohm or green 3.0? and what are the advantages and or disadvantages between the two?
If not Dyna coils then who's? Are any of the aftermarket varieties on ebay worth a ___?

Back to the fuse blowing. So far ... or since I re-wrapped the harness going through the front forks and tied up the red coil wire it hasn't blown another fuse. I do however still need to check the loom at the headlight. So what about that questionable 3 way (off ... on/start ... off) control switch not working till I fiddled with it and then miraculously started working. Somehow, once the engine is running I don't really see it causing the fuse to blow. Seems to me if it was the switch itself it would blow the fuse as soon as I hit start. ??? I may have isolated the fuse issue by simply doing what little re-wrapping I did and or by tying up a couple of wires. Time will tell.

Any other thoughts or idea's on this would be appreciated.

Robert
81 KZ1000 LTD
All original.
15k miles.
Last edit: by RFE81LTD1K.
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10 amp Ignition fuse keeps blowing 17 Apr 2015 16:47 #668445

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I went through both of my controls when I didn't have the money for the engine. Dirty, dry and corroded. I cleaned them up and they work fine. The high beam switch broke so I bought a new aftermarket one from Z1 parts inc. $45
I'm keeping the stock one. It's is worth money rebuilt. A Z1 you know. It has the date code.
Steve
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10 amp Ignition fuse keeps blowing 17 Apr 2015 17:25 #668452

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OK, I just ran it and found my #2 plug wire cap is getting reallllly hot. ??? At the very least it's time for some new wires. Question is should I buy wires for these old stock coils or just go ahead and replace the coils and wires with Dyna's? Yeah, never mind. It's pretty much a no brainer.
From the word go it was running like crap. Even tried going down the block but couldn't keep it running. If I didn't know better it acts like it's running out of gas. (has half a tank) After it cools down I'll check it for flow anyway.
Other than the #2 cap getting hot the spark test was good. So if it has good spark the only thing left is fuel or the lack there of. When I checked the tank it was dry and clean. My buddy told me he had cleaned it but never put gas in it. Doesn't have any rust and didn't hear anything rattling around in it. The valve was leaking a little so I replaced the o-ring in it. Other than that the valve itself was clean.
How does the vacuum on that valve work. I assume it's only supposed to deliver fuel when the engine is pulling vac. Yeah, about that. Previously when I've taken the tank off it flows fuel all the time no matter what position the valve lever is in. Strangely it kinda makes since that it could be a fuel issue. Right when I start it / it runs fine. Try to ride it / it'll hardly run. Let it sit for a few minutes and sitting still it runs fine again. ??? I don't think its float related. When I cleaned the carbs they actually looked pretty good. One float was stuck but naturally I cleaned everything and they all appeared to be working fine.
So ... I don't know guys. I guess in a nut shell I've got a couple of stubborn gremlins I'm gonna have to hunt down and evict from the premisses. Maybe one of those cute little bells that's supposed to ward um off would help. LOL.
81 KZ1000 LTD
All original.
15k miles.
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10 amp Ignition fuse keeps blowing 17 Apr 2015 17:50 #668456

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swest wrote: I went through both of my controls when I didn't have the money for the engine. Dirty, dry and corroded. I cleaned them up and they work fine. The high beam switch broke so I bought a new aftermarket one from Z1 parts inc. $45
I'm keeping the stock one. It's is worth money rebuilt. A Z1 you know. It has the date code.
Steve

Yeah, my switches looked about the same. Cleaned um up with some ele contact cleaner and a small brush. So far they seem to be working fine.
81 KZ1000 LTD
All original.
15k miles.
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10 amp Ignition fuse keeps blowing 17 Apr 2015 18:30 #668460

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Clear tube test on the carbs.
A little trick. When painting the switch blocks, paint the black first, then use oil paint for the letters and such. Use a Q tip then wipe off the excess. That's how they've done it for ever.
Steve

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10 amp Ignition fuse keeps blowing 17 Apr 2015 23:51 #668483

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Got ya. I'll try some clear tube. Thumbs up on your controls. Has a clean look.
I painted inset letters/numbers like that back when I was doing stenciling in a machine shop. Everything had to have the part number on it and they wanted it to be easily seen. But all we had to do was spray um white and wipe off the over spray.

Here's another little tip ... Fingernail polish works too. Its also impervious to gas and oil. Have to use acetone/nail polish remover to clean/remove it. Plus they have every color you could possibly want, Also works good to seal those small plugs you often find on carburetors. (look like tiny freeze plugs) Pop it in and paint a little nail polish around the edges.
81 KZ1000 LTD
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15k miles.
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10 amp Ignition fuse keeps blowing 18 Apr 2015 01:50 #668487

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An intermittent electrical that causes misfiring on two cylinders is so likely to be the coil, I would not screw around with it. Coils wear out from heat. Trying to run a 34 year old coil is like trying to run a 15 year old battery. If your bike has points, use a 4 or 5 Ohm coil. If it has the Kawi electronic ignition, I think they use low impedance coils like 3 Ohm ballpark.
1979 KZ-750 Twin
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10 amp Ignition fuse keeps blowing 18 Apr 2015 10:01 #668536

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Most breakdowns on the road are electrical, any old bike I get I always do this first. Also it gives me a lot more peace of mind that I'm less likely to be caught out in pitch darkness miles from home, even though I carry tools, spares fuses and a torch.

As a minimum, if you think you have sorted it, try to make it blow again - wiggle the harness everywhere, turn your bars from lock to lock. Occasional short circuits where a live is damaged and grounds somewhere on the frame are often the hardest to find. You know it is/was on your fused ignition feed, ignore all other circuits for now.

Another advantage of going through the whole system is really bright lights and on-the button starting.
1980 Gpz550 D1, 1981 GPz550 D1. 1982 GPz750R1. 1983 z1000R R2. all four aces
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10 amp Ignition fuse keeps blowing 18 Apr 2015 11:15 #668542

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You guys make good points. I agree on the coils. Not to mention the 34 year old wires and caps. I talked to somebody at Z1 yesterday and came about this close " -" to ordering a set of coils and wires. Only thing that stopped me was not knowing what ohm to get. Z1 recommended 3 ohm but I read somewhere about 2.2 ohms being right for these engines. To be honest I don't know what difference .8 of an ohm would make in how it functions. ???
I hear ya about getting stranded. I wasn't far from home the first time it blew the ign fuse but it was far enough that I didn't want to have to push it there. These bikes don't offer much as far as space to carry many tools. Believe it or not this thing still has the factory tool kit in tact. And the original owners manual
I read what some of you were telling a young kid about keeping his bike stock or at the very least saving all the original parts he replaces with aftermarkets. I couldn't agree more. Although a nice deep throated 4-1 header sounds really good on these beast.

Here's a pic of what we're working on ...

Attachment 81KZ1000LTD9-2.jpg not found




Thanks again guys.
Robert
81 KZ1000 LTD
All original.
15k miles.
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