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10 amp Ignition fuse keeps blowing 02 Jun 2015 05:20 #674942

  • SWest
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When I went through the 550 carbs last week, #4 barely passed the thumb test. My ass was puckering the whole time being they are TK's and parts are hard to come by. It runs fine. I do have to use the choke to start it though just momentarily. Thy're made to run lean and that air injection system doesn't help. Try capping off the intake ports. You might have a air leak there.
Steve
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10 amp Ignition fuse keeps blowing 02 Jun 2015 18:15 #675041

  • RFE81LTD1K
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Going back to your question about the carbs. Yes, they're Mikuni CV carbs.
Although I know I should have while the cam/valve cover was off, no I have not checked the valve clearances.
And yes, I did check the diaphragms. They're still relatively soft with no signs of holes or cracking.
Last time I had the carbs off I replaced the vac lines so I wouldn't think I'd have a leak there. But I'll check anyway.

Just order a whole list of parts from Z1 including new float needles. Thinking mine are OK, I decided to wait on new floats. Z1 told me they've seen times when the needle dampers get week causing them to have to be completely compressed before the needle will shut off the fuel. Hence possibly the reason why I had to bend the tangs as far as I did.

Robert
81 KZ1000 LTD
All original.
15k miles.
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10 amp Ignition fuse keeps blowing 02 Jun 2015 22:05 #675066

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The diphgrams can look good and can be. Put your thumb over the large vent in the back after lifting the slides with your finger. Hold your thumb over the vent and see how fast or slow they fall. Slow, good, fast not so good. Air leak.
Steve
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10 amp Ignition fuse keeps blowing 02 Jun 2015 22:07 #675067

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The diphgrams can look good and can be. Put your thumb over the large vent in the back after lifting the slides with your finger. Hold your thumb over the vent and see how fast or slow they fall. Slow, good, fast not so good. Air leak.
Steve
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10 amp Ignition fuse keeps blowing 03 Jun 2015 01:47 #675071

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Ok, I'll check that. But wouldn't a bad diaphragm or any other air leak make it run bad all the time / not just at start up? As before, it runs fine once it gets past whatever this false since of being cold is. The only thing I know of that would do that is something still being wrong in the carbs. I just don't believe an air leak, electrical or ignition problem would just go away after it runs for a minute or so.
Although I don't think my use of the clear tube method lied to me, you have convinced me I shouldn't have had to bend the tangs as much as I did resulting in the possibility of having improperly set floats. We'll see if it changes when I install the new needles and seats. If not ... ???

Robert
81 KZ1000 LTD
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15k miles.
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10 amp Ignition fuse keeps blowing 03 Jun 2015 06:06 #675084

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Yes, they control the slides. With a already lean mixture , the slides not working right could cause it to be overly lean. When it warms up it can run better.The air injection system could have a leak as well.
Steve
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10 amp Ignition fuse keeps blowing 03 Jun 2015 12:39 #675135

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swest wrote: Yes, they control the slides. With a already lean mixture , the slides not working right could cause it to be overly lean. When it warms up it can run better.The air injection system could have a leak as well.
Steve

Yes, I know the diaphragms control the slides and I understand it running better when it warms up. But what about the fact that it's already warmed up and still has to be choked to get it started? (after it sits for 5-10 minutes) If I turn it off and start it right back up again it does fine. It's the sitting after not running for XX minutes it has it's choke to start problem. Then after it's running you would think since it's already warm I could take it off choke almost immediately. No. I have to feather the choke keeping the rpms slightly elevated to keep it running till it (for the lack of better words) clears out and idles without dying. Sure, if I wanted to I could get it past the bogging and sit there revving the engine till it decides to idle but we know that isn't right either.
81 KZ1000 LTD
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15k miles.
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10 amp Ignition fuse keeps blowing 03 Jun 2015 13:05 #675139

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In an earlier posting you stated "........ knowing the use of pod filters is a far cry better than the stock air box......"

I don't know where you got that idea, but it is not factual, especially for a stock engine with CV carbs. If you put pods on it you will spend a fair amount of time and treasure trying to get them to work as well as the stock airbox with the stock air filter in place. Some folks have eventually been successful, but it is not usually a simple task, and there are often lingering performance issues such as the affect of rain and/or side wind.

Regarding the problem of needing to use the choke so much - if you have not done so already I recommend you test the carb holders for air leaks. If air is being drawn in through the carb holders it might explain your need to enrich the air/fuel mixture by using the choke. The effect of carb holder leaks can vary widely as the temperature of the cylinder head and/or carb holder changes. This is because the air leaks in between the mating surfaces through tiny cracks in the rubber, and as these cool or heat up the rubber on the carb holder mating surface may seal or not seal better against the cylinder head. In any event, this is worth checking because it is very easy to do, and if you find a leak it should be corrected.

Carb holders will eventually develop tiny cracks in the mating surfaces between the holders and the cylinder head that can cause them to leak at idle. These cracks cannot be seen with the carb holders in place. I suggest you try the following. Get the engine warmed up and temporarily set the idle as low as possible without killing the engine (lower than 900 rpm if possible). The lower the better because with the idle very low the slides are nearly shut and the vacuum inside the carb holders is at its highest. Then spray carb cleaner around the carb holders, especially where they mate with the cylinder head and where the carbs attach to them. Carb cleaner works best for this test as it doesn't leave an oily mess with WD40 or evaporate so quickly that it is not drawn into the leaks as can happen with propane or starting fluid (ether). If the engine dies or reacts to the carb cleaner, you need to replace the carb holders. Carb holder leak related problems are noticeable at idle but generally don't have much impact when riding because the throttle is open. If you find you need to replace the carb holders soak the screws with Kroil for a couple days before attempting to remove them, and use JIS standard, NOT Phillips, screwdriver bits, and this will greatly improve the odds that you will not break or strip a carb holder fastener as so many have done. Let me know if you need info on JIS bits, I have a good link for making your own at no cost. Ed
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
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10 amp Ignition fuse keeps blowing 03 Jun 2015 16:56 #675155

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650ed wrote: In an earlier posting you stated "........ knowing the use of pod filters is a far cry better than the stock air box......"

I don't know where you got that idea, but it is not factual, especially for a stock engine with CV carbs. If you put pods on it you will spend a fair amount of time and treasure trying to get them to work as well as the stock airbox with the stock air filter in place. Some folks have eventually been successful, but it is not usually a simple task, and there are often lingering performance issues such as the affect of rain and/or side wind.

Regarding the problem of needing to use the choke so much - if you have not done so already I recommend you test the carb holders for air leaks. If air is being drawn in through the carb holders it might explain your need to enrich the air/fuel mixture by using the choke. The effect of carb holder leaks can vary widely as the temperature of the cylinder head and/or carb holder changes. This is because the air leaks in between the mating surfaces through tiny cracks in the rubber, and as these cool or heat up the rubber on the carb holder mating surface may seal or not seal better against the cylinder head. In any event, this is worth checking because it is very easy to do, and if you find a leak it should be corrected.

Carb holders will eventually develop tiny cracks in the mating surfaces between the holders and the cylinder head that can cause them to leak at idle. These cracks cannot be seen with the carb holders in place. I suggest you try the following. Get the engine warmed up and temporarily set the idle as low as possible without killing the engine (lower than 900 rpm if possible). The lower the better because with the idle very low the slides are nearly shut and the vacuum inside the carb holders is at its highest. Then spray carb cleaner around the carb holders, especially where they mate with the cylinder head and where the carbs attach to them. Carb cleaner works best for this test as it doesn't leave an oily mess with WD40 or evaporate so quickly that it is not drawn into the leaks as can happen with propane or starting fluid (ether). If the engine dies or reacts to the carb cleaner, you need to replace the carb holders. Carb holder leak related problems are noticeable at idle but generally don't have much impact when riding because the throttle is open. If you find you need to replace the carb holders soak the screws with Kroil for a couple days before attempting to remove them, and use JIS standard, NOT Phillips, screwdriver bits, and this will greatly improve the odds that you will not break or strip a carb holder fastener as so many have done. Let me know if you need info on JIS bits, I have a good link for making your own at no cost. Ed

OK,
I'm going to recant my pod filter statement of being better than a stock air box. Your right about the stock box being better for a stock engine. I'm more likely to keep the stock box than not.

I just did a leak test on the carb holders. Engine warm and idling. No leak detected. No change in low 700-800 rpm idle. Throttle response however is a little sluggish.

Today upon cold start this time #4 cylinder was not getting as hot as the other three. Meaning the problem has moved from #2 to #4. Even #2 was a little slow to start heating up but soon matched the other two. This isn't the first time I noticed this. I suspected it at least once or twice before. Normally it's been #2 running cold till the engine warms up on choke at high idle. Once it starts getting warm the otherwise cold cylinder starts getting hot and the engine starts running fine. (on all four cylinders)
I actually wouldn't have been surprised to have found a cracked carb holder leak. Getting these carbs in and out from between rather stiff holders and air box hoses hasn't exactly been an easy task. Leak or not they do need to be replaced. I did order new air box hoses but not the holders. I blew this weeks budget on a clutch kit, plates, cable, the air box hoses needles and seats plus a few other parts. But what the hell ... I'll order sum tomorrow.
So ... I still think its something to do with the carbs. They're likely running lean on fuel at least during start up.

I'm not trying or meaning to sound like I'm being hard headed about this. I'm listening to what yall are telling me and trying to eliminate one thing at a time. I'm just not convinced I've eliminated the carbs as being the culprit yet.

Robert
81 KZ1000 LTD
All original.
15k miles.
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Re:10 amp Ignition fuse keeps blowing 03 Jun 2015 17:55 #675157

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Have you checked the IC igniter? If it has a short is can cause issues with intermittent fires, which makes the bike feel like it is running out of fuel. On my 750 the connection to the pulsing coils had become loose. It fired up and ran great, but would bog and blubber when riding.
Whip it like a mule!
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10 amp Ignition fuse keeps blowing 03 Jun 2015 19:35 #675163

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Guys , I couldnt stand it anymore so I had to register on this site to reply. Go to the Factory Pro ( make carb jet Kits ) web page they have the best CV carb tuning info you will find anywhere. I read it at least 10 times until it made sense and it works. I think I have seen other people refer to this info but couldnt find it. Now what I really wanted to talk about was the use of pod filters. I have been using them for 15 years on 2 different bikes a 82 KZ1000J with a 1075 cc Weisco pistons and Kerker header. and a 1981 GPZ1100 now an 1170 also with weisco pistons and kerker pipe. Both have BS34 carbs. The fuel injection on the GPZ was junke even when new thats why the changed to carbs.
It will take some patience to get there but I am here to tell you it can be done. I have also ran the GPZ with Mikuni RS36 flat slide carbs and it is crazy fast with them on but not easy to live with. I use the APE pod filters as they are the same as K&N but cost less than half price. Be sure to use oil on them yes I use the K&N oil but be sure to blow off the excess. One more thing is when I bought my Dyna coils from Z1 they told me I needed the 2.2 ohm grey ones better recheck that. Wish Dyna had some more info on there page.
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10 amp Ignition fuse keeps blowing 03 Jun 2015 21:08 #675172

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I suggest checking the spark cable ends. They can corrode and cause this kind of problem. Cut 1/4" off each end, put them back together and see what happens.
Steve
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