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x Mark misfires
#1
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tim4
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tim4
I have a x mark with 25 horse kal engine on it. I cleaned the carburetor and replaced the coil on the side that was not firing and adjusted the valve clearance. it fires on high speed but it miss fires on slower speeds. The compression is 150 on the side with the miss fire.
#2
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Rivets
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Rivets
The first thing I would do is to install an inline spark tester, You must first identify if the misfire is caused by an ignition or fuel problem. If the spark is steady at all speeds, you have a fuel problem. If the spark in not steady at all speeds, ignition problem. Let us know what you find and then we can give you a better idea as to how to proceed.
#3
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tim4
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tim4
The first thing I would do is to install an inline spark tester, You must first identify if the misfire is caused by an ignition or fuel problem. If the spark is steady at all speeds, you have a fuel problem. If the spark in not steady at all speeds, ignition problem. Let us know what you find and then we can give you a better idea as to how to proceed.
The first thing I would do is to install an inline spark tester, You must first identify if the misfire is caused by an ignition or fuel problem. If the spark is steady at all speeds, you have a fuel problem. If the spark in not steady at all speeds, ignition problem. Let us know what you find and then we can give you a better idea as to how to proceed. It is getting good spark. On idle it is running on one cylinder and when I pull the choke out all the way the cylinder that was not firing fires. So it is probably a air leak somewhere.
#4
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Rivets
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Rivets
If you are assuming there is an air leak, then remove the blower shroud and spray carb cleaner around all gasket surfaces, while engine is running, to locate the leak. I’m also assuming you tested for spark using an inline spark tester, at different engine speeds. If not, how did you preform the tests?
#5
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tim4
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tim4
I grounded the sparkplug and the spark was good. I will check for air leaks thanksIf you are assuming there is an air leak, then remove the blower shroud and spray carb cleaner around all gasket surfaces, while engine is running, to locate the leak. I’m also assuming you tested for spark using an inline spark tester, at different engine speeds. If not, how did you preform the tests?
#6
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Rivets
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Rivets
That way of checking for spark only you tell you if you have spark at cranking speed, so in your case tells us nothings about the ignition system under load.
#7
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tim4
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tim4
I put a new coil on it and I believe it is running too rich. There was no air leak and at a idle the air filter hold down assembly behind the choke gets fuel in it but past idle the fuel disappears from that part but the engine back fires so I think it is carburetor.That way of checking for spark only you tell you if you have spark at cranking speed, so in your case tells us nothings about the ignition system under load.
#8
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Rivets
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Rivets
Ok, I’ll try one more time. From your posts you are making assumptions, not testing, just throwing parts at it. I’m really wondering if you know what you are doing. First, you say one side is not firing at low speed, but how did you come to this assumption? Second, you threw a new coil at it but never tested the old one, did you set the air gap properly? Third, you said you cleaned the carb, how did you do that? Did you really pull it apart and make sure all jets were open, passageways clean, float level set properly and reassembled correctly with new gaskets? You state the air filter assembly is behind the choke. I’m sorry the air filter should be in front of the choke on every engine I’ve ever worked on and if it is getting full of fuel, the float needle is not operating properly. Now if you really want any of us to help you, you must start over by posting all engine numbers so we have a clue as to what engine you have. You must tell us exactly what you have done to this point, including why and how. If we make assumptions by using what you have told us so far, we are only guessing and assuming. You do know know that when we ASSUME we make an (ASS out of U and ME)
#9
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tim4
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tim4
First of all I had a friend help me clean the carburetotr and he cleaned the jets and checked the float. We checked the spark of the old coil by cranking the engine over and the spark he said was weak. I set the air gap of the new coil and we pulled the wire off the spark plug at idle and no difference. gI was referring to the housing that screws to the carburetor which is located behind the choke..Ok, I’ll try one more time. From your posts you are making assumptions, not testing, just throwing parts at it. I’m really wondering if you know what you are doing. First, you say one side is not firing at low speed, but how did you come to this assumption? Second, you threw a new coil at it but never tested the old one, did you set the air gap properly? Third, you said you cleaned the carb, how did you do that? Did you really pull it apart and make sure all jets were open, passageways clean, float level set properly and reassembled correctly with new gaskets? You state the air filter assembly is behind the choke. I’m sorry the air filter should be in front of the choke on every engine I’ve ever worked on and if it is getting full of fuel, the float needle is not operating properly. Now if you really want any of us to help you, you must start over by posting all engine numbers so we have a clue as to what engine you have. You must tell us exactly what you have done to this point, including why and how. If we make assumptions by using what you have told us so far, we are only guessing and assuming. You do know know that when we ASSUME we make an (ASS out of U and ME)
#10
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txmowman
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txmowman
What type of spark tester? If you use a gap type tester, the standard for small engines is 1/4". If the coil will jump the gap, the coil is fine. Also, connect the clamp of the tester to the rocker cover bolt, not the spark plug itself. There is a diode in the coil. Unless you remove the ground wire from a coil, you might replace the wrong coil. Meaning, a failed diode in the #1 coil will make the #2 coil not fire. But, #1 is the failed coil.
#11
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txmowman
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txmowman
Also, if your compression gauge is accurate, 150 compression is high. What did you adjust the valve gap to? How did you adjust? You wrote "it fires at high speed but misses at low speed", what does this mean? A coil has no determination of high/low speed. Do you have spark the whole time, but the engine has a miss?
#12
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tim4
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tim4
What type of spark tester? If you use a gap type tester, the standard for small engines is 1/4". If the coil will jump the gap, the coil is fine. Also, connect the clamp of the tester to the rocker cover bolt, not the spark plug itself. There is a diode in the coil. Unless you remove the ground wire from a coil, you might replace the wrong coil. Meaning, a failed diode in the #1 coil will make the #2 coil not fire. But, #1 is the failed coil.The bad coil was on the right side. I took the carburetor apart again and dirt got in the needle and seat so I cleaned it. It does not leak now but still acts like it is starving for fuel so the owner brought it to another shop for diagnosis.
#13
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hlw49
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hlw49
Still have not posted the model and spec no. what type of carb it is single or two barrel. If you have no air leaks and it is a two barrel carb one side of the carb can be stopped up as each barrel feeds its side on the engine. If it is a two barrel one of the welch plugs over the idle clusters can be missing.First of all I had a friend help me clean the carburetotr and he cleaned the jets and checked the float. We checked the spark of the old coil by cranking the engine over and the spark he said was weak. I set the air gap of the new coil and we pulled the wire off the spark plug at idle and no difference. gI was referring to the housing that screws to the carburetor which is located behind the choke..
#14
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tim4
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tim4
Still have not posted the model and spec no. what type of carb it is single or two barrel. If you have no air leaks and it is a two barrel carb one side of the carb can be stopped up as each barrel feeds its side on the engine. If it is a two barrel one of the welch plugs over the idle clusters can be missing.
I have to get someone to read the numbers on the engine, I dcan't see it. It is a 2 barrell carburetor.Still have not posted the model and spec no. what type of carb it is single or two barrel. If you have no air leaks and it is a two barrel carb one side of the carb can be stopped up as each barrel feeds its side on the engine. If it is a two barrel one of the welch plugs over the idle clusters can be missing.