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| Thread ID: 149849 | 2021-05-25 11:46:00 | Spark plug madness - what's the answer? | Agent_24 (57) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 1477377 | 2021-05-30 01:55:00 | Oh a weedeater one thing I forgot remove the exhaust muffler and check its clear and clean any carbon in the exhaust port. Some times they have a spark arrestor gauze bit like whitebait netting this blocks with carbon. Is the carb adjustable? does it have 3 screws marked T L and H? T is throttle ie idle rpm L is for the low mixture turn that for best RPM when idling and warm and reset idle. H give it full throttle and adjust for best RPM. Like I said before hook out the in tank fuel filter and blow it clean. In about 8 years and hundreds of 2 strokes I have had only 2 or 3 dud plugs. Obviously if the the plug is wet and oily it wont fire but that is not a dud plug just a dirty plug. The plug you have shown is not the right colour looks like too rich a mixture it should be a nice tan colour even on a 2 stroke. |
prefect (6291) | ||
| 1477378 | 2021-05-30 02:15:00 | I have no idea about that, but I have read that dirty plugs or plugs with a too-large gap need a higher voltage to fire and thus put more stress on the ignition coil, leading to premature failure. I was not sure if incorrectly using resistor/non-resistor plugs could do the same thing. . larger gap requires higher voltage, its generally only a problem is the coil can't generate enough voltage to jump. this can be a problem with resistor spark plugs. probably why they have it set to a small spark gap. |
tweak'e (69) | ||
| 1477379 | 2021-05-30 03:48:00 | I have no idea about that, but I have read that dirty plugs or plugs with a too-large gap need a higher voltage to fire and thus put more stress on the ignition coil, leading to premature failure. I was not sure if incorrectly using resistor/non-resistor plugs could do the same thing. Above more BS invented by someone's fantastical mind, fake news, total fabricated lies. The voltage is produced by a magnet in the flywheel passing through the windings of the coil, increasing the gap or putting a resistor in the plug can result in the plug not working but the voltage does not change therefore the coil wont be hurt. I have worked on hundreds and hundreds now and replaced about 3 coils. |
prefect (6291) | ||
| 1477380 | 2021-06-04 01:36:00 | I have no idea about that, but I have read that dirty plugs or plugs with a too-large gap need a higher voltage to fire and thus put more stress on the ignition coil, leading to premature failure. I was not sure if incorrectly using resistor/non-resistor plugs could do the same thing. Above more BS invented by someone's fantastical mind, fake news, total fabricated lies. The voltage is produced by a magnet in the flywheel passing through the windings of the coil, increasing the gap or putting a resistor in the plug can result in the plug not working but the voltage does not change therefore the coil wont be hurt. I have worked on hundreds and hundreds now and replaced about 3 coils. I don't have any statistical experience as you do but the concept is theoretically possible - if the peak voltage generated by an unloaded coil (no plug/bad plug/bad gap) were to exceed the maximum insulation resistance inside the coil itself, it could cause insulation breakdown and damage. Although, a well designed coil would hopefully have a peak voltage lower than whatever insulation is used inside it, therefore the problem should not occur, generally. But I suppose this theoretical plausibility is where that idea comes from. larger gap requires higher voltage, its generally only a problem is the coil can't generate enough voltage to jump. this can be a problem with resistor spark plugs. probably why they have it set to a small spark gap. That makes sense. Oh a weedeater one thing I forgot remove the exhaust muffler and check its clear and clean any carbon in the exhaust port. Some times they have a spark arrestor gauze bit like whitebait netting this blocks with carbon. Is the carb adjustable? does it have 3 screws marked T L and H? T is throttle ie idle rpm L is for the low mixture turn that for best RPM when idling and warm and reset idle. H give it full throttle and adjust for best RPM. Like I said before hook out the in tank fuel filter and blow it clean. In about 8 years and hundreds of 2 strokes I have had only 2 or 3 dud plugs. Obviously if the the plug is wet and oily it wont fire but that is not a dud plug just a dirty plug. The plug you have shown is not the right colour looks like too rich a mixture it should be a nice tan colour even on a 2 stroke. I did not think of that - I'll check the exhaust next time I go to use it. Yes the carburetor is adjustable and has the 3 screws. The user manual shows the adjustment procedure also. Thanks, I was not sure if the spark plug was OK or not. I thought it might be normal as there is the oil mixed into the fuel. I assume a rich issue would be a carburetor adjustment problem? Would that fit with the random stalling at idle? The air-filter looks clean and so does the fuel filter actually. Overall the machine seems well looked after, just old. The date in the user manual suggest it's from the late 1990s. |
Agent_24 (57) | ||
| 1477381 | 2021-06-04 04:05:00 | Forgot to mention, does it have a rubber primer nacelle anywhere, if so make sure that the small hole at the top of the nacelle is clear of dirt and debris as if it is blocked that will cause the engine to start and then repeatedly stall after running well for a short time. Normally with this system you give four pushes to the rubber primer if the machine hasn't been running for a while, before pulling the starter cord. |
zqwerty (97) | ||
| 1477382 | 2021-06-04 04:08:00 | Oh a weedeater one thing I forgot remove the exhaust muffler and check its clear and clean any carbon in the exhaust port. Some times they have a spark arrestor gauze bit like whitebait netting this blocks with carbon. I believe the spark arrestor gauze is required in dry climates not so much in NZ. It can be found in most if not all 2 stroke powered tools I have seen it on chainsaws as well as weedeaters and as Prefect has indicated can get carboned up particularly if your fuel has more oil in it than it should. Just as with the air filter if the exhaust system is restricted the engine cannot breath properly and will lack power as well as being difficult to start. |
CliveM (6007) | ||
| 1477383 | 2021-06-04 05:37:00 | Forgot to mention, does it have a rubber primer nacelle anywhere, if so make sure that the small hole at the top of the nacelle is clear of dirt and debris as if it is blocked that will cause the engine to start and then repeatedly stall after running well for a short time. Normally with this system you give four pushes to the rubber primer if the machine hasn't been running for a while, before pulling the starter cord. Haha my ancient weedeater bought second hand hand 4 years ago has had a perished nacelle since before it became mine, yet it starts and runs perfectly well. |
gary67 (56) | ||
| 1477384 | 2021-06-04 06:39:00 | As far as sparkplug colour at Hirepool we run 25:1 on everything and the colour is still tan as are my seagull outboards which run 10:1 the blackness would be from a rich mixture. You will get a carbon build up with oil burning but its tan coloured carbon. | prefect (6291) | ||
| 1477385 | 2021-06-04 07:21:00 | Yes well, it's if the nacelle is fully blocked that the problem happens not when it has holes in it, it just won't prime properly if it's torn/worn/ripped/perished, just require more pulls on the cord. | zqwerty (97) | ||
| 1477386 | 2021-06-04 23:12:00 | Just as with the air filter if the exhaust system is restricted the engine cannot breath properly and will lack power as well as being difficult to start . With the new spark plug it was very easy to start . Once going, it seemed fine and cut the grass well as I would expect . The only problem was dying twice at idle for no apparent reason . Forgot to mention, does it have a rubber primer nacelle anywhere, if so make sure that the small hole at the top of the nacelle is clear of dirt and debris as if it is blocked that will cause the engine to start and then repeatedly stall after running well for a short time . Normally with this system you give four pushes to the rubber primer if the machine hasn't been running for a while, before pulling the starter cord . Yes it has one but as mentioned earlier, that had been replaced with a brand new one by the previous owner so it's probably fine? It doesn't look dirty, anyway . As far as sparkplug colour at Hirepool we run 25:1 on everything and the colour is still tan as are my seagull outboards which run 10:1 the blackness would be from a rich mixture . You will get a carbon build up with oil burning but its tan coloured carbon . I guess I may have to run it for a while with the new plug and see what colour results . I used a 25:1 mixture as the manual stated, but who knows what mixture the previous owner was using . My granddad always put extra oil in his chainsaw mixture claiming more oil was better for it (but that seems debatable to me) . |
Agent_24 (57) | ||
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