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Honda Wave frequent spark plug failures


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On 5/5/2021 at 9:31 PM, kickstart said:

That still looks a bit black to me especially for a four stroke .

If you can ,try and get a compression  test done ,Google for the correct results ,I doubt if the guy doing the test will know .

Are you sure the engine is not using any oil .

I know it is a new carb , but what are the carb settings, try the pilot jet screwed out 1, 1/4-1, 1/2 turns ,check the height of the needle ,Google should tell you the correct settings for the carb .

A problem I have had with more than one engine , carb  float height that being wrong will not help .

Someone told me a long time ago ,the plug is at the end of the line ,look at things back from the plug .

 

14 hours ago, alx123 said:

That's a foul plug right there, it's either youre running rich or your piston ring needs changing. 

 

Maybe a simple carb tuning will help. 

Thanks for your replies and all those above.

 

That was a used plug I put in so not the perfect example and the pic is a bit darker than the actual plug but I do wonder about the deposits already on it. As mentioned above I just put in a new plug so I'll run that for a while and check its condition when I pull it out to do a compression check with the tester I'm waiting on to be delivered. In the meantime I won't fiddle with anything else just yet.

 

kickstart:

Everything was replaced on the electrical side of the plug, CDI unit, coil and wire, spark plug connector. As you suggest the problem is likely on the fuel/compression side of the plug.

 

It doesn't appear to be burning any oil, never see it go down on the dipstick but then again I've never monitored the exact level on the dipstick.

 

Wondering if fouling can ruin a plug I searched and came across this old forum post on another site:

https://www.houzz.com/discussions/1635586/gas-fouling-a-new-spark-plug-and-bringing-it-to-ruin

 

>It isn't just the fact that the plug was "soaked in gas" that ruins it. It is rather something that happens to the insulator from running the engine in an in an extreme rich condition. The insulator gets a microscopic crack allowing the spark to jump through to ground. In other cases the rich condition forms heavy black carbon on the insulator thus conducting the spark to ground. This condition takes longer to happen. The first condition can happen in seconds or minutes. I have seen this happen personally many times on brand new engines. The plugs look perfect when removed but when tested with a pressure tester they will not fire. No amount of cleaning could ever make those plugs fire. The problem happened with multiple brands of engines and plugs. When in doubt...replace the plug. You cannnot judge a spark plug by looking at it every time."<

 

That bold text does sound like what's going on with my plugs as the spark goes off to the side of the electrode towards the threads. Maybe there are deposits down inside that I can't reach that are causing the plug failures.

 

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Yes , there are quite a few things that can damage a plug and it's hard to see it or via simple tests that we do, so a new plug is always a good/simple/cheap approach....👍

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5 hours ago, KeeTua said:

 

Thanks for your replies and all those above.

 

That was a used plug I put in so not the perfect example and the pic is a bit darker than the actual plug but I do wonder about the deposits already on it. As mentioned above I just put in a new plug so I'll run that for a while and check its condition when I pull it out to do a compression check with the tester I'm waiting on to be delivered. In the meantime I won't fiddle with anything else just yet.

 

kickstart:

Everything was replaced on the electrical side of the plug, CDI unit, coil and wire, spark plug connector. As you suggest the problem is likely on the fuel/compression side of the plug.

 

It doesn't appear to be burning any oil, never see it go down on the dipstick but then again I've never monitored the exact level on the dipstick.

 

Wondering if fouling can ruin a plug I searched and came across this old forum post on another site:

https://www.houzz.com/discussions/1635586/gas-fouling-a-new-spark-plug-and-bringing-it-to-ruin

 

>It isn't just the fact that the plug was "soaked in gas" that ruins it. It is rather something that happens to the insulator from running the engine in an in an extreme rich condition. The insulator gets a microscopic crack allowing the spark to jump through to ground. In other cases the rich condition forms heavy black carbon on the insulator thus conducting the spark to ground. This condition takes longer to happen. The first condition can happen in seconds or minutes. I have seen this happen personally many times on brand new engines. The plugs look perfect when removed but when tested with a pressure tester they will not fire. No amount of cleaning could ever make those plugs fire. The problem happened with multiple brands of engines and plugs. When in doubt...replace the plug. You cannnot judge a spark plug by looking at it every time."<

 

That bold text does sound like what's going on with my plugs as the spark goes off to the side of the electrode towards the threads. Maybe there are deposits down inside that I can't reach that are causing the plug failures.

 

Fitting a new carb to an old engine, is not the same as a new carb ,new engine ,setting will not be the same.

Try adjusting the pilot jet/mixture screw, tightening the screw weakens the air /fuel mix, so decreasing the amount of fuel flowing to the engine ,should help with the plug .

Try 1-1 1/4 turns out ,when the screw is screwed right in , most cabs are 1 1/2-1  3/4 turns out .

But I would still say an old bike the engine will be getting worn , and it will foul the plug ,a lower compression on the engine worn rings,  piston, valves /guides, will not give you a clean burn at the plug ,resulting in a black plug ,un-burnt fuel, how many Kilometres has it done ,if the tripe meter is working ,has the oil been changed regular .

 

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On 5/7/2021 at 8:37 PM, kickstart said:

Fitting a new carb to an old engine, is not the same as a new carb ,new engine ,setting will not be the same.

Try adjusting the pilot jet/mixture screw, tightening the screw weakens the air /fuel mix, so decreasing the amount of fuel flowing to the engine ,should help with the plug .

Try 1-1 1/4 turns out ,when the screw is screwed right in , most cabs are 1 1/2-1  3/4 turns out .

But I would still say an old bike the engine will be getting worn , and it will foul the plug ,a lower compression on the engine worn rings,  piston, valves /guides, will not give you a clean burn at the plug ,resulting in a black plug ,un-burnt fuel, how many Kilometres has it done ,if the tripe meter is working ,has the oil been changed regular .

 

It has 45K km on it and considering what my wife has told me and the overall condition I would say that engine oil changes weren't regularly neglected.

 

I plan to run it for about 1-200km and then check the condition of the new plug I just put in and do a compression test. In the past I only pulled the plug out once it was failing and running crappy so they weren't good examples. I want to see how the color is when its running sweet before I start adjusting things. If the compression is acceptable (120psi or better?) but the plug is too dark then I'll make the carb adjustment you recommend.

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  • 2 weeks later...
On 5/7/2021 at 8:37 PM, kickstart said:

Try 1-1 1/4 turns out ,when the screw is screwed right in , most cabs are 1 1/2-1  3/4 turns out .

Took the Wave for short ride to get it up to operating temp and pulled the new spark plug with about 100km of use on it. Checked compression which was 135 psi. The electrode is definitely too dark and some black deposits are already forming on the top edge of the threads similar to the plug image I posted before and maybe a little oil on the threads themselves. With good compression like that I would guess there is very little oil getting by the rings. Maybe oil is getting in the cylinder via worn valve guides?

 

I adjusted the carb idle mixture screw to 1 1/4 turns out as suggested.

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