Spark Plug Cleaning

Soak in cheap white vinegar. Brass wire brush lightly.

kerinorton said:

I like the comment about getting the mixture right. I regularly get 60+ mpg out of mine. Is the mixture about right.

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It’s probably about right, between 1/8 throttle and 1/2 throttle, where you’re doing your running. That is, throttle slide cutaway and needle position are correct, or at least not rich.

It could still be rich at idle and that can foul your plugs without having much effect on mpg.

Sometime in the last 20 years plug manufacturers realised that with the widespread use of computer controlled fuel systems spark plugs ran clean. Insulators no longer needed a hard protective finish. Insulators can now absorb oil and carbon in our old tech motors. Its not easy to clean now. Replacement is more reliable . What sort of idiot rides an old bike anyway?, They should be in a museum, with the bikes!!!.

just curious - how are you folks reading plugs to determine your mixture? by no means an expert, but i'm thinking, for best overall (street applications), you need to read plugs after a steady-state cruise at 1/4-1/2 throttle with minimum idle time. ????

joe czech said:

just curious - how are you folks reading plugs to determine your mixture? by no means an expert, but i'm thinking, for best overall, you need to read plugs after a steady-state cruise at about 1/2 throttle with minimum idle time. ????

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There’s no “overall.”

You follow the Amal tuning procedure, at the respective throttle positions.

There is no idle time when doing plug readings at throttle positions other than when you’re checking the idling mixture. You switch off the ignition while running with the throttle at the position you’re checking mixture at.

If there is soot on the plug, it’s rich.

Triton Thrasher said:

There’s no “overall.”

You follow the Amal tuning procedure, at the respective throttle positions.

There is no idle time when doing plug readings at throttle positions other than when you’re checking the idling mixture. You switch off the ignition while running with the throttle at the position you’re checking mixture at.

If there is soot on the plug, it’s rich.

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not trying to be argumentative and I agree, but that's my point. since most riding is done at the 1/8-3/4 throttle position, there has to be that sweet spot to read your plugs. the pilot circuit is easy enough to adjust, the throttle cutout, unless you're getting into super-tuning, is pretty much fixed, so the needle and clip position and it's relationship to the main jet, IMO, dominate carb tuning - or from the tuning guide, the 1/4-3/4 throttle position. that's kind of what I was referring to as best overall, or where i'd focus carb tuning. that's where most adjustments are going to be with the needle clip. this is all based on street riding and pretty much a factory configured stock bike - or am I out in left field? again, i'm thinking if you read your plugs at a steady state, quarter to half throttle - that's the "best overall" and should be the focus of your tuning. if you get that right, you're pretty much home free. IMO, everything else are minor adjustments.

Everyone has their own little ways of tuning and also of describing how they do it.

Yes, needle position often dominates open road riding.

Main jet is important because you don’t want sudden weak mixture when you use full throttle. That can cause serious problems. You don’t want a rich mixture making it blubber instead of accelerating, either.

If you get idle mixture and cutaway size right, your bike has at least some chance of being manageable in slow traffic.

Triton Thrasher said:

Everyone has their own little ways of tuning and also of describing how they do it.

Yes, needle position often dominates open road riding.

Main jet is important because you don’t want sudden weak mixture when you use full throttle. That can cause serious problems. You don’t want a rich mixture making it blubber instead of accelerating, either.

If you get idle mixture and cutaway size right, your bike has at least some chance of being manageable in slow traffic.

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agree. one thing I might add - the factory pretty much knows what the main jet and throttle cutout size for most conditions. I usually find with most things, it's not wise to try to out think the factory (stock configuration). if your at 1/2 throttle cruise, and you crack the throttle wide open - as long as the bike pulls and does not fall flat on it's face, you're pretty good with the main jet. under 1/4 throttle - with the throttle slide cutout - not much adjustment other than pilot screw adjustment. the zero to 1/8-1/4 throttle is pretty much a narrow band, fixed without adjustment.

joe czech said:

agree. one thing I might add - the factory pretty much knows what the main jet and throttle cutout size for most conditions. I usually find with most things, it's not wise to try to out think the factory (stock configuration). if your at 1/2 throttle cruise, and you crack the throttle wide open - as long as the bike pulls and does not fall flat on it's face, you're pretty good with the main jet. under 1/4 throttle - with the throttle slide cutout - not much adjustment other than pilot screw adjustment. the zero to 1/8-1/4 throttle is pretty much a narrow band, fixed without adjustment.

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Exactly.
Hence the first step of tuning is, ensure everything is in good condition and on standard settings. Unless you live very high up, or use strange fuel, or have a modified set up, it should be fine.

My first job in engineering was at the Toyota factory in Durban, South Africa. The head of R&D did a test were they ran the same plugs for something like 250 000km. Used a glass blaster to clean them and a small file to keep the edges sharp. Eventually he stopped because there was no more metal left on the center electrode, but the vehicle worked perfectly.

I have a small blaster unit which I use about once a year. New plugs here are fairly expensive, so it's worth while I feel.

Agreed: standard settings on a standard bike, subject to some experiment if you’re keen.

joe czech said:

just curious - how are you folks reading plugs to determine your mixture? by no means an expert, but i'm thinking, for best overall (street applications), you need to read plugs after a steady-state cruise at 1/4-1/2 throttle with minimum idle time. ????

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No idle time. De-clutch and shut down, coast to the side of the road, please pick a safe place, wait a few minutes for heat soak to peak and begin to dwindle, remove plugs and read. Be prepared to be dealing with HOT parts.

Best

Norton Bob. wrote "
Sometime in the last 20 years plug manufacturers realized that with the widespread use of computer controlled fuel systems spark plugs ran clean. Insulators no longer needed a hard protective finish. Insulators can now absorb oil and carbon in our old tech motors. Its not easy to clean now. Replacement is more reliable . What sort of idiot rides an old bike anyway?, They should be in a museum, with the bikes!!!."

A agree. That's our problem now days, so buying expensive plugs, with modern insulators could be a waste of effort. I have accepted the fact that the plugs will foul up, and I know they have because the bike gets hard to start once in a while. I then remove the plugs, wash them in petrol then sand blast them. They then work well until the next time which could be Year away. I live in a country town so whenever the bike is started , i am usually up to highway speeds fairly quickly. My plugs eventually foul up though. It idles reasonably well, but I never leave it idling. As it is economical, I have to presume the mixtures are correct for the way I ride it. BP7ES / N7Y plugs were the recommendation for the riders of these bikes in the 70's, but us riders who are in our 60's, they are too cold. As for BP8ES, they are probably too cold for racing!!!. I run N9Y plugs now and sometimes put N7Y plugs in for long trips, like Norton Rallies. They are always dark looking on the insulators when they have fouled, but it does take a fair amount of riding. The bike can use a bit of oil on long trips but Never too much. A ride from Wellington to Auckland one time showed no oil use. A ride from Kerikeri to Mahia and back to Welsford did use oil though. I had forgotten to check it when in Mahia so it was barely touching the dip stick when it was checked.
Dereck

Sandblasting plugs can leave particles of sand stuck between the insulator and the plug body.I like the idea of soda blasting for that reason.

Ever since they removed the lead from gasoline, it is more difficult to read the mixture. This is so even with the use of a proper magnified spark plug flashlight With the advent of electronics and oxygen sensors, the art of reading spark plugs is near dead.

Sandblasting plugs can leave particles of sand stuck between the insulator and the plug body.

I trained as an auto engineer so very aware of that.

Back in the late 60s early 70s when my brother and I were still at school, we were messing around with clapped old 2 stroke Villiers engined bikes up the woods, they regularly oiled the plugs.
Now our old dad had a lodge plug cleaner, that he'd probably inherited from his dad. this consisted of something that looked like the old metal cigar tube one used to get, but it was full of straight wire strands about 4 inches long, you screwed the plug into the open end and shook it. It was excellent and I wish I still had one, ive occasionally looked on ebay but never seen one.
Terry

Myford said:

Back in the late 60s early 70s when my brother and I were still at school, we were messing around with clapped old 2 stroke Villiers engined bikes up the woods, they regularly oiled the plugs.
Now our old dad had a lodge plug cleaner, that he'd probably inherited from his dad. this consisted of something that looked like the old metal cigar tube one used to get, but it was full of straight wire strands about 4 inches long, you screwed the plug into the open end and shook it. It was excellent and I wish I still had one, ive occasionally looked on ebay but never seen one.
Terry

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I have one, vintage unknown, branded: 'Norwood' Instructions have worn off/faded over the years, but I seem to remember they recommended using a bit of petrol in it too. I use Redex but it's more a novelty now...

As Myford has mentioned about old 2 strokes.

Back in the good old days we used to be frightened into thinking too hot a plug would burn a hole in a piston. I was always buying the recommended spark plugs for my 150 twin Suzuki. They fouled up too quickly. I took the bike home for Christmas one time and my father told me to fit hotter plugs. He cleaned up all the "recommended ones for me and told me to use them only when I was on a long trip, but that the hotter plugs would be ok left in. I think he wanted to preserve my pride by saying those others could still be used. After all, I was a poor student then, living away from home.

Dereck

kerinorton said:

As Myford has mentioned about old 2 strokes.

Back in the good old days we used to be frightened into thinking too hot a plug would burn a hole in a piston. I was always buying the recommended spark plugs for my 150 twin Suzuki. They fouled up too quickly. I took the bike home for Christmas one time and my father told me to fit hotter plugs. He cleaned up all the "recommended ones for me and told me to use them only when I was on a long trip, but that the hotter plugs would be ok left in. I think he wanted to preserve my pride by saying those others could still be used. After all, I was a poor student then, living away from home.

Dereck

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Don‘t leave us hangin’....

Was the hotter plug fine ?

Did it hole a piston ?

in my poorer youth. i used to burn over a gas stove then emery cloth in the gap. never used a wire brush. now i just buy another pair.