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Stuckagain

Sparks plugs

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Yes, I know - there's other trails on here about plugs, but not quite specific enough for me.

Not sure my bike is running as it should - 1993 Beta Zero Gara 260. It didn't have a standard spec plug in it when I got it. I put the recommended standard one in - B8ES - thinking I was doing the right thing, but it feels like it's running hot and/or weak, and idle eventually fades when I'm getting stuck in up at Inch Perfect. Riding it when I first got it it did idle no problem with a Champion RN7YCC in it, and didn't feel like it was getting hot - fan rarely kicked in. But is that plug much different from the B8ES? The Champion has a far bigger electrode. Should I change back from the NGK B8ES to that plug, or another plug? If so which one? And should I be running it on super-unleaded...?

Plug is a teeny bit dark after running it around in sea-level Cheshire, and doesn't feel like it's running weak. Do I need to tweak the mixture screw and/or change the plug when I'm 1500 feet up in the Lancashire hills?

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I don´t know much about NGK plugs but I think N8ES is a non projected plug. A projected would be called BP8ES.

A Champion equivalent to N8ES would be N3 or N3C. Even if they are called equivivalent the heat range may differ slightly.

RN7YCC is a  projected resistor plug and is supposed to be little hotter then N8ES. A non resistor plug would be N7YC(C)

You´ll have to find out what sort of plug your ignition and engine require, resistor /non resistor and projected/non projected. As long as the plug doesn´t hit the piston crown I would use a projected plug and even if your ignition is made for non resistor types it may work well with a resistor type plug.

I would try a N9YC(C) which is slightly hotter than the mentioned types, or RN9YC(C) if a resistor plug is prefered. In my Bultaco 199A I use N11YC which is the next step hotter. I think NGK should be BP5ES (N9YC) and N11YC is close to BP4ES

As the RN7YCC didn´t hit the piston I think N9YC also would clear the piston crown but you´ll have to look, for safetys sake. Only applies for projected types of all brands.

The idle mixture screw only affects the idle. My guess is your plugs have been too hard/cold. A softer/hotter plug would clean better.

When you have find the correct plug you don´t have to replace it for normal altitude changes. Only of you suddenly start to ride very hard or vice versa.

I f you go for Champion plugs, try to find NOS with big electrodes. I am a strong believer that they were better and lasts longer.

As always: Start with what the manual says but your engine is nearly 20 years old and petrol and spark plugs have changed during time.

Led in petrol  had to go when the catalytic cleaning came but all of us (who are older than 20) have led in our bodies from led-petrol burning.

You may use alkylate petrol like Aspen for safety and health but it will be difficult read the spark plugs. The only downside is that it costs more.

https://www.sparkplug-crossreference.com/

https://aspenfuel.co.uk/

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