Spark plug recommendations?

Information relating to the Matchless G12 or AJS Model 31 650cc twin
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Spark plug recommendations?

Postby mjf65 » Tue Jun 04, 2019 2:37 pm

I think my bike deserves new plugs as I've no idea how old they are? Currently have Bosch W5CC fitted.

Thanks.

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Re: Spark plug recommendations?

Postby dave16mct » Tue Jun 04, 2019 2:40 pm

Champion N5C.
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Re: Spark plug recommendations?

Postby mjf65 » Tue Jun 04, 2019 7:15 pm

Thanks Dave, is it worth investing in an irridium plug? I'm finding cold starting a problem so anything that would help the process would be good.

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Re: Spark plug recommendations?

Postby dave16mct » Tue Jun 04, 2019 7:31 pm

I've never bothered with them. I only know one member who uses one in a single and rates it. Most seem to think they're a waste of money. You don't say what your bike's ingition system is, magneto, coil or electronic?
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Re: Spark plug recommendations?

Postby mjf65 » Tue Jun 04, 2019 8:37 pm

Magneto ignition. I've got Bosch plugs fitted at the moment probably 15 years old which might account for the cold starting problem plus I've only been starting the bike once a week, I'll give it a go with the stndard Champions and see what it's like.

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Re: Spark plug recommendations?

Postby dave16mct » Wed Jun 05, 2019 10:23 am

For a magneto set them to 22 thou and check you have non-resister plug caps. You will find the best position for the adv/retard lever by (painfully) setting to full advance then gradually retard until it stops trying to kick you over the shed! That's then the position to set it to for best starting.
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Re: Spark plug recommendations?

Postby alanjennings » Wed Jun 05, 2019 4:51 pm

22 thou? Seems rather a wide gap?
Alan [Morini] Jennings

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Re: Spark plug recommendations?

Postby dave16mct » Wed Jun 05, 2019 6:39 pm

You're not getting mixed up with the points gap are you Alan? What do you set your plug gaps to? I usually set my plug gaps to 22 thou on the twin with Magneto.
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Re: Spark plug recommendations?

Postby ajscomboman » Wed Jun 05, 2019 7:11 pm

22 thou for a magneto and 25 thou for coil that's what settings I use.

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Re: Spark plug recommendations?

Postby raffles » Wed Jun 05, 2019 7:15 pm

Allan is probably ok if he can get a whisker through
Tony

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