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Re: Spark plug reach & piston contact

Thanks all. After reviewing pictures/the bike I now see it's over the valve, d'oh! I have no experience with these sidevalve engines. I assume there's no adjustment on valve lift then.

Thanks for confirming re the head skim, good shout I'll try a copper washer first. I see you can buy 1.2mm thick copper headgaskets on eBay which may help?

Re: Spark plug reach & piston contact

A 1mm solid head gasket would be the correct one to maintain the squish area inside the head to its correct dimensions...Spacing the plug is the way to go as long as it's not dissappearing up the threaded hole it screws into when fully tightened....Shrouding the plug too much will detrimentally affect combustion...
The only way you can have more valve lift than standard is if someone has fitted an alternative cam or modified the original.....Ian

email (option): ian@wright52.plus.com

Re: Spark plug reach & piston contact

Thank you Ian

Re: Spark plug reach & piston contact

Hi Iain,
Your problem is simple. The L29YC is an extended nose type, where the centre contact stands out further and thus the earth contact as well. Champion part numbers with a Y in them denote extended nose. The C denotes copper core. You need to go back to a conventional style plug, simple as that!

regards, Richard

Re: Spark plug reach & piston contact

Champion L86Y or Bosch W8AC. Both quite cheap from Tim Green
https://www.gsparkplug.com/ignition

Ron

email (option): ronpier@talk21.com

Re: Spark plug reach & piston contact

I wish I'd checked your replies a few days ago! I've just bought and installed a new plug and realised the 'extended projection' of the old one after comparing. D'oh. All sorted now, running loads better and without any copper washers/valve contact.

Thankyou all

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