My GRiSO 1100 has 42.000 km on the clock and I have never changed the so called "internal" spark plugs (or even checked if they were tight...). How bad can this be? How hard is it to get to these things?
You need a thin walled socket to get them out as they are in very close proximity to the fins. Before attempting to remove them make sure you blow out the area around them vigorously with compressed air as all sorts of rubbish gets stuck around them, gravel, insect corpses etc. all of which will take the opportunity to drop down the plug hole into the cylinder if they aren't evicted before the plug is removed.
Having been left in for so long they are likely to be seized in pretty tight. When trying to remove them make sure you apply as little sideways force as possible try and keep the extension to the socket as close as coaxial to the plug. If the plug does snap chances are you'll need to take the head off to extract the threads from the head itself.
Also beware they are VERY easy to cross thread when re-installing. Read Pete's warning on keeping it axially perfect. Don't forget a smear of neverseez, copper-kote or similar before reassembly. If they get cross threaded, it is the same result as a snapped off plug - the head will need to come off. Good thing is it's a standard 10 mm thread (medium I think) and should be in any metric tap and die kit.
Don't ask how I know - well since you ask, on the Sport you need a 3/8" drive and not a 1/2" drive - the 1/2"drive hits the top frame rail on the Sport and the plug is not then axial to the hole. Perhaps a piece of plastic hose, fitted over the porcelain to get them started, before using the socket et al.
I bought it with the extension. It's pressed into the socket and swivels off angle. On the Sport, I was able to get it angled just past the frame rail. Worked very well. Then I used the old tubing trick to get the new plug started in straight.
Btw - The inner plugs cost me $40 bucks (CAN) a piece at a local auto parts shop. That stung.
I took my deepwell socket and threw it on a drill. Took it to my grinder wheel and spun it up with drill rotating. Was able to make the a thin wall socket in minutes. [You must be registered and logged in to see this image.]
Just a request for clarification, because I am a little confused now:
On a GRiSO 1100, the thread size of the 2 inner plugs is 10mm, while the thread size of the 2 outer plugs is 14mm. Is that correct?
Checking because in an other Ghetto discussion the NGK CR8EIX Iridium was suggested as a superior outer plug, but that plug comes in 10mm so is not suitable for the GRiSO 1100.
Yeah, you can use them for the inners, not the outers.
As I've said though you can't really go wrong with CR8EKB's. They're a twin electrode plug so they'll last near as dammit twice as long as a single electrode plug if you wish to push the boundaries a bit but really, being so cheap, you can just fling 'em more often.