So, I've ordered a K1100 service kit from Motorworks and am fitting it. The spark plugs supplied are Bosch XR7LDC whereas the current ones are the XR5DC. A quick google finds this: [URL]http://euromotoelectrics.com/SparkPlugBMWAPPLICATION.html[/URL] Which suggests that the XR4CS, XR5DC and XR7LDC are all possible. Checking on the BMW service disk I've got the XR7LDC seems to be the correct one but isn't this a big range of heats?