barney01 wrote:Gary, first thing to note is that compression testers vary in readings it really depends on how much you spend on the gauge! However i think its more important that the readings are of similar value. With regard to the rings, they are supposed to move during normal operation and yes they can stick in the grooves. I would definately clean the piston crown and exhaust ports as well as cleaning those grooves. A new set of base and head gaskets would make it a good job too. You can using your fingers feel the inside of the bore at the front and top of the stroke see if there are any ridges. If there are then it may be time for a rebore.
Another way is to remove the piston rings insert them into the bore and measure the gap between the ends of the rings at the top, centre and bottom of the stroke.
Thanks Barney for your reply. I shall take a look Saturday morning as i think the rings are gummed in. I removed the plugs earlier to do the compression test and there was a fair amount of crud on the plugs just around the rim which i suspect to be carbon deposits.
This would all add up really as when i bought the bike it had no V5 and no number plate, so i built the bike on an absolute minimum budget in case i had dropped a bo11ock buying it. This basically meant it got thrown back together with minimal work on certain things. From memory i probably didnt clean up the carbon deposits then, so given i have done a couple of thousand miles, plus the original 18000 then this may well be the case and a de-coke will be well over due.
PS the compression tester was only 14 quid so probably not the best but better than none
Thanks again ...Gary