Tech sticky from over on Triumph Rat

All things Triumph of all ages, the Classic & Vintage Section is full of knowledge and good info including the entry I've included here and I'm about to give it a go.Go pay a visit

09-05-2010, 10:27 PM	#1 (permalink)
Mr.Pete Moderator Moto Grand Prix Main Motorcycle: Rickman T120 Join Date: May 2010 Location: Victoria Australia Posts: 3,070 Other Motorcycle: T160,TR6	Bedding/Lapping Piston Rings. Here's the original method as it was described to me.No doubt there are alternatives.I've used this and it does work well,and gives better results than any conventional run-in procedure.I currently use a slightly different procedure. After you hone and re-ring,but before you fit the head: Mix BON AMI (original 1886 formula powder cleaner [yellow,not metallic gold container];the more modern "powder cleanser" formula has sweet smelling stuff and plant oils and does not have "1886 formula" on the container ) with thin oil,to make it like toothpase. With the pistons at BDC,cover the bores with this mixture. Rotate the engine 2 or 3 times and add more mixture. Do this until you've done 40 revolutions.At about 30 revolutions you'll see the mixture turn grey. Do not add any more mixture. Rotate the engine 10 more turns,wiping off as much mixture as you can. #Fit the head and start the engine.No slow idling,ride the bike.Alternate between heavy load (for a few seconds),and closed throttle. After about 20 minutes,do an oil change.This is mostly to get out the metal bedded from the rings,not so much for the BON AMI. - - - - - - - - - - - - - - - - - - - - - - - Thesedays,I lap the rings before I fit the barrel: Mix BON AMI with liquid detergent. *Check the ring gaps before you fit the rings on the piston.It's usually a good idea to have 30% bigger ring gap on the 2nd ring,compared to the top ring gap (say 0.003"-0.004" bigger).It helps the top ring seal,and reduces oil consumption. Fit the rings and piston into the bore with a spare conrod (or a stick with a hole) attached to the piston. Cover the bore above the piston with this mixture. Push the piston up and down the bore using slight rotation on each stroke. Add more mixture every 2-3 up/down cycles. After about 45 up/down cycles,pull the piston out and check ring contact.It should show continuous contact around the circumference,not necessarily across the full width. *Do not remove the rings from the piston. Rinse the piston/rings with water and blow dry. Rinse and dry the barrel. *Coat the barrel with WD40 or ATF.Wipe most of it off (as much as you can). Put one drop of oil on each side of the piston skirts,none on the rings. Assemble and run as previous method. Last edited by Mr.Pete; 06-09-2013 at 07:16 AM. Reason: "Check the ring gaps - - - - oil consumption."

09-06-2010, 02:43 AM