i have a dt 125 and have just changed the head,piston and rings,when i put the engine back together and started the bike it is making a distinctive tapping that is coming from the head what could this be and could it cause damage to my bike? thanks

phillip ed, March 2010

dnt ride your bike,, ensure u put the same size piston in . what came out . as morse dt's have been bore'd , 0.25mm rebore would run with a standard piston .. but will chew ure rings wen warm ...

tom, August 2011

when you say head piston and rings do you mean barrel, piston and rings?

adam bike doctor, March 2010

well it could be either the piston hitting the head gasket as the gasket is meatal,or it could be the small end bearing work which is common on dt's they break up or it could just be piston slap .is the piston and barrel new or secondhand?and does it tap more on the overun at about 3-4000 prm,so once you have revved it to say 6000rpm and then let go of the throttle does it slap at 3-4000rpm.then go a bit quiter but still tap a little bit?if so then its piston slap.dont worry about the noise if its piston slap it may be a fraction slower but you wont seize it in a hurry.:)

adam bike doctor, March 2010