dickv8 Posted July 21, 2008 Report Share Posted July 21, 2008 hello can any one help me ive got a 2006 txt 250 pro it developed a rattle whiche what i thaught was little end bearing but when i stripped the engine i found out that the barrel was worn by the exhaust port near the bottom of the stroke what can be done to rectifie this as i dont want to change the little end only to find it hasnt solved the rattle but i dont want to spend loads as im selling the bike can anyone help thanks everyone for taking the time to read this Quote Link to comment Share on other sites More sharing options...
jordi Posted July 21, 2008 Report Share Posted July 21, 2008 It may not be "worn", more likey a bit of aluminium pck up from the piston. Try rubbing it out with some very fine wet & dry, it will probably just disappear. Fit new rings while you have the barrel off as well. good luck. Quote Link to comment Share on other sites More sharing options...
dickv8 Posted July 21, 2008 Author Report Share Posted July 21, 2008 when i look at the barrel liner it looks worn around the exhaust inlet and i have heard that they are nickel plated and theres no liner how do i resolve this issue do you think that a new set of rings and little end and gudgeon pin will cure and should the barrel have these signs of wear thanks Quote Link to comment Share on other sites More sharing options...
peterb Posted July 21, 2008 Report Share Posted July 21, 2008 Hello dickv8, It would be really unusual for an 06 bike to already have a worn barrel, how have you determined the wear? It would not be easy by sight alone. Use an internal micrometer at various points up the barrel between the ex and inlet port, these are the areas that would wear from use, determine the amount of taper in the bore, should be less than 1.5 thou. If you want to change the barrel, you may be able buy exchange barrel/piston, or have your barrel replated and fit a new piston. If it were me, and the bore looked/measured ok, I'd fit a new piston, one letter up from std. ("A" is normally fitted, try a "B" piston, slightly larger skirt dia.) It's the piston that usually wears/distorts and creates the rattle, on later motors. Bye, PeterB. Quote Link to comment Share on other sites More sharing options...
dickv8 Posted July 21, 2008 Author Report Share Posted July 21, 2008 thanks for the info im only going on looks at the moment but i noticed the the barrel is marked a and the piston marked b can i go to a c piston thanks Quote Link to comment Share on other sites More sharing options...
jse Posted July 21, 2008 Report Share Posted July 21, 2008 when i look at the barrel liner it looks worn around the exhaust inlet and i have heard that they are nickel plated and theres no liner how do i resolve this issue do you think that a new set of rings and little end and gudgeon pin will cure and should the barrel have these signs of wear thanksthanks for the info im only going on looks at the moment but i noticed the the barrel is marked a and the piston marked b can i go to a c piston thanks It would depend on the wear of the cylinder. The piston "Alpha sizes" usually vary .005mm or about .0002" from letter to letter. Your bore is Nikasil coated, which is silicon carbide particles in a nickel matrix, so in effect your bore is nickel coated, but the nickel is the "glue" that holds the ceramic particles to the bore wall (your piston is also infused with silicon carbide particles, usually 17-22%). I'd follow Peter's advice and do some measurements. If you're not sure how, take it to a good mechanic, who will use a "dial bore indicator" on it and get a direct measurement of taper and bore diameter. You have to keep in mind that the required piston/cylinder clearance will be at the "tightest" spots, which is usually the skirt of the new piston and towards the bottom of the bore, not the top. We're just making an educated guess according to your descriptions, so it might be a good idea for someone with some engine experience to take a good look at it as it might save you some money in the long run. Jon Quote Link to comment Share on other sites More sharing options...
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