Sparks Posted March 26, 2012 Share Posted March 26, 2012 Hello everyone i have joined your great forum today after browsing posts this weekend.i have dt125r which I am repairing for my 17 year old son.Sam! Having problem with powervalve positioning and type. My barrell and head is type BN Have fitted barrell piston and head from spare engine . New gaskets used.piston and bore is+1.5mm. My problem is the powervalve when set in locked position has rubbed on side of piston and caused rings to Jam in grooves. Now I need a new piston Is this because the barrel has been bored out +1.5mm? ! Does anyone know if there are different powervalve sizes . I fitted powervalve from barrell and head code MB which would not fit in unless modifying. Have tried 180' but it in open position .have got 2 types now , one has diamond shape on end (4 position ) other has 2 flats (2 positions ) both have location pin on pulley wheel but in different positions. Any advice on set up position please ????????Would like power valve open. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted March 26, 2012 Moderator Share Posted March 26, 2012 Hi sparke so are you using the one with the diamond shaped connection? Link to comment Share on other sites More sharing options...
Moderator Airhead Posted March 26, 2012 Moderator Share Posted March 26, 2012 ok its late so gotta go, have a look here for setting up the diamond shaped on...post~ #31 with 3MB00 barrel. Not familiar with mixing and matching though but will check out your progress tomorrow. Aside from this I dont see why they should collide although I expect the bigger rebore the more danger of this happening? http://yamahaclub.co...arch_app=forums Link to comment Share on other sites More sharing options...
Sparks Posted March 28, 2012 Author Share Posted March 28, 2012 ok its late so gotta go, have a look here for setting up the diamond shaped on...post~ #31 with 3MB00 barrel. Not familiar with mixing and matching though but will check out your progress tomorrow. Aside from this I dont see why they should collide although I expect the bigger rebore the more danger of this happening? http://yamahaclub.co...arch_app=forums Link to comment Share on other sites More sharing options...
Sparks Posted March 28, 2012 Author Share Posted March 28, 2012 Hi AIRHEAD Just to let you know , after examining cylinder and liner , some idiot has rebored liner so much off centre towards exhaust port that the piston contacted the power valve . So I will be using a different barrel for rebuild. Thanks for your input. Link to comment Share on other sites More sharing options...
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