xt125r

hi all , i have an xt125r baught new in 2009 , on three quaters to full throtle this bike has had detonation from new , i have only done 1400 miles on it but was wondering what damage this could have done ! at first i thaught it was the carateristics of the engine , then i thaught it was the restrictive exhaust and air clean up system on the exhaust . i had fitted at the dealers a new arrow exhaust system and when the problem was still the same i new it was pinking due to a lean mixture at over half to full throtle , it is at the dealers now and suspect that a larger main jet is going to be fitted to repair this problem , its stupid how engines have to be leaned off so much with older designed engines that are not made to run like this . i will let you know how i get on . ps. anyone else had this problem on any other carborettor yamaha bike !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!