Posts
14
Joined
2/9/2020
Location
Hartselle, AL, USA
Quick rundown on what has led up to this point ..
The bike is a 2000 yz125 I've had it for roughly 2 years and so far it has been temperamental to say the least .
So I had a wiesco 55mm piston kit laying around and out of curiosity I had my jug bored out slightly to accommodate it . My good friend is a killer machinist it took him like no time at all and no charge so hey why not 🤷 put it back together and man did it have good compression and plenty of low end for a 125 but it seemed to sputter a bit on the top end . Took it back apart and of course the power valve pins fell out which was odd because I tacked them in a few months ago to try to solve this problem once and for all. WELL the whole damn top had broken off the little slide so the pin had nothing to sit in. $162.00 later I have some nice like new slides out of a 99 yz. They looked identical in the ad and being as mine have the weird ovalish style things and not the super common round ones I was seeing these were the only ones I could find. It's all back together and now it's really flat. I can go WOT and it barely goes anywhere. It's smoking a good bit and seems to be getting really hot really fast. The plug is barely gray it basically still looks new . My coolant has held and the pump seals are brand new and no leaks out of the weep hole. I can't figure out why it seems so hot and why it barely wants to go anywhere. You can hear it kinda crossover into the pipe but there's no power 🤷 any ideas??
The bike is a 2000 yz125 I've had it for roughly 2 years and so far it has been temperamental to say the least .
So I had a wiesco 55mm piston kit laying around and out of curiosity I had my jug bored out slightly to accommodate it . My good friend is a killer machinist it took him like no time at all and no charge so hey why not 🤷 put it back together and man did it have good compression and plenty of low end for a 125 but it seemed to sputter a bit on the top end . Took it back apart and of course the power valve pins fell out which was odd because I tacked them in a few months ago to try to solve this problem once and for all. WELL the whole damn top had broken off the little slide so the pin had nothing to sit in. $162.00 later I have some nice like new slides out of a 99 yz. They looked identical in the ad and being as mine have the weird ovalish style things and not the super common round ones I was seeing these were the only ones I could find. It's all back together and now it's really flat. I can go WOT and it barely goes anywhere. It's smoking a good bit and seems to be getting really hot really fast. The plug is barely gray it basically still looks new . My coolant has held and the pump seals are brand new and no leaks out of the weep hole. I can't figure out why it seems so hot and why it barely wants to go anywhere. You can hear it kinda crossover into the pipe but there's no power 🤷 any ideas??
Also, when boring larger, the power valve has to be trimmed back to match the larger bore to prevent contact with the piston and ring.
It sounds to me like you roached the cylinder by boring it and/or the piston clearance is way too tight causing the hot running.
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