kenomi13 Posted March 30, 2011 Posted March 30, 2011 Hi, Brief intro... I'm on my 3rd Yamaha now since i started riding a neos scooter at 16, i thrashed the hell out of it and it was faster than my mates and never blew up yet their 50's contantly did so this made me a yamaha loyal. 2nd was a YBR 125, good on fuel but boring as hell, that got stolen and i didn't even have cover for theft, so that was more than annoying. i'm now i'm on a DT 125 LC mk 2 that i bought the other day stripped down wire brushed and sanded all the crappy old flakey paint and rust off, repainted, fresh bolted and restored the plastics. It had apparently had an engine rebuild 35miles ago so i didn't bother touching the engine, 26miles into it and the thing seizes. Plenty of 2 stroke, i even put 2 stroke mix in the freshly cleaned out tank until i was sure the oil pump was working. I made sure it had plenty of gearbox oil and coolant in it. i thought nothing could go wrong, until the piston somehow manages to hit the cylinder head and knock a big crater into the piston and smash my sparkplug to bits!! how is this even possible? i've taken the head and barrel off and the crank is fine with no play, the bearings are fine, feels like it's lubricated enough and there does not appear to be any way of the piston reaching the head. I'm confused, only thing i can think of is if something exploded in the cylinder and made the crater and destroyed the spark plug, could this happen with a double dose of 2 stroke mix? or perhaps abit of the de-greaser i used to clean the bike found it's way in somehow and exploded What's your thoughts on this? i'll post some pics up when i've taken some as i have no doubt you will like to see the state of my blown up piston. sorry if this is a long introduction. Lee
kenomi13 Posted March 31, 2011 Author Posted March 31, 2011 update, i think it was an explosion cause by too much air in the mixture or slight water in the cylinder either both caused by a shoddy head gasket. another thing i would like to know for when i've rebuilt the top end is what mods other dt 125 lc owners have done to make it more versatile powerband wise with the power valve, i know about servos, just have no idea what kind to look out for as its an Lc model with the PV and exhaust on the other side and i can only find info on the dtr model. i might just fit a lever to choose quickly the position of the PV. has anyone got any helpful knowledge on this topic? cheers, Lee
Moderator Airhead Posted March 31, 2011 Moderator Posted March 31, 2011 Hi Lee and Start a topic in the workshop or somewhere more suitable than 'Noobs' which is really just an intro forum. Just copy / paste what you said here
kenomi13 Posted April 2, 2011 Author Posted April 2, 2011 cheers, i've pretty much figured it all out. i have a MK2 which is supposed to have the non ypvs engine, but along the line sometime someone has replaced the top end with a MK3 powervalve barrel which does not line up the water channels to the bottom, thus it overheated and blew the head off. i've just bought 2 of the right engines off ebay so should have a lot of fun making one standard one and one tuned up one. can't take any pics yet as it is in my bedroom in pieces at the moment and i would rather unveil it when it is all shiny clean and working.
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