kenomi13

Hi, i have a DT 125 lc MK 2 or 3 (can't figure out which) with a YPVS engine and powervalve that is not functioning as it doesn't have the servo motor. i've been searching for ages for info on this for this bike and all i get is bombarded with info about the DTR which has a completely different engine and the power valve on the opposite side. i have searched ebay for a couple of weeks for one for a DT 125 lc and for RD 125 lc as i believe these have the same engine but cannot find one at all. are there any other ones that will work? like maybe off a bigger bike. its the 34x engine and it has the powervalve on the right hand side with 2 bolts to mount it to completely level on each side of the valve. cheers, Lee

i want to search for posts about my bike, a DT 125 LC mk2 but i do not know how to search for this as it only lets you search for words and "DT 125 LC MK2" contains no words. how can i filter results to just show ones relevant to my bike? cheers

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.

i've got a spare lc MK 3 barrel and cylinder head for sale, it's the round type with the powervalve, just needs a rebore as it has light marks. the powervalve alone sells at quite abit on ebay so make me an offer for the lot, or even just the bits you want also i'm going to have 2 spare complete bottom ends, from the crank to the front sprocket for a MK1 and 2 Lc 125 so if anyone wants any bits off these make me an offer, hopefully this helps someone in my situation without them having to buy 2 whole engines just to get one part from it. cheers, Lee edit...sorry i am new to this forum and believe i may have posted this in the wrong section, didnt see there was a for sale section. i'll post it in there.

Hi, my DT 125 lc MK2 blew up yesterday, so naturally i took the barrel off to noticed that the top of the piston had melted, not too much of a problem as it's an easy repair. but i've noticed that the bottom end of the engine is a MK2 engine (the square one without ypvs) and the barrel is a MK3 (Round with a powervalve) and that they aren't designed to go together as the water cooling channels are on the opposite side of the engine, someone has bodged the 2 parts together using silicon rubber and blocking up the water channels!! what should i do? i have found a set of engines on ebay ebay link i could put it back to how it's supposed to be without a powervalve, but quite pricey. how are the pre-ypvs engines? do they have as much power at the top end rpm as the ypvs ones and suffer at the bottom or have they made them so they are better at the bottom end of the revs? i liked how i could alter the powervalve to how i wanted it to respond, fully open for going fast on the road, and closed for towns and off-roading. if anyone has a spare barrel and head for a MK1 or 2 LC i would rather just buy that than 2 complete engines so let me know, im going to new york on saturday though so may not be able to respond, depending on the internet situation there. thank you to anyone that can help Lee

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

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