MrMetthew

My 2 cents, I've had problems like this with nuts and bolts many times. I always cut a slot through the middle of what's left off the head of the nut with the small angle grinder on my dremel, and than start tapping it with a shizzle or flat screwdriver and a hammer. Offcourse make sure you tap at the most outer side of the slot to maximize momentum. In more extreme cases you can do the same but first grind away the head of the bolt and than grind a slot in whats left of the machined bolt. You know all the torque is stored as pressure between the head of the bolt and the surface under that. Once the head of the bolt is grinded away, normally the pressure is relieved, and the rest of the machined screw will just come out no problem at all. Edit: Don't be discouraged i've been there. But if you still have the head of the bolt I'm about 99% sure you can get the bolt out with this technique, especially the oil plug nut. Every motorcycle enthousiast has his or hers first bolt/nut that seems impossibly stuck. It will not be your last :p, you WILL get used to it :p!

@Cynic Thanks, really appreciate your opinion. Seen you around on countless DT topics. @blackhat250 Thanks for the tip, I actually did order one! Waiting for it to arrive from the USA, ordered a trailtech. Gonna start using this after all my rebuilds, carb adjustments and for heavy offroading.

I wanted to ask you guys this because there is a lot of disagreement about this online, so it seems. Whats your break-in procedure? Specifically in my case with only new piston/rings. But while we're on the subject, also with a new bore. I read a lot of contraposing things online, otherwise I would not ask. I personally always do 2 or three heat cycles warming up, cooling down the engine without riding and than start riding it easy, under 6k rpm for about 100-125miles. Is this to much on the safe side maybe? I ask because it's kinda a pain in the ass

No I actually didn't know that there was ethanol in my fuel, and although biofuels haven't really broken through where I am, a quick google did reveal ethanol in a lot of fuel where I live. Hard to find the exact %, I'm gonna ask the gasstation attendant next time I go there, I am quite interrested in this. Anyway I've put the 210 in and put the needle to the most rich position, think I'm gonna try to start her like that

Thanks for the info. Mine actually has a working powervalve servo, a 5wire one stamped with "27Feb85DC", I don't know if this is an original one can't find anything about it. Also I don't know if the carb is factory full power. I did ran the serial of the bike with the importer and they confirmed this was an original Belgian import bike. Judging from oure current rules I don't think the bike was factory full power, but geez back in '85 who knows. Any idea how I can distinguish? Anyway still trying to figure out which would be a good starting main jet, 220-230 maybe then? I don't have much experience in rejetting carbs and it seems like it's an expensive learning curve ;p. Don't want to blow her again.

Nope recesses are the same both sides. I've scoured the internet unable to find an answer. And also no the gasket itself doesn't give it away, nothing written or stamped on it. I've just ended up modelling it after the dt125r head gasket, figured they're close enough. ALSO old main jet when she blew was a 200. Is it safe to now start with a 210 as a starting point and go from there? Or how much should I increase the main jet for a safe starting point? A 210 is all that I've got right here and now.

Okay guys, parts finally arrivered. Rebuilding as we speak. Whilst I had the case apart I gave everything a good clean, polished it all up and paited it. Was not going to do this but I had the time waiting on my parts, so why not. I have an question. Anyone knows how this headgasket goes on? It also fits upside down. Its an Athena one, couldn't source a genuine one.

Thanks guys! Problem not so mysterious afterall :p. I ordered that temperature probe btw, very handy piece of kit ! Will report back after rebuild is completed

Haha, no problem bud :). Although I am really bummed UK is leaving us!

Hey guys, I am desperate trying to debug some strange problem I have with my freshly restored DT125LC (85 ypvs model with active powervalve), and wanted to ask you guys for your expertise. First some context. I bought her as a wreck at the start of this year, she was in really bad state hadn't been started in what the seller said was over ten years and standing outside in the rain for more than a year atleast (btw who does this?). So full restoration project, fully stripped her, redone frame, all new plastics, lot of new electrical connections, kilos of sanding paper, couple cans of paint, case splitted, all new bearings, rebored cilinder, new piston, carb cleanes, ... Anyway here I had a shining, almost like new, 85 dt125lc. Started really good, drove insanely nice for a 125, powerwheelie in first, unbelievable what these old machines can do. But Than a problem started to occur. Sometimes, about 5-10% of the time maybe, she like went in tho this problem mode. just from one second to the next she went bad. The throttle response was gone, the engine turned really inconsistend just like it was missing some of the ignitions, power gone couldn't even pull me, and there were loud bangs, explosions in the exhaust. When she had an episode like this where the motor was I think missing ignitions or something sometimes she would stall and when that happened you would not be able to start her most of the time until she was cooled down. But the big thing was these episodes just stopped as quickly as they came. One moment when the bike was running PERFECT and than just BAM, she entered an "episode" and started doing all these things and then after a while, just BAM again she runned PERFECTLY and you could continue your dirttrail. The episodes really were not something subtile, the bike really went from 100% to about 5% to again a full 100%. But because this happend on such unpredictable times and went away so quickly (after 15 minutes mostly) and the bike drove perfect for about 90-95% of the time I ended up riding er like this for maybe 400miles (after rebuild). But then recently while she was having a heavy one of these episodes, suddenly she stalled, no more compression, checked the sparkplug => molten metal ):. Opened her up to find a big old hole in the piston (check for pictures). WHAT I MAYBE SUSPECT: First I thought maybe bad adjusted carb, but the sparkplug color was relatively good I remember. But important to note when she was having an episode the sparkplug was sticky black. At the moment I am suspecting a bad electrical connection to the sparkplug as a lot of other connections where bad on the bike, although I cleaned a lot of the connections but maybe not all of them. I have experience with the sudden coming and going nature of problems with bad connections and this fits the bill. Missing ignitions seems to be the problem in my eyes at the moment because it would explain the bikes misfiring and unburned fuel in the exhaust to explode. However I don't find any electrical bad connection and I have all the spark wiring laying on my bench and they all look fine. WHAT I'VE DONE ALREADY °Got the engine out °splitted the crankcase, cleaned out all the metal °Ordered new piston (the bore is not damaged, thank for that) °Also ordered new sparkplug cable and new sparkplug connector ==> I am rebuilding the engine, but I don't know why the piston blew and why the bike had this strange problem (I assume they are connected??). And I would prefer to get to the bottem of this so I dont just blow the engine again :), rebuilding and running in is kind of annoying to keep doing I've put a LOT of time, effort, money and love in this bike, went to the insanely bullshit bureaucratic world of getting papers for this bike (bought it without them => last time I do this btw). And would really appreciate your guys help! THANKS IN ADVANCE !

Hi everyone, I am a, as we speak, 24 yo motorcycle enthousiast. At the moment I own two oldtimer offroad motorcycles, a 89 dt125r and a 85 dt125lc. I prefer oldtimer motorcycles of this erra and really enjoy working on them. I've fully rebuild my two motorcycles from the ground up, the dt125lc was actually a hobby restauration project, I picked it up as an old wreck as a fix-her-upper. Anyway I am here to learn and to expand my knowledge.