MrMetthew

UPDATE: Ok, so we ordered parts, all included we paid a little over 600euro. That's even a bit more in "island money", for all you British folks . I don't rebuild engines without changing the main bearings so that added a little bit to the costs. Anyway the oil pump looked mint, so we're still contemplating how the crank seized. If anyone has some more input on that, that would be greatly appreciated. Honestly were thinking selling her when she's up and running again as we don't want to be bothered with another seized crank. If we can figure out why the crank seized we keep her for sure. Don't be afraid we will mention the replaced seized crank to the buyer, I don't do slimy rippoff sells, not my style. Verstuurd vanaf mijn SM-A510F met Tapatalk

Update: This '85 is turning out being a real royal pain right in the but! I finally installed the new programmable cdi after retarded delivery. And nope, no worky worky. She doesn't start, doesn't even want to start, only a loud bang in the exhaust every kick or five. I am trying to confirm if the new CDI is working correctly, but the only thing I can say at the moment is that it is producing nice strong blue sparks. Offcourse as for the actual timing of the sparks, I can't check that as easily, but I am now starting to think maybe the CDI was not the problem afteral :p... Assuming I have correct sparks, which it looks like for all of the world, having compression, than I'm starting thinking fuel again in the "fuel-compression-spark" trinity. So I'm starting to look at my carburator once again. Any advice ? Next steps I'm gonna try, try instal the old (possibly erratic) CDI again, see what that gives. Cleaning out the carb again.

Thanks for the feedback, will certainly post pics when we open the case. That wil probably be tomorrow if the flywheel puller arrived. We were thinking to Just order a whole new crank assembly, with the blueing and all. Or do you guys think this one would be a cannidate for rebuilding? Verstuurd vanaf mijn SM-A510F met Tapatalk

UPDATE: Okay, we removed the head. Valves, cylinder, piston all looked mint! BUT the crank is seized! It kinda turns partially sometimes but than seizes up when you turn a bit further. Also is blue around the part where its stuck. Big end bearings seem ok but have to split the case to check. Waiting for correct flywheel puller to do that. Do cranks just seize up on their own? Can we just replace it? Or do we need to find the reason for the crank seizing? https://s14.postimg.io/4aast20ov/20160830_213828.jpg[\IMG] Verstuurd vanaf mijn SM-A510F met Tapatalk

Update: Okay, so we started on the wr250. Got the engine out this evening. Not too bad, struggled a bit with a seized up pivot axle, but all in all got the engine out alright. Unfortunately we had to stop for the evening, not enough hours in a day. Tomorrow we'll open the engine probably, very curieus to see what we'll find in there!

Yeah, I know, we would have no goddamn leg to stand on. Luckily that dealerschip is run by a mate of ours, then again that could just make it more ugly :s. But I wouldn't dare to throw any accusations around without even fully checking the bike first. Verstuurd vanaf mijn SM-A510F met Tapatalk

Sorry couldn't control myself, came past this online and just had to order one. Just for dicking around. Less then 80GBP delivered to my door! Curious to see if it wil even run! Seems like they're a dime a dozain on ebay and the other usual china import suspects. They come in more expensive versions and rebrands also it seems, but it wouldn't surprise me if all those look-a-like engines came from the same factory. Anyway went for the cheapest one I could find, as this is not meant as a serious purchase ! I had never even heard of the concept of a "motorized bicycle", you don't see them were I live. Curieus to see if I can get this thing running on a old bike of mine, should be good fun anyhow! http://www.benl.ebay.be/itm/231848324245?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT PS: if the link expires, just ebay search "80cc motorized bike kit".

I only had time to take a quick look at it. The glass window was very hard to look through, but I was pretty sure there was oil yes. The bike was just maintenanced by a dealership, so boy that would be something if that turned out to be the problem! Anyway, this sunday or after the weekend we'll probably start opening her up. First thing I am going to do is check the amount of drained oil.

Hey everyone, My mate has a wr250f, I thinks it's a 2008 model (with the al frame). Yesterday we were riding, and at approx 50mp/h his rear wheel just blocked up! Fortunately he was able to hold the bike under control to a stop. Anyway, after that engine was stuck, kickstart kan be kicked sometimes with some effort, but we quickly stopped messing with it. He bought the bike just weeks ago second hand, so we don't have a real history on the bike. But it looks really well looked after, really mint. But also all the electronics (starter, speedo, battery,..) are removed so it also looks like somebody in the past converted it for pure offroad/racing so it may have been ridden hard in the past, who knows. The engine is still stuck when in neutral, so I expect something in the top end, maybe crank bearing went or valves, no idea. The bike was running mint before this, and was not overheating when this happened. Anyone seen these wr250 block seize up? Some insight into what it might be? The only thing I can think of now, is to open it up and see. I convinced my friend not to take it to a garage or to the "stealership" and that I would rebuild the engine together with him. I have rebuild three dt125 two stroke blocks, top ends and bottem ends. But I know nothing about four strokes, will this be a doable project? Are these wr250 four stroke blocks really that much harder to work on than say a dt125 two-stroke block? Also due to circumstances we will not be able to start on her before the end of the month. I'd better be prepared I'd figure? Do anyone knows which custom tools we need to extract the wr250 engine from the frame and to open it up? I have all the normal tools, also flywheel extracter and case splitter tool for dt125, will these fit on the wr250? I ask so we can order them in advance, before we start on the engine. So far the only thing on my to-order-list is a wr250 workshop manual. Thanks guys!

Update: Thanks for the advice. I checked them out, did a lot of research and mailed some companies. Ended up ordering a custom programmable cdi. A DC-CDI-P2 from the Company ignitech. I did however bought it from the Company Devmoto. That guy, seemed to be the only one on the market who could supply me with (hopefully) correct ignition and ypvs timing maps. Whenever I get it all up and working decently, I will post up a separate topic with a review and some info about this to help future people who have a need for a new dtlc ignition. Because its pretty hard to fînd some good information about this if your New to custom ignitions. Verstuurd vanaf mijn SM-A510F met Tapatalk Hopefully this new cdi will solve my problems with the bike. It will certainly give me a powerboost and I will have the possebility to play around and experiment with the timing and ypvs curves a bit. Which if that doesn't sounds fun to you, I don't think we can be friends [emoji14] Verstuurd vanaf mijn SM-A510F met Tapatalk

Update: Okay the transplanting the cdi didn't work out. Did not get it to run the dt125r. Possibly because first I made a wiring mistake and tried to kickstart the engine, possibly destroying the cdi altogether . Anyway will not know that for sure until I wire it back up again in the dt lc. But that seems too not matter to much as I found after rigoureus online research that my electrical problem is a known problem with the dt lc cdi (according to a very old post on some french forum). Where it momentarelly boggs down or cuts out. So new cdi it is. Now this is where it got tricky: buying a new cdi :p. I don't now why but the dt lc cdi's seem to be almost impossible to find anywhere. My eye now lays on the "sparker dc-cdi-p2". This is a sort of universal programmable cdi from a company named ignitech and they claim to support the dt125lc with ypvs. The company seems pretty trustworthy with some positive reviews online. I've emailed them to confirm the compatibility with my bike. There not cheap but at the moment they seem like my only route till an original cdi pops up online, which also are often sold for ridiculous amounts, and also this new cdi is programmable so I will be able to play with the ignition timing in the different rpm ranges which seems like a really fun extra! We'll see what the respond, and in the meantime I will keep an eye open on ebay and such.

Aah now I see it! Don't just follow the wires, follow the collors! Verstuurd vanaf mijn SM-A510F met Tapatalk

Hey guys, I'm trying to wire an DT125LC cdi into a DT125R bike. Just for testing the cdi in a different bike for debugging, ypvs and so will not be working. Anyway that's not what this topic is about. I keep seeing strange discrepancies in the wiring diagrams. I'm pretty good with electronics, but I really can't figure this one out. It's not really key that I solve this but I'm intrigued and can't really let it go now haha :p. So I thoughed I asked you guys, as we here all see the fun in this sort of technical riddles . So in the picture below. Am I stupid (that really is an option) or do I see the battery shorting out when the main switch (key switch) is turned to the "on" position?? I made it pretty clear what I mean on the picture below, just check it out. Also the wiring diagram I just got online from this link: http://www.maxperience.com/nl/yamaha-dt-125/detail/answer/107341/wiring-diagram-yamaha-dt125-r Although it looks pretty legit. Probably there is something I am not understanding !

Update: Okay the cdi switch induced more headscratching than anticipated :p. But got the cdi from dt DTLC almost wired up in the DTR. Just one more wire to figure out but for that I'll have to remove both flywheels and check out the actual wiring of the coils, I'll do that probably tomorrow evening. Pretty anxious to see if the cdi transplant will actually work. I keep seeing strange things in the wiring diagrams though, although thats probably just me ;). Think I'll maybe post a new topic about that as it is a bit unrelated.

Try to find an active facebook group about your bike and post there. That's how I find most of my second hand parts anyway.

yeah but a quick google does seem to imply that indeed the oil pump on that bike is chain driven. So he's probably is talking about that.

You're sure ther is no way to tighten the chain? Maybe take another look just to be sure. If the slack really is enough you could also remove a link form your chain. With most chains this is easily done. But I would definitely only do this as a tempory measure as your pushing the chain over its specs. A chain that did lengthen too much should be replaced anyway.

Aah great . Haha I'm gonna guess I'm not the first one to fall in that trap ! Thanks for the info! I am gonna change the cdi's then!

Update: So I checked a lot of the wiring again, removed a lot of the tape from the loom, cleaned al the contacts very thoroughly, but to no avail. First I started her up, worked perfectly, drove for about 2km no problem. Than suddenly she cut out, started running bad again, backfiring. After some minutes suddenly she ran perfectly again . This is soo anoying, it's really driving me crazy. Anyway found both the wiring diagram for my DT125LC and the wiring diagram for my DT125R. I'm gonna try to run my DT125R with the cdi from the DT125LC. See if the cdi provokes the same problems in the other bike, if so I will have found the culprit! I already figured out the wiring, so I'm pretty sure it's gonna work, unless there is some fundamental difference in the cdi's which after some research I don't think will be the case. Ofcourse the ypvs powervalve servo will not be working, but whatever. Question: I've realized the bike I have, DT125LC mk3, is marketed as a 10V bike! I've always ran it with a 12v battery though. Read somewhere that this bice is suposed to have a 12v battery (?). But do you think it's safe to try to transplant the cdi from the "10V" bike to the 12V bike? Never heard of a 10V bike tbh, although I know that the older dt's where 6V.

If your not to much concerned with your topspeed, a very simple easy and cheap trick is to change out your front sprocket with one with one or two less teeth. This if by far the most effective way to really cheaply and easily change the character of your bike. You will get more grunt out of it, but will also loose some top speed and will have to switch gears faster.

Update, the welded exhaust performed better than expected with only one small noticeable leak . I've made an alluminium bracket to mount the temperature sensor and have installed it. I've been fidelling arround with the the cdi and the wiring harnas while the engine was running and I think that induced a an episode of the bike stuttering. I've checked all the wiring and cleaned all the contacts with contact cleaner and the bike seemed to run like a charm after that (i've cleaned them before to no avail). Although It's impossible to be sure because of the episodal nature of this problem, but I'm now suspecting the wiring around the cdi again or even the cdi itself. Anyway tonight I'm gonna replace al the connectors around the cdi and the rest of the ignition system and test ride a bit. If the problem remains I probably going to end up changing all the wiring for new ones. Definitely think I'm getting closer to the problem, but it's a cat and mouse game. Especially with the episodal nature of this problem, very annoying. Anyway gonna keep scratching things from my list till the problem is solved. On a side note I've got a triple question about the exhaust system, as you can see in the third picture of my last post with four pictures of my exhaust, I've got quite a significant dent in the exhaust. 1) Do dents like this influence the performance of the bike much? Is it worth the hassle to try to fix (and possibly screw up the exhaust)? 2) How can I fix this? I was thinking one, welding some studs to the dents and somehow try to pul the dent out. Or two, cutting the exhaust open with my grinder, beating the dent out of the exhaust and than welding it back up again. 3) I've heard about gutting an exhaust, which would be the perfect time to try if I indeed did cut the exhaust open to de-dent it. Any thoughts on this? Good, bad performance wise? I've read both ways online.

Thanks, and yeah I'm pretty new to welding and hobby metal working in general. I've still got a list longer than my arm of equipment that I want to buy, but yeah I can only spend so much money on this hobby at the moment. What I actually am really wanting at the moment is a TIG welder. I actually bought this cheap stick welder off of ebay to repair a small crack in my silencer a couple of months ago. Being it was cheaper than a replacement silencer. Without any experience I took a gamble but it worked out . Now over the last past months I learned to realize a welder is like the hot glue gun of a metal worker. It's such a versatile tool, it's awesome! And certainly in the future I will eventually buy both a MIG and a TIG machine. For now I choose the stick welder because I figured it was still the most versatile and cheap of the three.

Okay, so repairing the exhaust turned out a lot more difficult than I'd hoped for. After closer inspection I figured the last owner tried to repair some leaks at the exhaust inlet with JB weld or something. Anyway the JB weld was seriously deteriorated and was leaking air. After scraping al of that JB weld off, two large holes and a big crack revealed theirselves . Also the surounding metal was seriously deteriorated and even thinner than it already originally was :p. To bad I only have a stick welder and a couple of months experience with it. But where there is a will there is a way. So after two full evenings of noobing arround I got to where I find it to be an acceptable fix for now. I used some small plates which I cut and bended to patch up the holes. Will probably have to have another pass after I figure out where my fix leaks, as it probably does, but hey remind you again, I have like no welding experience or skills and only an 100£ cheap china ebay welder. And this was a very difficult weld for me, that goddamn metal tube melts so freaking fast. And again only with my stick welder which doesn't makes it easier, luckily mine goes down to 20 amps. As far as the real problem goes I am now suspecting either the pickup coil, the cdi or the ignition modulle (this bike has). Will try to test some more to narrow down the problem. Will keep you guys updated. As you can see the damage was pretty extensive.. Again please don't judge me for my stick welding skils

Okay guys thanks for the replies. I'm back home, back in the game First things first I will tonight weld the exhaust shut. I aggree the bike is probably backfiring indeed. I doubt an airleak as I've just replaced all the gaskets, glued the crankcase together with yamabond and the problem remained unchanged. Also the reed valve is looking in real good condition to me. Coke build up in the exhaust seems possible to me as the exhaust has a reasonable big dent in it. But as this "backfiring" also sometimes occurs when I try to start the engine and everything is cold, I don't see the glowing thing fitting. "Ig fault causing the spark to occur incorrectly" Is what I'm mainly expecting. But how could I diagnose/fix this? As I understand I can not adjust the timing on my dt125lc. This happens automatically by the ignition coil. I did measure out the resistance of the the both coils in the black cylindrical box as explained in my workshop manual. But the resistances are ok. I will include a picture of the part I am talking about so you guys can be sure what I am talking about. Maybe I should just order a new one of as they are pretty cheap. Or maybe even test with the one of my dt125r. Could this be it? A faulty ignition coil? I understand there is some circuitry in this part, maybe a dried out capacitor? I can see them fail that way if there are indeed capacitors in them. What do you guys think? I'm probably just gonna order one to try. The fact that they are pretty cheap and plenty available indicates to me that they indeed fail from time to time. This is the ignition coil I was talking about. Also my temperature probe arrived today. Thanks again for the tip Blackhat.

UPDATE: !!! Rebuild fully completed. Bike starts very smooth. But the strange problem remains! Sometimes she just cuts out, missing ignitions, not all of them though just some. Also explosions of unburned fuel in the exhaust. And than suddenly she runs perfect again. Sparkplug temp sensor hasn't arrived yet, but I'm monitoring cylinder temp with infrared temp probe, hasn't gone above 75°C/167°F, also not during her running problems. What I've tried so far at the moment is try to monitor the sparking in the sparkplug. For this I wrapped an electrical wire a couple of times around the sparkplug lead/wire and connected that wire to my oscilloscope. When a spark forms, current flows through the sparkplug lead/wire, which in turn induces a voltage/current in the wrapped wire, which I could monitor on my oscilloscope quite clearly. This way I could monitor the spark timing. The idea was to see if she was missing sparks when she started to bogg down or if the problem is something else, as this would greatly help to nail down the actual problem. Offcourse Murphy, and she refused to bogg down when my test set-up was in place and she ran perfectly the whole time. I think I possibly I saw some missing sparks when she started to bogg down for a very little while, but I can't be sure and totally wasn't able to capture it on camera for you guys, as intended. I would tried more but I had to capture a plane, as I am now currently on vacation in the sunny portugal, bbqueing and sipping wine till next monday ^^. Further work on the motorcycle will have to wait till next monday, but I can order parts from here if you guys have any ideas. As a last note I did note a lack of power in my short test rides, it was like the engine had problems gitting into higher rpm, even in neutral. Offcourse this can be the not yet fully correctly adjusted carb. Also there is a rather small, but significant airleak in the pipe, right at the outlet of the engine I discovered. I'll have to weld this but I would be most surprised if that had anything to do with my still remaining problems. Ideas ?