NEwin

ok, this sounds exactly right. I'll get to work this week. Where's the best place online to find out about carb settings? My Hayne's Manual is a little vague.

All has been done. Even though the spark seemed fine, I still replaced the ignition coil, HT lead and plug out of frustration. I also replaced the air filter. And replaced the fuel. After all this we tried pushing it along in third gear. Nothing substantial happened. It sort of felt like the engine was firing very very weakly whilst it was being pushed, but it stopped the instant someone wasn't pushing it. This thing is really driving me crazy. The spark seems good, the compression is good (used a compression tester and got around 100 bar, which I'm told is correct) and the carb has been cleaned thoroughly. For some reason I'm still thinking the problem is the carb but i'm far from being an experienced mechanic. Is there any way I can test the air/fuel mix getting into the cylinder directly?

It's been sat about a year. I've already had the carb off, and given it a good clean, and that didn't help. Fuel is definitely getting to the carb, but I'm just wondering if the lack of condensation on the spark plug means that the carb isn't putting enough fuel in the incoming air?

hey guys, I've got a dt125lc mark 3 that's just not starting. I kick it over, and nothing happens at all - no misfire or ignition of any kind. I'm currently working on the theory that the issue is with the fuel not getting to the cylinder. Whenever I've kicked the engine over a few times, and then checked the spark plug after, the spark plug looks perfectly dry (there's a little moisture on the bottom end of the thread, but that looks like grease/oil) - is this normal? I would think that if enough fuel is getting to the chamber, and no ignition is taking place, then some of the petrol would condense onto the spark plug due to the compression - is that right? cheers!

hey folks, so i finally got around to getting a compression tester (i moved house recently so things have been .... hectic), and the results are ..... 100 psi. Is that good/bad/other? cheers.

ok, so we tried the bump start (in 2nd gear actually, in case that matters) and the engine did sort-of start but with almost no power, and it sounded .... pretty weak i guess. Even with the throttle at max, it didn't have enough power to pull away and as soon as we stopped pushing it, the engine died. Any ideas what this means? We're gonna get hold of a compression tester, i think, so I should be able to give more info soon....

cheers guys - I just got back from a couple of weeks in croatia so will be trying all this, this weekend. Will let you know how our (3 man) bump start goes....

ok, will try to bump start, although the nearest hill isn't really that near (especially considering I'll have to push the bike over there) so it'll probably have to wait until early next week. Is it enough to push it along the ground (will this get enough speed up)? Actually, come to think of it, how exactly do you bump start something? Do I just kick it over whilst it's in motion, or do I have to do something with the clutch? with regards to the compression, if the compression is bad, is it just a case of replacing a few gaskets, or is it gonna be something more involved? I'm just trying to determine whether it's worth buying a compression tester, or whether it's just worth assuming the compression is bad, and then doing whatever work is needed. cheers.

hey choc teapot, I can't say I know too much about things myself, but I've found to be pretty good when it comes to spares and replacements. They also have a variety of different 2 stroke oils listed. hope this helps a little!

I haven't tried a bump start - will this work even though the engine isn't igniting at all? I'll check to see if the plug is getting wet. As for the compression, I did what KirriePete suggested. I took the plug out, put my hand over the hole and kicked it a few times. I then added some oil, and did the same. As far as I could tell, nothing changed. Is there any other way of checking the compression?

nope - not a thing. no banging, no spluttering, no half-hearted running. there's not even a hint of some sort of ignition.

ok, so I checked the compression - as far as I could tell, it was the same before and after i added the oil. then I swapped out the old petrol for new, and the thing still won't run. Is it now just a case of giving the carb another clean?

yeah, I checked late last night, and the spark seemed stong and decent enough (although I don't really have a basis of comparison). any ideas?

hey, yeah, we used a multimeter lead with croc clips to make sure it was grounded, and that's when we first noticed the cracking noise, although definitely can't see much (although it was an insanely bright day so maybe that was a factor). yeah, i've got a haynes manual.

ok, as awesomely funny as this has become, does anyone have any advice that doesn't involve me getting zapped?

errrr.... hey, jebb - i might give that idea a miss if that's ok with you. I realise the current is low, but I still don't like the idea of 40,000V running through my body. Of course, if you wanna come lend a hand.

hey guys, I've been trying to diagnose why my DT125 LC Mk3 has suddenly stopped working after it was left for a few months over the winter. The engine doesn't start at all and therefore, as far as a beginner like me understands, it's either a problem with the spark, or with the mix coming into the engine. So, I tried to see if the plug sparked whilst outside of the engine, and as far as I could tell it didn't. After playing around with the multimeter, I decided to replace the ignition coils, and the spark plug. Seemingly, still no spark. At the same time, I'd been advised that maybe the jets in the carb had become blocked, so leaving the electrics for a while, I checked the jets, and sure enough, the pilot jet seemed blocked, so I cleaned it. Still no joy with the engine. Going back to the electrics, I rechecked the spark plug, this time using a wire to make sure the plug was properly grounded (I'd been worried that this wasn't the case before). This time, there was a definite electrical cracking sound (it is possible that this was there all along, and that I just hadn't noticed it) when kick-starting, although the spark still wasn't visible. In any case, the engine still wasn't firing. So, that's the state of play, and as I'm pretty new to this, I don't really know what to do next. I'd be massively grateful for any advice. Oh, and here are some random thoughts/questions that I've got: - Could it be a weak spark? If the spark was right, would I be able to see it outside the engine as well as hear it? Is there any easy way (i.e. without specialised equipment) to check the strength of the spark? - I'm assuming that if the timing was off, then the engine would at least mis-fire or something? - Could I have messed something up with the carb whilst cleaning it? I'm pretty sure everything went back exactly as, but if the carb is really sensitive to changes (as some people have suggested), is it possible I've made things worse? - Does the initial spark for a DT125 LC Mk3 come from the flywheel, or straight from the battery? (or maybe a combination of both?) - Could the CDI unit have become damaged over winter? Could this cause a weak spark? Sorry for the long post. Cheers!!!

hey guys, As part of a long stretch of problem solving I'm gonna remove, dismantle and clean the carb. I've got a haynes manual, but this is the first time I've ever done this so I was wondering if anyone had any particular advice? cheers!

hey guys, Was just wondering if anyone knew how to check if a CDI unit for a DT125 LC MK3 was working. My Haynes manual just says that Yamaha doesn't publish the spec. cheers!

hey, So my bike decided to stop working over winter and am currently running through various possibilities. As past of this I discovered that the bike is wired differently to the wiring diagram in my Haynes manual. Basically the engine kill switch doesn't appear to be wired to the CDI unit as the haynes wiring diagram suggests it should. However, the bike was running fine before so I tempted to put this down to an error in the haynes manual, but I was just wondering if anyone had an alternative wiring diagram (or was sufficiently in the know)? cheers.

so tried the spark plug, and didn't see a spark whilst kick-'starting'. Replaced the plug and still didn't see a spark. I'm assuming that you don't have to worry about the gap size for a new plug? (I don't have anything that's capable of measuring a small gap accurately anyway ) it is possible/likely that the ignition coil is damaged? also, ran the carb through with petrol and that didn't fix anything so maybe i need to play around with the jets.

hey guys - cheers for the advice - very useful! I'll try all this over the weekend, and see how it goes. cheers!

so i suppose a good start would be to ask, what sort of things should i be looking for, in order to help me diagnose the problems. cheeers.

hey, I left the bike outside over winter (covered as much as possible, but i don't have any inside storage space). When I tried starting it up again a few weeks back, the engine wouldn't start. I don't really know too much about the mechanical side of things, and I figured this would be a good excuse to start. Any ideas? I thought I'd start by changing the spark plug - i've no real reason for thinking this will solve the problem, but again, it seems like a relatively basic task that I should probably learn, even if it doesn't solve my immediate problem. cheers!

hey, This is my first winter with a bike, and I wasn't sure if they needed any special care during the colder months. Basically, I'm gonna be away for about a month, so I was just wandering if there is anything I should do to prevent the bike from becoming damaged due to the cold, especially since it won't be used for a while. I don't have anywhere to store it inside so my options might be limited. cheers!