NEwin Posted June 7, 2011 Posted June 7, 2011 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!
DeTour Posted June 8, 2011 Posted June 8, 2011 could be a few things...Is there fuel getting into the carbureteor? I've gotten into the habbit of running clear lines, (along with an inline fuel filter) from the tank to the carb.. Maybe un screw the bolt and see if it's full and/or possibly full of debris.. You probably just need a good cleaning. How long has the bike been sitting?
NEwin Posted June 8, 2011 Author Posted June 8, 2011 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?
oscar_m Posted June 8, 2011 Posted June 8, 2011 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? Check for spark on sparkplug or replace with new, clean air filter, engage 3gear and have someone push you (of course let the clutch go at some point ). I'd think of draining the old fuel and getting the new one as well - I am not sure what happens to the oil/gasoline mixture over a long period of time, but the gas itself can loose it's parameters. regards Oscar
NEwin Posted June 9, 2011 Author Posted June 9, 2011 Check for spark on sparkplug or replace with new, clean air filter, engage 3gear and have someone push you (of course let the clutch go at some point ). I'd think of draining the old fuel and getting the new one as well - I am not sure what happens to the oil/gasoline mixture over a long period of time, but the gas itself can loose it's parameters. regards Oscar 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?
Moderator Airhead Posted June 9, 2011 Moderator Posted June 9, 2011 Check for spark on sparkplug or replace with new, clean air filter, engage 3gear and have someone push you (of course let the clutch go at some point ). I'd think of draining the old fuel and getting the new one as well - I am not sure what happens to the oil/gasoline mixture over a long period of time, but the gas itself can loose it's parameters. regards Oscar had the carb off and gave it a good clean. This chap also stated that but in fact he hadnt, I would check out the choke circuit it's basically the same carb
DeTour Posted June 10, 2011 Posted June 10, 2011 I'd consider cleaning the carb again... I know on my DT175 I cleaned the carb, i was having issues. So i cleaned it again real attentively and it fired up and sounded better then ever before. Use the straw on the carb clean and shoot it in every single hole you can find...Then blow it out with air. Also, soak the floats in a cup of gas...see if they sink or take on fuel... shake them around a little bit. Some carburetors are just a little harder to clean.
NEwin Posted June 13, 2011 Author Posted June 13, 2011 had the carb off and gave it a good clean. This chap also stated that but in fact he hadnt, I would check out the choke circuit it's basically the same carb 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.
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