speedy18 Posted January 29, 2013 Share Posted January 29, 2013 Hi guys, I've recently bought a 2002 DT 125 traily its done around 18k and is in great condition having been garaged by the last owner since 2007. it seems to have developed a issue that doesn't always happen all the time, It starts very easily and takes revs well once warmed up and pulls cleanly all the way up through the power band but. every now and then it seems to just cut out like the spark plug cap is off (instant). no warning no funny sounds or anything just a drop off in power, only used the bike 3 times off road and its done it twice, both times after about an hour or so and it wont re start until the engine is cold again, tried both a standard and iridium plug and cleaned all the wires and connections. The plan is to ride it locally on the roads around my home until it does it again so i can check the spark but i'm at a bit of a loss as to why it works when then after a good while just dies. Any suggestions would be greatly appreciated . Cheers Link to comment Share on other sites More sharing options...
Moderator Airhead Posted January 29, 2013 Moderator Share Posted January 29, 2013 does it only happen when the engine is hot then...next time whip out the sparkplug and check if it's sparking, If not it may be a coil going open circuit under high temperature, it will be easy to check with a multimeter Link to comment Share on other sites More sharing options...
speedy18 Posted January 29, 2013 Author Share Posted January 29, 2013 Thanks for the reply airhead, i'm going to try and get it out at some point this week if the fekin weather calms down a bit, It does only seem to be when its hot but on saturday it done it after an hour or so of running so put it in the van and took it to a friends rolled it out to show him ….and it started 1st kick ! 40 min drive home so it cooled right down. so cleaned all the connections and he drove it for about 10min before it did it again, he said it was going great right up to it just died , good strong power and pulled clean up to and through the power band. i'm ok with spanners but not to sure with wires, a bit like most people i guess, i bought the haynes manual so i can check the obvious stuff but how would i check this coil? I have ordered a new coil as i thought for £12 it seemed a good place to start as it looks like the original 1 so its getting on a bit and would probably be getting close to the end of its life. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted January 29, 2013 Moderator Share Posted January 29, 2013 well you have at least 3 coils to consider 1: The HT coil 2: The source coil in the magneto 3: The pulser coil in the magneto Check your manual and see what resistances are quoted for these coils and note them down along with the associated wire colours Chapter 4 Ignition system will give info on how to check these coils Link to comment Share on other sites More sharing options...
speedy18 Posted January 29, 2013 Author Share Posted January 29, 2013 RIght ,well i've ordered the HT coil for a start, can i check the resistance with a normal mega? or is it something il need special equipment for? i half wish it would just breakdown and be done with it so i could trace it and get on with enjoying the bike but intermittent faults are never that easy! Link to comment Share on other sites More sharing options...
Moderator Airhead Posted January 29, 2013 Moderator Share Posted January 29, 2013 RIght ,well i've ordered the HT coil for a start, can i check the resistance with a normal mega? or is it something il need special equipment for? i half wish it would just breakdown and be done with it so i could trace it and get on with enjoying the bike but intermittent faults are never that easy! no youre not maga testing them, mega tests are for insulation breakdown and charge 500v into the components...no need for that you will use an ordinary multimeter and take resistance readings having switched your dial to the appropriate range for the expected reading...unless your meter is a modern auto ranging jobbie, you'll have plenty of time to pinpoint the fault if the engine needs to cool at this stage we just need to know if the spark disappears when it's quit Link to comment Share on other sites More sharing options...
speedy18 Posted January 29, 2013 Author Share Posted January 29, 2013 Great i'l keep you posted when i get a chance to take it out. might need a wet suit and some flippers right now as its tipping it down and blowing up a hooly. Link to comment Share on other sites More sharing options...
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