steptoe1111 Posted August 30, 2014 Share Posted August 30, 2014 Hey guys got a problem with my "77"dt175e I've got a very poor spark , it started happening the other week ....what I initially thought may have been some bad gas or the main jet had maybe sucked up a little blockage ... I cleaned the the carb out thougherly like I've done many times but didn't help ... Then I started looking at the electrics and found I've got a very week spark , I've had the plug out many times and it only needs a little turn by hand on the kick starter to get a nice bright strong spark ....only now you really have to spin that motor up fast to get a little one, The bike is running if you can roll start it fast enough hard to keep it idleing and the motor dies above 2500rpm At the time it started playing up I was doing a few jumps at home in the paddock nothing extreme only a couple of feet I thought maybe I had cracked a ring or done something to the crank ....I wasn't putting her under a lot of stress I never do cause she's fourth years old But I still have enough compresion well 85psi + So I pulled the flywheel and I had noticed that the smaller of the two coils on the stator plate (on the right hand side of the pick below the two coils large one with the smaller one bolted on top of it). Had twisted now whether or not that's from hitting the inside of the magneto I'm not sure ....but I think most likely from heat maybe? Now I had been running the bike without a headlight no battery and no regulator only the tail light was hooked up ....due to the wireing system being a mess. ..... I only just discovers is meant to be a big no no From closer inspection my lightning coil that supply power to the battery and headlight was black and looked fairly cooked. But I'm that still works. But on the dt175e they don't require that one to run the ignition system releys on the other two coils I have included a pick of the stator for I'd. "Its not a points/condenser type" Does any one know what the ohms readings should be on those two coils there is also a small square one about the size of your finger tip at the top of the stator in the middle between the lighting and two source coils I'm not sure what that is and the reading for the ignition coil ? I was under the assumption that with ignition coils and cdi units they either work or they don't so I'm geusing that one of those source coils is failing under load maybe? If any one could help with those readings I'll get the multimeter onto em soon as and post the readings Or if anyone has had similar problems and could possibly shed a bit of light on what my problem with the old girl could be I'd be greatly appreciative thank you http://i647.photobucket.com/albums/uu196/steptoe1111/PICT0754_zps9ef832c6.jpg Link to comment Share on other sites More sharing options...
Moderator Airhead Posted August 30, 2014 Moderator Share Posted August 30, 2014 Hi shaun have a read of this fella DT175MX Ignition checks There were two versions of ignition systems on DT175MX bikes. The mk1 version from the earlier bike had a 7 wire CDI the early bikes had a round section swing arm. The mk2 version had a 6 wire CDI, the red wire is absent on these. These bikes have a square section swing arm. The HT cap (AKA spark plug cap) unscrew it off the HT lead, it is supposed to be a resistor cap so should be around 5K Ohms The ignition coil primary...Orange wire to battery neg should be 1 Ohm +- 10% The ignition coil secondary...HT lead to battery neg should be 5900 Ohms +- 20% If the readings are much higher, check the ignition coil has a clean ground connection. Yes and the ignition coil mounting is a wiring harness ground point too, so check its clean and bright there. Disconnect all the wires from the CDI. Then using your multimeter on the loom side of the connectors.Black probe on a clean part of HT coil ground point Red probe on...... Orange, Meter to 200 Ohms, expect 1 Ohm (HT coil primary) Brown, Meter to 2k Ohms, expect 420 Ohms for mk1 and 300 Ohms for mk2 (Magneto charge coil) White/Red, Meter to 200 Ohms, expect 12.4 Ohms for mk1 and 10 Ohms for mk2 (Magneto pulser coil) Red, Meter to 200 Ohms, expect 13.6 Ohms for mk1 only. (Source coil 2 or high speed coil) Black female connector, Meter to 200 Ohms, expect dead short repeat for black male connector Any difference in the results for the two black wires may possibly be rectified by cleaning the front engine mounting bolt and a little of the frame behind the bolt head, then tighten to torque spec. Black/White, Meter to 20K Ohms, with ignition off expect dead short, with key on expect open circuit, with kill operated expect dead short (Engine kill operation) If all these tests are good you would be well advised to try another CDI. If they are not good...reading higher...disconnect and clean any plugs/sockets you find along the way, if the magneto coils are reading lower, new ones needed if more than 10%...or so the book says Finally, if you are working with a box full of mixed parts! Mk1 1 flywheel is Mitsubishi F3T250, it has two slots in the face of the flywheel Mk2 flywheel is Mitsubishi F3T251, it has four slots in the face of the flywheel Link to comment Share on other sites More sharing options...
steptoe1111 Posted August 30, 2014 Author Share Posted August 30, 2014 Thanks a lot airhead I'll try to do those checks tomorrow mate and post what I find cheers mate Link to comment Share on other sites More sharing options...
steptoe1111 Posted September 19, 2014 Author Share Posted September 19, 2014 ok well a few days late but i got a few spare hours to fool around in the shed today it seems i have a 7 wire cdi with the round swing arm so i have a mk1 i did some pokeing around with the digital multimeter and: Disconnected all the wires from the CDI. Then using my multimeter on the loom side of the connectors. ignition coil primary 1 ohm ignition coil secondry 5.95k ohm Black probe on a clean part of HT coil ground point Red probe on...... orange 1ohm brown .385k ohm for the charge coil ?? "unsure about this one" white/red 11.4 ohms red 8.9 ohms Source coil 2 or high speed coil should be 13.6ohms im only reading 8.9 does this sound likely to be the culprit ? apart from that do my other readings seem ok ? Link to comment Share on other sites More sharing options...
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