82desmo Posted August 5, 2018 Report Share Posted August 5, 2018 (edited) Hi all, I have just acquired a 1976 TL250 that is in need of a good tidy up. (I am yet to start it) Today I looked at the electrics and discover a complete mess. One wire had 4 joins in 200 mm and there was a lot of patching and redundant wiring that bit by bit I removed and the bike now has no lights at all - just a on / off switch on the handlebars. Following the old wiring the coil, kill switch and points were all joined together and ran to the stator. Seems too simple??? What I am left with is a VERY basic set up and I just want someone who knows the TL250 to confirm: 1. Where does the yellow wire coming out of the stator go to? 2. The coil, kill and points all join at the same point - does this matter? 3. Does my diagram look correct - will the bike run and stop when required. Thanks in advance! Edited August 5, 2018 by 82desmo Better drawing uploaded Quote Link to comment Share on other sites More sharing options...
maxwell smart Posted August 5, 2018 Report Share Posted August 5, 2018 (edited) Hello Desmo. I believe u have it drawn right. the stator has two complete separate coils. one for the ignition system and one for the optional light system. the black/white lead is for the ignition and the yellow is for the lights 6 volt lighting. u will not use the yellow at all if no lights. the points connect to the ignition to supply a ground point that switches on and off to create each spark at the spark plug. remember they have to be clean enough to actually connect to ground or u will not make any spark. the kill switch grounds the system permanently when switched off to kill the spark. how does it work. when the points are open during the phase of rotation there open, the mag coil is energizing the primary side of the ignition coil, when the points close the voltage is stopped from flowing and the built up electrical field in the primary side of the ignition coil goes out thru the secondary side of the coil stepped up to a very high voltage thru winding ratio and travels to the spark plug and sparks to ground there. then the points open back up and the voltage flows again to the ignition coil building the voltage field and when the points close again it sparks again. remember its essential to use non resister spark plugs and non resister plug cap or the engine will never run right when u get it started, ive seen too many times people using 5k resister modern plugs or 5k plug cap and not understand why it wont run right, modern resister plugs and caps are only for electronic ignition system use and reduce the spark intensity on a points application causing poor running. check Wikipedia for the theory of points ignition systems for a clearer write up and understanding of the system, ill try to post up a wiring diagram later today. one more thing, the tl250 I purchased had a newly rebuilt engine but would not start in spite of having the three items for ignition , it would spark had compression and had fuel. but the cam that opens the points was assembled out of phase 180 degrees so the spark was happening on the wrong stroke . exhaust stroke not the compression stroke , took me a while before I figured it out. hope this helps. gotta go surfs up. Edited August 5, 2018 by maxwell smart correction Quote Link to comment Share on other sites More sharing options...
82desmo Posted August 5, 2018 Author Report Share Posted August 5, 2018 Thank you so much Maxwell. Great detail and easy to understand. just a quick one...how do I check if my plug and cap are 5k. If it was on the bike, would you expect then to be ok. So Ai just worry about it if it does not run right? thanks again. Mal (82desmo) Quote Link to comment Share on other sites More sharing options...
maxwell smart Posted August 5, 2018 Report Share Posted August 5, 2018 (edited) hey, the spark plug cap will actually have 5k printed on it if u look close. and the spark plug has to be the original spec as shown on the parts list not the iridium equivalent modern plug. people often think the iridium upgrade is smart, but in reality it wont work on points ignition. I looked at ngk replacement spark plug caps on ebay to see the difference between standard and resister type so I could start spotting improper setup from a distance now. u could probably look at the ngk catalog to see the difference as well. I recently purchased a ct70 honda with a resister cap on it by mistake and it ran much better after a new standard cap was installed. Edited August 5, 2018 by maxwell smart added info Quote Link to comment Share on other sites More sharing options...
82desmo Posted August 5, 2018 Author Report Share Posted August 5, 2018 Thanks Maxwell. Quote Link to comment Share on other sites More sharing options...
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