johnboy999 Posted May 1, 2016 Report Share Posted May 1, 2016 Hi all , Can someone please tell me how soon before TDC the points should open and the gap to set them, Weak spark and I am unable to see them opening at all, Thanks. Quote Link to comment Share on other sites More sharing options...
spen Posted May 1, 2016 Report Share Posted May 1, 2016 If my memory serves me well, I seem to think 0.3 to 0.4 mm points gap at 3mm BTDC. Quote Link to comment Share on other sites More sharing options...
spen Posted May 1, 2016 Report Share Posted May 1, 2016 Googled it...... Yamaha specs for this bike are : timing is 3.1 mm BTDC point gap .012" to .016" Quote Link to comment Share on other sites More sharing options...
johnboy999 Posted May 1, 2016 Author Report Share Posted May 1, 2016 Thanks Spen , I take it that the points start to open 3.1mm before TDC, I cannot understand why I now have a weak spark as I did not touch the points when stripping the only other thing maybe that where the HT coil fastens to the frame it not making a good earth due to the powder coating ,....?????? What you think Kind Sir. Quote Link to comment Share on other sites More sharing options...
spen Posted May 1, 2016 Report Share Posted May 1, 2016 As per 'phone call, grind that powder coating off..... Quote Link to comment Share on other sites More sharing options...
pacificnw1 Posted May 9, 2016 Report Share Posted May 9, 2016 I have a 74 and have good spark after some chasing. I am no expert but here's my $.02 worth... If the coil has bare brass mounting surfaces - like the guys said already - clean the bike's mating/adjacent surface and add some light oil against rust - see "faying surfaces" for a boat load of rubbish on this that says A Good Ground is important. Manuals are on line - cheap and comes via email and a then a cd a few days later. It knows stuff. Ask the guys with the Spanish made bike what they wouldn't give for a decent manual! Remove the ignition back plate and unplug the cable. On the bench - Clean the bell housing inside diameter with 400-600 - cleaning only! Blow or wash sanding dust away. A light coat - thin film - a spray of WD40 is okay. Spray it on and wipe it clean. Remove and replace the condenser (or chase it for the next six months - up to you) Clean or replace points (if needed change the points adjusting/mounting Screw too). The points are set @ <.015" and burnished with a match book or business card - 'til it comes out clean. Check harness at the gromet where it exits the engine case. Stiff wire here is a failure wating for some vibration. It could work part time/intermittent - as mine did or may create a high resistance path and weaken coil response - not sure but I do know stiff wire that should be flexable is bad. Good luck - no school like old school! For good reason - of course. 1 Quote Link to comment Share on other sites More sharing options...
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