t20racerman Posted December 28, 2016 Report Share Posted December 28, 2016 Hi all I've been restoring my TR77 for 18 months after it sat in bits for 16 years. On completion it had a huge fat blue spark and started brilliantly many many times whilst I was finishing it off. Got it road registered and went for a test ride. After 12 miles of the engine running smooth as... it suddenly stopped. Problem, no spark at all. So, is there a guide anywhere of what to check, what values to expect etc? I My Clymer manual tells me that it is an electronic ignition model, but the new points and condensor I fitted suggests otherwise! I have a good meter, and understand the ignition system, but have no data or values to check against. Yes I have checked the plug! Any ideas or suggestions welcomed. Quote Link to comment Share on other sites More sharing options...
spen Posted December 28, 2016 Report Share Posted December 28, 2016 Have the points closed up? Has the new condenser failed? Quote Link to comment Share on other sites More sharing options...
spen Posted December 28, 2016 Report Share Posted December 28, 2016 http://www.trialscentral.com/forums/topic/48672-ossa-mar/ Quote Link to comment Share on other sites More sharing options...
woody Posted December 28, 2016 Report Share Posted December 28, 2016 The Clymer and most other manuals were written before the TR77 was in production. All earlier Ossas used electronic which is why they don't mention points. Can't help with the problem as electronics are a mystery to me but check that the wires aren't broken where they exit the crankcase and bend 90 degrees, if they still exit at the original point. This used to be fairly common issue, especially if they've gone brittle through age 1 Quote Link to comment Share on other sites More sharing options...
dadof2 Posted December 29, 2016 Report Share Posted December 29, 2016 Try starting it without the condenser. Condenser resistance should be at least 4 Mohm (M = Mega) HT coil primary to ground should be 1 or 2 ohms. HT secondary to ground should probably be about 3,000 ohm. Source coil should be fairly low resistance, probably less than 8 ohm. Spin flywheel with a power drill, coil should give 18 vots AC or more. 23 plus common. Check points conduct - I have known corrosion between rivets and points parts to become none conducting HT lead continuity. If resistor type lead about 2,500 ohms per 100 mm. If non resistive type only a few ohms. 3 Quote Link to comment Share on other sites More sharing options...
t20racerman Posted December 29, 2016 Author Report Share Posted December 29, 2016 Hi all - thanks for all of the replies - especially so to dadof2 as that was just the information I was after and I was reluctant to strip the relevant bits in my freezing cold garage without knowing some values. :-) Anyway, to cut a long story short, it was an easy problem to see in the end - the end of my (new) points had snapped off! new ones ordered.... but worried that the same might happen... Quote Link to comment Share on other sites More sharing options...
dadof2 Posted December 29, 2016 Report Share Posted December 29, 2016 Glad you found it quick. I now always test new (or suspect) points for conductivity before fitting. Checking them with a meter typically puts about 9V across them but very low current flow. To test them properly it is far better to use a 12 volt car battery and a headlight bulb. Check the voltage drop or compare the bulb brightness with and without the points in the circuit. It is surprising how many points fail this test yet show zero or very little resistance with an ohm meter check. Same principle applies to relays - they need to be tested using a decent load to ensure they actually conduct properly. 1 Quote Link to comment Share on other sites More sharing options...
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