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  • Merv
    Merv
    10 days ago
    Quoting obisteve on 13 Dec 2025 02:18 AM

    Another possibility, I think I recall you saying you changed the coils, were the ones you put in the right resistance for points? They might need replacing with electronic ignition ones now. I'd have to check to tell you the appropriate resistance coils for each ignition system.

    I think the book says 3500k ohms to 5000, and both my old coil and the new coil test at a bit over 4000 so should be ok. It's almost like it's sucking air at the head gasket when the rear cylinder gets hot, but if so then it would also blow an oily mess out on compression stroke, and the gasket edge where I can see it, plus the fins all around are bone dry with no obvious leakage. Would like to hook up a vacuum gauge to the rear cylinder inlet stub and then check what happens when it gets hot, but don't know how to get it hot without running it. I will find the problem - time is on my side. But I am beginning to think it's simply that it hates me.
  • Merv
    Merv
    10 days ago
    Well, don't know why I left it so long to address this. The gap between the rotor and electronic unit was close to .020, so I pulled the plate out and got stuck into it with the tin snips, trimming the lower LH sides so it could move in that direction, as well as a bit at about 2 o'clock so I could get a screwdriver into the gap and push it down while tightening the screws. I managed to get the gap to a firm .010, and hit the button and it roared into life! Spark looks twice the strength in my little in-line tester as well! A bit of fiddling with the idle mixture screw has it idling and responding to the snap throttle as sweet as. Talk about happy!
    Sat down until the face stopped aching from my grin, then started it again a couple times, and everything sounds good. So have quit for the day while ahead. Heavy day tomorrow with club ride in the morning and xmas party in the afternoon, so I'll plan a test ride early next week. The ignition module cost me about $70 odd, which proves that you get what you pay for. Love this old bike.

    module plate.jpg
  • Hilly
    Hilly
    10 days ago
    That's great Merv, glad the old girl doesn't hate you 😁
  • Merv
    Merv
    10 days ago
    Quoting Hilly on 13 Dec 2025 07:17 AM

    That's great Merv, glad the old girl doesn't hate you 😁

    Just added a pic of the offending bit Hilly.
    I might even have another go with the timing light and plastic plug again next week.
  • speedzter
    speedzter
    10 days ago
    I was going to comment about the poor old Mikuni taking the blame 🤣
  • obisteve
    obisteve
    10 days ago
    Bloody hell Merv, have you tried calling in a priest or witchdoctor for a home visit?
  • Merv
    Merv
    10 days ago
    Quoting speedzter on 13 Dec 2025 08:38 AM

    I was going to comment about the poor old Mikuni taking the blame 🤣

    Ha! Turns out it was me all along!
  • Merv
    Merv
    10 days ago
    Quoting obisteve on 13 Dec 2025 10:36 AM

    Bloody hell Merv, have you tried calling in a priest or witchdoctor for a home visit?

    Haha! Appears the old girl doesn't hate me after all Steve. She was just trying to further my education!
  • obisteve
    obisteve
    8 days ago
    Must have missed your post about adjusting the rotor/sensor gap, stuff generally works better when it's within spec.
    I was starting to think that you were being haunted by ghosts of electricity, sometimes there and howling, sometimes completely absent.
  • Merv
    Merv
    8 days ago
    Quoting obisteve on 15 Dec 2025 02:11 AM

    Must have missed your post about adjusting the rotor/sensor gap, stuff generally works better when it's within spec.

    I was starting to think that you were being haunted by ghosts of electricity, sometimes there and howling, sometimes completely absent.

    May still be mate. May still be.
    There were no specs with the unit I bought, unfortunately. So, I was so happy yesterday, when after that adjustment it fired right up, ran great, turn off and wait ten minutes, then fired up again first hit. Went to bed happy, and big grin when I went out to it this morning, turned the fuel and ignition on, hit the starter and not a single kick. Did not, and will not, fire even once. 34c today and near 40 in my shed, so another day in front of the telly in the air-conditioning. So disappointed. Think I will buy a single fire coil, as well as a better quality electronic unit. But will kick the tyres again for a few days first.

  • Merv
    Merv
    8 days ago
    First, I might check the voltage at the coil while the motor is turning, just in case the starter motor is a bit hungry.
  • Hilly
    Hilly
    8 days ago
    Merv if you haven't already I would google the bejesus out of that spark unit you got, if you are having issues with it you won't be the first and you just might find a link to an obscure forum somewhere that gives you the key bit of wisdom you need, other thought is if it is a copy of a well known unit then find out what specs that has and sneak up on yours with that, I thought you had it, I really did! And I thought mine was a bit of a gremlin lol.
  • Merv
    Merv
    8 days ago
    Quoting Hilly on 15 Dec 2025 04:12 AM

    Merv if you haven't already I would google the bejesus out of that spark unit you got, if you are having issues with it you won't be the first and you just might find a link to an obscure forum somewhere that gives you the key bit of wisdom you need, other thought is if it is a copy of a well known unit then find out what specs that has and sneak up on yours with that, I thought you had it, I really did! And I thought mine was a bit of a gremlin lol.

    Nah. It was a cheap unit Hilly, that I bought even before I fitted the new points. Bought it while it was there with the thought I might use it one day.Wish I hadn't, cause sometimes it works, other times it doesn't. I think I might bin it and get a name brand replacement. Just the time it takes to get it prolongs the agony a bit. But one day! One day I'll be able to ride this old girl. And by then, she won't be game to break down cos I'll know everything about her.
  • Merv
    Merv
    7 days ago
    Turned the key again late yesterday and she fired up again strong, so I now know what the problem is. Won't start it again until I have a muffler fitted so wishing you guys all a great, happy and safe Xmas, thanks for your help, and see you all in the new year.
  • obisteve
    obisteve
    6 days ago
    I'm glad of that Merv  but what did you do between posts that let you identify the problem???
    Quick, the suspense is keeping me awake.
  • Merv
    Merv
    6 days ago
    Quoting obisteve on 17 Dec 2025 10:46 AM

    I'm glad of that Merv  but what did you do between posts that let you identify the problem???

    Quick, the suspense is keeping me awake.

    Didn't flood it is all Steve. So still needs fiddling with but certain now carby tweaking and replace el cheapo spark unit will have it on the road. Started on exhaust plumbing today, and with the daughter up from Canberra in a week, I'll get plenty of shed time over Xmas while she takes her mother shopping.So won't be long. Thanks heaps for your help mate, and the others who have commented. Ride safe over Xmas.

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