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DaveyCrockett

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  1. DaveyCrockett
    New genuine ignition module fitted and it's running pretty good. Max RPM a bit slow and it has a little hesitation on acceleration, but a tune up tomorrow should see it right. Thanks to everyone who contributed to the thread, especially ADW who's diagnosis was spot on. DaveyCrockett
  2. DaveyCrockett
    I didn't measure gap before removal, but it looked sensible. I set it at 0.3 mm putting it back. A new module is on order. I will report back the outcome. You have had some pretty weird issues over the years. It seems like all the testing methods for ignition modules are not 100 %. What do people regard as the most reliable tester and is there a better way?
  3. DaveyCrockett
    I'm leaning in the same direction. Although the piston and cylinder are far from a thing of beauty, and in a formula 1 car engine, internals like this would hit the bin, this is a consumer grade chainsaw and I don't believe what I have seen would stop the saw running completely. The ignition module however ... I can imagine things inside which I can't see, that could easily cause the problem.
  4. DaveyCrockett
    Yes they are visible through the exhaust port with the cylinder assembled. Here is the inlet side of the piston. The scratch above the ring groove I did removing the ring😳. Top of exhaust port looks perfect.
  5. DaveyCrockett
    There was a little debris in the strainer, nothing horrendous. Did you mean - both flywheels and coils CAN be faulty?
  6. DaveyCrockett
    My trouble is that every part I look at, I think, well that should probably work. But ignition and engine together (forget the carb) - nothing ever looked less like a working saw 😩
  7. DaveyCrockett
    Carb was pressure tested before and after disassembly. Needle valve holding 15 psi and reseating and holding pressure when pressing purge bulb. I just have the original flywheel and ignition module. I believe they are correct matched parts. See earlier post for part numbers. Behaviour always the same, on cleaner or carb. Fires but runs down in 1/2 second, no power at all. Crankcase passes vacuum and pressure test too.
  8. DaveyCrockett
    The ring location pin seems solid. I've tried to move it with tweezers and a strong magnet. When I strip the saw everything is very wet. I think it is unburnt fuel from missed ignitions rather than running rich, but could be a carb issue. The exhaust when it fires seems on the smoky side, but the saw is so far off running properly I'm reluctant to judge it like a running saw and blame richness. The fuel mix is fairly recent - a few weeks old. It does fire on carb cleaner for 1/2 second but seems to make no power. It doesn't scream away for a couple of seconds like some things do, that gives you confidence compression and ignition is right. I believe it had fuel in the metering chamber, but brain was not thinking leanness at that point, because of wet engine internals.
  9. DaveyCrockett
    Well I can measure a couple of resistances as well as the spark test. HT to ground = 1.6 kOhm, cut out contact to ground = 60 kOhm. Doesn't prove much but HT lead good in this case.
  10. DaveyCrockett
    It was in right. I first saw both sets of scratches through the exhaust port, and I did check the arrow on the crown was pointing front.
  11. DaveyCrockett
    The only tests I can really do for the module is to jump the normal gap 0.5 mm which gives a fat blue spark and it jumps a modified plug with a 2mm gap but I know the stresses on the module are higher when it makes the spark jumps under compression. It sounds like I should take a punt on a new module. I can always send it back if it doesn't work. I have taken the taken the saw apart again to check ring wear and to provide some pictures. I've had it apart so many times now it didn't take long! The ring gap is 0.3 mm with the ring in the bore, so negligible wear. I think the scratches on the front of the piston are nothing to worry about. The blow past, wouldn't usually worry me if the saw was running. The scratches on the back of the cylinder are I think caused by burrs on the ends of the piston ring. It's not nice but I don't think it would stop the saw running.
  12. DaveyCrockett
    This is a Husq 435 II I have used the parts lists from L+S engineers website for numbers. The flywheel has the number 580 27 98 cast in the back, The parts list for series II quotes 580 27 98 01. The ignition module fitted is marked 579 63 88-02. The parts list for series II quotes 579 63 88-03. Is this okay? I think the last two digits are just a revision number. I have checked lists for 435 and 435E. They use a different parts for flywheel and ignition module. I think I have the right parts fitted.
  13. DaveyCrockett
    I was guided by the book by Paul Dempsey which quotes 90 psi as a working limit, but I think you could be right. There is no figure quoted by husqvarna.
  14. DaveyCrockett
    I have considered ignition module, but most I have seen failed are either totally caput or fail when hot. The wrong module hadn't crossed my mind.
  15. DaveyCrockett
    It still had the alu heat shield to seal it so any leak would be very minor. Most of the tuning effect from the muffler would still be there. This saw hasn't got a flat spot in the power band - It won't run at all.

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