• Hi everyone,

    As you all know, Coffee (Dean) passed away a couple of years ago. I am Dean's ex-wife's husband and happen to have spent my career in tech. Over the years, I occasionally helped Dean with various tech issues.

    When he passed, I worked with his kids to gather the necessary credentials to keep this site running. Since then (and for however long they worked with Coffee), Woodschick and Dirtdame have been maintaining the site and covering the costs. Without their hard work and financial support, CafeHusky would have been lost.

    Over the past couple of weeks, I’ve been working to migrate the site to a free cloud compute instance so that Woodschick and Dirtdame no longer have to fund it. At the same time, I’ve updated the site to a current version of XenForo (the discussion software it runs on). The previous version was outdated and no longer supported.

    Unfortunately, the new software version doesn’t support importing the old site’s styles, so for now, you’ll see the XenForo default style. This may change over time.

    Coffee didn’t document the work he did on the site, so I’ve been digging through the old setup to understand how everything was running. There may still be things I’ve missed. One known issue is that email functionality is not yet working on the new site, but I hope to resolve this over time.

    Thanks for your patience and support!

Rough idle and backfire and stall under load

F

Flynn

Husqvarna
A Class
My bike seems to have developed an intermittent problem which has now become permanent.

A couple of weeks ago it had an "episode" where the engine would lose power, surge and then come back. This happened on several occasions.

The problem went away but earlier this week it came back again, then it went away again until yesterday where I had ridden into work in the morning, gone to leave and it wouldn't idle properly, I had to keep the starter tuning over to help it to idle.

I let it warm up and then it seemed to improve to the point where it would idle by itself (still erratically but enough to not stall) but then when I put it into gear and opened to throttle to pull away, it made a loud backfire from the exhaust and stalled.

To me it seems as though it is an electrical component of the ignition system that was on it's way out and has now fully "gone". The question is, which component of the system?

Me and a recovery mechanic made sure that the fuel hose was unkinked by lifting the tank, no difference, checked for a spark, strong spark coming out. I also cleaned the carb out a couple of weeks ago when I first had this issue because I thought dirt might have got into it from off road riding.

I am going to take a look over the weekend but I wanted to start this thread in case I don't find anything obvious.

I am somewhat worried if my work in this thread:
http://www.cafehusky.com/threads/stator-wire-grommet.85627/#post-609990
could have something to do with it. I thought the stator only charged the battery but according to this it also charges the condenser which is what provides the voltage for the ignition coil and ultimately the spark. Splicing the wires and their proximity to the exhaust headers could be overheating them and disrupting the current. I measured stator output and I was getting 20v, 10v and 10v so down 20v overall. Although I think it was like that before the job. But the battery is getting 13.8v at idle.

I have heat wrapped the exhaust heaters but perhaps it is not keeping the stator wires cool enough? I did run for a week with unwrapped headers without any major problems apart from a couple of episodes so maybe nothing afterall?

But we got a strong spark when I and the RAC bloke checked it?

I should also mention that last time I had an issue like this it turned out to be a chunk of flywheel magnet stuck to the trigger coil.

I am going to have a look at the weekend but any suggestions welcome.
 
Right, a morning in the garage has located the problem. For some reason, the pickup magnet had come loose, leading to it moving around and the strip on the flywheel striking it. I used plenty of red threadlock yet it has come loose.

The only thing I haven't done is tighten it to 5 NM of torque because that seems too much and I am afraid of stripping the threads out of the stator casing.

But I do set them up reasonably tightly. There are also a couple of spring washers that should be doing something but aren't.

Additionally I found some melted wiring because there isn't a heatwrap on the market which is not some crappy foil (which I have tried but looked dire).

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So where are you at with this issue Flynn? Until you showed the photos I thought it might have been something simple like a spark plug breaking down under pressure.
 
Since finding the loose pickup magnet I bought some allen key bits for a ratchet and tightened them down with threadtite and it hasn't come loose since. I couldn't find allen bits for a 1/4" drive torque wrench that I have so I just settled for tightening it with the ratchet.
 
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