• Husqvarna Motorcycles Made In Sweden - About 1988 and older

  • 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 The previous version was outdated and no longer supported.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!

What is a ping ?

From what you have read now doing some research. Just remember, pre ignition causes detonation / pinging. Detonation doesn't cause pre ignition. But this phenomenon would likely occur when the engine is under a load at wider throttle openings.

Do as "Tinken" says above a thicker base gasket alone could cost very little and if the engine is detonating it would be a negligible expense compared to putting a hole in the piston. If it is in fact detonating its about the same as beating the piston with a hammer.
 
Never heard of a 250 pinging, mostly big Bore Yamaha's ping, & like mentioned under load only.

How did the 93 octane work, higher octane runs cooler? Still sounds like a jetting
 
When I start reading of the left over gasses after the spark and flame front did their thing going off and then different definitions, well I really don't grasp that too well. I would make sure where that stuff is coming from, the text, and see if it is from a similar engine to what you have in mind. Two cycle diesel or four cycle gasoline etc.
 
Not saying your bike is actually pinging., I certainly don't know.

The flame front/probagation travel in many 2 stroke combustion chambers is such that it is not directed out towards the edges of the piston and its rings. This can be due to the design of the squish band itself just inward of the head gasket sealing area and how much clearance their is at top dead center on the piston. The rest of the dome above that in the heads combustion area many times has a sharp angle like a bowl therefore the flame probagation speed from where it takes place at the spark plug can be directed down at the pistons dome. Not out to the pistons edges, due to the domes configuration in the squish band area. This can be due to the percent rise of the domes on many replacement pistons it self. Or what the pistons crown shape really is.

Relieving the squish band angle,. Making it wider and increasing that angle in relation to the angle of the piston's crown at top dead center and widening it at the same time can be done. Even after cutting or shaving the head gaskets mating surface to increase compression on the head with a considerable increase in compression ratio by as much as a few points, and an increase in compression cranking pressure and at the same time stop detonation issues all together running premium pump gas, all other things being equal.
 
When bike "pings" it is pre detonating. this is not good. This almost always only happens under load. To much compression or ignition advance causes this. In your situation it sounds more like run on. Some bikes simply do this to some extent. Big bores do it a lot. My WR500 yamaha does it on down hills, bing bing bing randomly. Its not an issue just irratic idle type of thing. Actual Pinging when under load is bad. You will usually find this hill climbing or under heavy acceleration. Its not good for the piston, rod, rod bearings and crank as it imposes a large load on those parts. I think your bike might be fine, maybe some carb tuning to get rid of it if it bothers you.
 
Thanks guys, I really mean that. I know its hard to say what it is with out hearing it in person. I did not have time tonight to mess with the gas but I just bought some 97 and I will mix it up next.
 
I'll take a shot. I have heard the sound you describe many times on newer bikes. We call it "lean pop on deceleration". When you "chop" the throttle and coast with the clutch out, the engine is spinning faster than what the carb is metering (throttle is closed). The pilot is the only fuel source, but because the engine is spinning fast and pulling a vacuum, it is pulling too much air for what the pilot can supply fuel.....Lean. We usually put a richer pilot in. You can try the air screw and see if that works. Jeff
 
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