Hello Eugene, no worries man, I work for a Mack/Volvo dealer are I deal with tech support/engineering all the time. I understand your frustration. As luck would have it I was a few county's over and on a whim stopped into the local Husqvarna dealer (Carolina Small Engine). They had a brand new 3120xp on the shelf and it had BOLTS in the muffler!!!!!!! The owner looked up the parts by serial number and had 2 on the shelf! The part number is 579091601. So if it ever runs across you desk again you will have it. Thanks again for your help!
here is a picture of the bolt (locked in my caliper set)
Hello Eugene, pulled the last bolt and measured. It is a 10mm hex head, 4.468" long, .232" diameter, .895" of threads on the bolt.
Thank you Eugene, I will check and let you know!
Hello Eugene, I followed your lead, checked all bolts and inspected for cracks and leaks. Checked primary and secondary compression once again all passed with flying colors! Thanks for the Walbro manual! I pulled the carb down totaly gutted cleaned set all the meter valve heighths. Got the unit all back together and it is running BETTER THAN NEW! Thanks a ton for your time and help! Husq ROCKS!
Hello Eugene, thank you for the quick response. I took your advise and purchased several plugs. gaped to spec and the same result with all three. I pulled the trigger and ordered a coil. Installed OEM coil assy. and the issue is WAYYYYY less but at full throttle i still have a whisper of a miss. You notice a bit of a viberation that comes in and out. No knocking noise as before or rough idle. The carb acts like it needs adjusted, but on this model there are no mixture screws to adjust. Thoughts?