Frustrating Issue with Copper Exhaust Nut

[EEL]

I have a 2012 Monster 1100 Evo. I'm having issues with the copper exhaust nuts that hold the exhaust to the head.

The nuts are backing out over time. Every 500 miles or so, the seems to get just loose enough to let a little bit of air thru the seal. Consequently I feel more vibration thru the pegs and bars as well as some backfiring on decel.

I've literally gone for a ride, came back, tightened the bolts and everything was back to normal.

i've already tried buying brand new ones and installing with no success. Due to the high temprature, i'm running out of ideas. and theres not enough meat remaining on the stud to allow for a double lock nut setup.

Any high temp medium loctite out there? Anyone else have this issue?

Seems like its only happening on the horizontal cylinder.

Thanks in advance.

[Speeddog]

I've not seen nor heard of this issue.

OEM exhaust?

[EEL]

Oem exhaust. I literally can take my 10mm wrench, tighten it both nuts on the front header about half a turn and the problem solves itself.

Its just annoying and I feel like one of these days i'm going to snap a stud.

[Speeddog]

Mark the nuts and the studs, see which one is turning.

Did this problem start all of a sudden?

Perhaps the gasket fell out when the pipe was off?

[EEL]

Nah. I've always seemed to have it but I didnt realize that was the issue until I added the PC-5 with autotune.

The O2 sensors would spot for exhaust leak and would constantly ask to increase fuel. Essentially the bike would suck in air when decelerating with the throttle closed.

I'm wondering if the threads on the studs are worn out.

[ducpainter]

I'm not seeing how the threads on a steel stud would be worn from a copper nut.

Perhaps they were always out of spec if you've always had the issue.

[Howie]

Get yourself some brand new self locking copper nuts at a good auto parts store.  The kind that are oval on top.  Like these

http://www.frsport.com/DIF-10422-Copper-Metric-Flange-Exhaust-Lock-Nut-M8-x-1-25_p_26456.html  They come in flange style too.

Also mark the nut and stud, as Speeddog said.  If the stud is backing out you can try stud and bearing thread lock.

[EEL]

Thanks I'll look into those. I've been buying new ducati one's to no avail.

The studs are rock solid so no issues there.