Decat pipe broke today

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Hello Richard , This happend to me in Canada when I was up there visiting you and David. You probably remember (LOL) ! OK , Asad it's really not that bad. If your stud comes out then you need a bench vise and 2 nuts to jam together on the other end of the stud. Tighten these jammed nuts into the vice jaws and then remove the header flange nut with a box end wrench. You may also need a vise-grip pliers to help hold the stud on the non-threaded section. It depends on how jammed they are. Whats happening is that you are running the flange nut so tight right up onto the non-threaded part of the stud and in effect jamming it. I wouldn't attempt this without a bench vise. Buy several Norton exhaust sealing rings and have them on hand so you can bring the pipe out enough so you aren't jamming the flange nuts . 19NM is only about 14 ft.LBs
 
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So if I’ve already overtightened the studs back into the engine and they are not tightening any further is there any easy solution for that or did I strip the receiving end of these studs and now am looking at rethreading the Head. Or a helicoil or time-sert. The stud still screws in and out easily but I either cannot get it to 19NM now or I’m being too timid to try it in fear of making the problem worse.
 
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Pull it out and check the inside of the hole . In fact remove all three nuts and studs if they come out . Then thread them in without the flange on . You should be able to get the threaded part of the stud all the way into the head and then it should tighten up when it bottoms on the non-thread section. If it keeps spinning then it may be stripped .
 
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Success! Thanks for the help! If it wasn’t for your advice I’d be bent over at a mechanics shop by now ready to shell out some serious $$. I removed the bolts completely and then screwed each one in all they way in until tight and there was no problem. When testing I only tightened to 10NM. Then took them out and put the header back in and tightened the studs to 19NM without issue. I was weary so tightened each stud slowly a few NM at a time and then it felt nice and secure. Both sides done no stud was problematic. Will retorque after a few rides next week and hope for the best.
 
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Fast Eddie

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I discovered when I fitted my Thiel Motorsport silencers that the entire exhaust system on these requires rather careful assembly.

When I first fitted the silincers I thought they just didn’t fit right as I had to stress the pipes to make the mounting points line up.

So I removed the decat link pipe, greased all joints with copper slip to allow an easy slide, and juggled the assembly process, sliding the various joints in and out until I got everything to line up with fixing mounts without any stress.

My point really is that it’s VERY easy to mount the exhausts under stress, and stress + vibration = fractures.

But it’s not only vibration that’s an issue here, the pipes are long and large diameter, they expand and contract with heat, therefore as they are rigidly mounted, they will always be under some stress.

Careful, stress free assembly is therefore a must IMHO and is something all owners should consider doing / checking.
 
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Do you think adding rubber washers/spacers at the mounting points would be of any use in dampening some of the vibration?
 
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There should already be a rubber mounting boss underneath where the decat pipe bolts to the frame . If you want to do all of the fitting that FE described above would be good. And lastly , if you are doing lots of freeway speeds you may consider not overly tightening the bracket bolt at the decat hanger like I do. I do lots of highway time . This will require a longer bolt 60mm long with two jam nuts so the bolt stays put but allows a bit of freedom to the assembly. I hope this is clear. In fact Norton may want to consider a Shoulder bolt here . This would be beneficial to the assembly and allow it to float (a bit) in the rubber boss mounting . Until then try it my way.
 
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With the Zard system I have, there is barely enough room at this spot to get a wrench in there to tighten the bolt. I’ll have to see if I could use a longer bolt and a second nut.
 
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The idea is not to make it too tight . You should be able to spin the bolt with fingers when finished. You can also look for an alternative metal locking nut (not nyloc because of exhaust heat) . Just be sure that the nut won't come off during riding.
 

StuartSF2015

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View attachment 9149 View attachment 9150 View attachment 9151 I had 80 mile ride this morning & whilst just 5 miles from home a rather loud noise occurred,pulled over and found the r/h side of decat pipe had come clean off,also u can see in the picture s that the mount has broken to.
I’ve got a fabricator guy near me that can do all things fancy with bits of metal ,inc sub contract work of F1,so I intend just to give him the bike to fix at his workshop & see if he can alter the mount anyway with more flexibility to take up the stress/load to prevent it happening again, the mount has broken b4, but that was fixed under warranty, bike now 3 years old on 16,500 miles .
Ken made his own decat pipe using the oringinal cat ,so I may even do that
Bummer! Good luck with your planned fix.
 

Fast Eddie

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Ollie at Thiel Motorsport has the solution!

New decat pipes with Uber adjustable mounting, should be easier to ensure 100% stress free mounting with this...


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It also looks like he has joined the pipes with an H section . And a different exit angle left and right .
 
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what would happen if we just don't connect it at all at the bottom? Just loosely connect with springs and let it vibrate.
 
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One of my clamps had broken once and the 961 sounded awesome when my silencer almost fell off. Richard, show us the repair.
 

BLIGHTYBRIT/SF

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Got my decat pipe back today,turned out it had a crack half way round the other pipe
That connected to L/H rear shortie,stubby, motad silencer,so this repair will do for now,also pictured is bolt/ rubber mount that Tony A mentioned,& following on from his suggestion I replaced it with a longer bolt & two nuts .
I’m off out tomorrow for 150 mile jaunt around the garden of England ( that’s the Kent countryside) will taking a pit stop at “ tagg racing “ for a suspension tweak & report on what I hope is a pleasent affordable improvement.
 

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Welds look good Richard . Should get you another 17,000 miles hopefully ?
 
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Nice repair, Richard. Glad you didn't have to pop for a new pipe. Appreciate the photos. Have a good ride.
 

Stephen_Spencer

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My centre exhaust mount failed about 4000 Km (12 months + ago). Service Manager and I made a quick assessment of the rigidity of the system without that mounting point and decided to leave it.

I have had no problems with security since. I have it in mind to have the rubberised mounting welded back on however have not got around to it. I note that my system would be somewhat lighter than the average long pipes as I had the cats removed and the innards of the cans removed by an exhaust specialist.

Steve
 

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