exhaust repacking

[barney]

Good morning guys and girls , just a question .
How often do you repack you exhaust ?
I’ve got a 06 Uly with an aftermarket exhaust ( big oval) so basically a race exhaust, straight through system . whilst carrying out a service , I decided to remove for repacking , whilst at the widest part of exhaust there was plenty of packing still there , this was vastly reduced around the perf tube and the centre of the silencer therefore being an oval shape not much at all between perf tube and narrow part of oval,
So how often do / or should we repack exhaust , I am going to be using Acousta-fil , the perf tube already has a fine stainless steel mesh over the outside to help with longevity of packing .

[gusm2]

It's one of those things that you don't really notice as it gradually gets a little louder as the packing blows out, as for how often IIRC I'd be doing the V&H on mine probably once a year again depending on how much and how hard you ride it.
However I haven't had that particular problem for a while

[delw]

I used to do my Big Oval every 2 years, usually prompted by MOT advisory.

[barney]

approx how many miles was that del , as you used to do a lot more miles a year than me , and how much packing was still in silencer . ?

[delw]

Was averaging 4000miles per year. Usually had lost about 50% of the packing.

[Nutah]

to be honest as I have spent 40 years in heavy engineering
my hearing is probably fubared anyway

if your bike fails an mot or a track day test...

otherwise "Loud pipes saves lives"

[Jazzbutcher]

100% agree.

[barney]

Going to be interesting in years to come with electric bikes ( no loud pipes )
Anyways my exhaust removed , repacked and just got back from 60mile ride and noticeable difference .
Upon removal of silencer the stainless steel silencer had a gold coloured patch on the top of the silencer and in the centre line presumable due from the lack of packing , no packing around perf tube, plenty at the wide part of the oval silencer
after repacking and starting and allowing to warm up whilst I get my motorcycle gear on , no need to catch throttle and put a few revs on as before for fear of it cutting out , exhaust note is deeper not as harsh .
Took it steady for first few miles give it time to warm up the exhaust packing and expand. it felt a lot better low down, smoother more responsive around 2000rpm once warmed up and over 3000 got the usual Hum, reminds me of old war films and Lancaster’s cruising along on bombing run.
And once you get into the job its only a couple of hours work .

[gusm2]

result

[Jazzbutcher]

Thanks for the write up barney, sounds like it all went ok.
Did you undo both ends of the can to wrap the perf tube & were they pop rivetted?
Thanks.
Sounds like great result with yours

[barney]

morning Paul
I just removed the 6 Allen bolts to remove outlet pipe and perf tube came out with it , then drill out the pop rivets ( 4mm) and remove same end cap .
once apart I could measure the length of perf tube 400mm , and height and width of can , got my packing from Demon tweeks and they had a table of exhaust dimensions so you could work out how much to order although my can was in-between sizes so just ordered the larger length and cut to requirements (did end up being about 1.5m length .
measured the thickness of the silencer metal and the end can aluminium cap then add 1.5 times pop rivet diameter for correct length and correct crush when fitted, mine were 4mm x10mm stainless steel pop rivets from ebay I did order some 8mm length ones, as was concerned about a couple of then on the small part of can 12oclock and 6 o’clock positon might interfere with end pipe screws , but all was ok with 10mm length .
the aluminium end cap had got some erosion on the flange where it mates to stainless can, so cleaned up ( wire brush ) , primed with etch primer and a coat of heat proof paint ( stove, log burner paint, just what I had on the shelf ) hopefully should stop or slow down any more reaction between dissimilar metals and the elements .
Loosely fit perf tube in end cap
due to the oval nature of the can I first wrapped the perf tube with a 1m length of packing this was about the correct size for the smallest part of oval , I counted how many times it had gone around perf tube and then cut lengths of packing 400mm x 100-150mm from the other sheet of packing material , then unwrap perf tube and re wrap adding the strips at 3oclock and 9oclock position this now gave me a nice oval shape of packing , bit of masking tape to hold in place and it slid in nice , little bit a slight adjustment ( rocking from side to side ) of end pipe to get perf tube to engage with the other end in can and she was in , then just bolt up and pop rivet up and jobs done .

[Jazzbutcher]

Thanks Barney,
I'll get the end cap drilled off then as it looks like rain for the next few days. I'm not sure of the inner construction of the Torque Hammer, so need to see that before ordering the wool.
It sounds like the expanding stuff worked great for you, so I may try the same.
I was a little worried about the pop rivets & realigning them as I've had trouble with them before, did you put them all in to align the end and then pop them after?
Thanks for the more detailed write up that was a great help. Paul.

[barney]

yes Paul, good enginerring practice to put all rivets , bolts in before tightening , cos sods law there's always one that needs a little wriggle room to line up .
have a look on youtube for torque hammer you might be lucky and find one being striped and repacked .
with the expanding wrap stuff remember to NOT pack to tight it needs room to expand .

[Jazzbutcher]

Aye, it's also good engineering practice to make sure you have all the tools to complete the job.
I tried both my pop riveters before I started, neither pair works properly. Bo****ks!
It does look fine outside though, so I'll get my bike out instead and F*** fixing anything for today.

[Jazzbutcher]

Hi Barney,
What pop riveting gun have you got, both mine are crap & I need a decent one to do the stainless
rivets. You seemed to manage ok with yours. Does yours have a name on so I can get one the same or similar? Or can anyone recommend a decent one? Thanks Paul