Rear exhaust header

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andybaggies
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Rear exhaust header

Post by andybaggies » Wed Apr 26, 2017 8:11 am

Sounds like i've got a farting exhaust at the rear and at the moment I'm not too sure if it's coming from the join with the head or the union with the rest of the exhaust system.

Either way is it possible to remove just the rear small header piece, replace the gaskets & refit without removing the rest of the system i.e removing the front header?

I suspect I know the answer but I'm dreading removing the bolts on the front :( After 17 years and two winters riding you just know they are going to be absolutely 'kin solid :x As it is the rears are going to be bad enough if only from an access perspective.

BTW is the pair valve pipe held by studs or bolts?

Cheers,

Andy B

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Re: Rear exhaust header

Post by Crap Tartan » Wed Apr 26, 2017 8:43 pm

you will need to remove the pipes to get the rear stub out but are you sure its coming from the head gasket and not the join gasket where it meets the rest of the pipes?
These have been known to break up and cause noise and farty stuff................

Getting access to the rear studs is a right pain, I just take the rear shock out to give me some space
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andybaggies
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Re: Rear exhaust header

Post by andybaggies » Thu Apr 27, 2017 8:10 am

I did a quick check this morning after starting him up and you're right - it's definitely coming from the union. But to replace it's gasket I still need to remove the complete system, correct?

I did notice the bolt holding the union clamp is rusted to buggery, and possibly loosened things, so I may well dremel him off and put a new one on to see if it makes a difference. Probably not :(

And I know what you mean regarding access :? a quick dry run last night shows that I may well get there with a long socket extension and additional removal of the rear wheel & hugger. It'll be good to be able to get the 'ol magic impact wrench on 'em.

Still fearful of the front ones being seized solid and have to helicoil them but I'd be really buggered if the same happened at the rear :cry:

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Re: Rear exhaust header

Post by Crap Tartan » Thu Apr 27, 2017 11:40 am

defo need to drop the pipes to do the union but you dont need to take the rear stub off, maybe just loosen a little to make it easier.

Give the front ones a good soak in penetrating fluid the night before and dont rush it, i have never had a problem removing mine but then again they have been off/on rather a lot!!!

A good time to give them a good clean too!
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andybaggies
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Re: Rear exhaust header

Post by andybaggies » Thu Apr 27, 2017 8:20 pm

defo need to drop the pipes to do the union but you dont need to take the rear stub off, maybe just loosen a little to make it easier.
Ahh, I understand now :doh: ! If I do have have to loosen the bolts I might as well take 'em out to clean with a good dollop of anti seize on re-assembly.
Give the front ones a good soak in penetrating fluid the night before and dont rush it, i have never had a problem removing mine but then again they have been off/on rather a lot!!!
Yep I hear you re rushing as I'm an old enough fart to remember too many times when I didn't and made a right pig's ear. Experience I think they call it.

BTW I did some research on penetrating fluids & I reckon I'm going to go home made with nail polish remover, aka acetone, mixed with veg oil. Some use ATF instead of the oil but for me that's not easily to hand. Will probably give it soak every night for a good week before hand also.

The impact driver hasn't failed me yet & I reckon a quick braapp should get it going. And of course lashings of anti seize and probably new bolts on re-assembly.

Cheers,

Andy B

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Re: Rear exhaust header

Post by andybaggies » Sun Jul 23, 2017 6:05 pm

Well I've finally got round to replacing the rear exhaust union gasket/seal and all went well with the feared front exhaust bolts. Hurrah :D

I ended up using PlusGas, online consensus seemed to think it was the best, every night immediately after I parked up and also just before tucking him up for the night. I did this for a good couple of months before plucking up courage to have a go.

A last minute conversation with a mechanic recommended not to use an impact driver as they could damage the allen key bolt holes (rather than the thread). He advised running the engine up to temp then working them loose carefully with manual tools & feel so I used a good quality allen socket and a breaker bar. As the silencers where already off I tried with a cold engine & much to my surprise one of them moved within 2 secs and the other within a minute of gentle pressure with a delightful mini 'crack!' Tough to say how much the PlusGas regime helped though.

The rear union clamp bolt disintegrated at just the mere sight of an allen socket but was easy enough to dremel off (rear wheel removed).

Replacing proved tricky as CT mentioned the rear stub needs a little movement to align front and back at the same time. But as I didn't want to push my luck on the rear header bolts, not to mention being a real pain to access, I managed by first fitting it at the front and then at the rear with a little judicial & careful levering.

Assembled with a stainless clamp at the rear and stainless studs at the front with brass sockets. Much copper slip used as well.

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Re: Rear exhaust header

Post by shebee » Sun Jul 23, 2017 8:41 pm

:thumbsup: :thumbsup:
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Re: Rear exhaust header

Post by nickst4 » Mon Jul 24, 2017 7:54 am

Glad you got it sorted, Andy. I replaced the back header screws with S/S hex heads to give easier access than the socket-heads. It sounds contrary, but the hex-heads are both shallower and more reliable.

My front p-air stub is now attached with S/S 6mm socket-heads, but with a solid gasket beneath to defeat the p-air function. I've done this to cool the exhaust gasses and hopefully reduce header corrosion. You only have to look into the exhaust ports to see how much hotter the p-air side gets. Obviously, this may be environmentally-evil in terms of emissions, but it hasn't had ANY other effect on running. I'll do the rear one sometime. Are you thinking of doing the same? Maybe you have aftermarket cans?

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Re: Rear exhaust header

Post by andybaggies » Mon Jul 24, 2017 9:19 am

Glad you got it sorted, Andy. I replaced the back header screws with S/S hex heads to give easier access than the socket-heads. It sounds contrary, but the hex-heads are both shallower and more reliable.
When I do get round to doing the rears I'll be doing the same, S/S studs with brass nuts.
My front p-air stub is now attached with S/S 6mm socket-heads, but with a solid gasket beneath to defeat the p-air function. I've done this to cool the exhaust gasses and hopefully reduce header corrosion. You only have to look into the exhaust ports to see how much hotter the p-air side gets. Obviously, this may be environmentally-evil in terms of emissions, but it hasn't had ANY other effect on running. I'll do the rear one sometime.
I did think of doing this as well but no, lets just do one thing at a time and reduce the possible pig's ear opportunities. I'll leave this for another day, perhaps when the rear wheel is out for a tyre change, and do them both at the same time.
Maybe you have aftermarket cans?
Nope, standard cans for me and if the truth be known aftermarket cans are great for blatting about (exiting roundabouts, under bridges etc) but on a commute they can soon become wearing especially on a motorway (drone). Plus I haven't seen any that look right under the hangers and come with link pipes that bolt to the frame (as the standards do).

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Re: Rear exhaust header

Post by nickst4 » Tue Jul 25, 2017 8:24 am

Andy,

+1 on your view of aftermarket loud exhausts, especially since (for me at least) most of the exhaust sound is excluded by an efficient helmet and custom earplugs worn to defeat wind noise. "Loud exhausts save lives" is just an excuse to be antisocial, IMO! :nod:

I was just wondering about your original p-air comment because I suspect some owners defeat it in an attempt to civilise aftermarket exhausts that don't match the fuelling regime developed by the bike's manufacturers. Your mention of p-air disablement is the first to show after a request for comments way back.

Nick

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Re: Rear exhaust header

Post by nickst4 » Wed Jul 26, 2017 8:14 am

Andy,

A thought occurs: while stainless studs and brass nuts on the rear exhaust port sounds like a good idea, I think you might find it impossible to get the system offered-up with studs sticking out. I know I struggled with getting it all back in place after having it polished. It might be easier if the swingarm was removed but that would make exhaust work even more exhausting... :roll:

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Re: Rear exhaust header

Post by andybaggies » Wed Jul 26, 2017 12:25 pm

I was just wondering about your original p-air comment because I suspect some owners defeat it in an attempt to civilise aftermarket exhausts that don't match the fuelling regime developed by the bike's manufacturers. Your mention of p-air disablement is the first to show after a request for comments way back.
Yes, I believe you're correct in saying the Pair system is often removed because it causes backfire with freer flowing cans on. But in my case it's just a case of removing unnecessary & unsightly junk. Not to metion having less to (not) clean & polish :)
A thought occurs: while stainless studs and brass nuts on the rear exhaust port sounds like a good idea, I think you might find it impossible to get the system offered-up with studs sticking out. I know I struggled with getting it all back in place after having it polished. It might be easier if the swingarm was removed but that would make exhaust work even more exhausting... :roll:
The same thought had occured to me also. But as is my way I usually need a good 6 months to sort out a plan of action before diving in. Removal of the swingarm does have the advantage of allowing it's bearing to be replaced.
Sounds like a 5 day over the christmas hols job to me...

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