Exhaust Downpipe Removal

[earywig]

Hi all,

I'm in the process of doing some major tidying up on the bike at the moment, i.e. re-powdercoating the fork sliders, fairing brackets etc., CRG levers, shim checking, carb synchronization, Samco hoses etc. ad infinitum. It's still very much a work-in progress at the moment.

Prior to fitting a Harris bellypan I thought I'd remove the downpipes and give them a good polish first - and here's my problem. I've managed to remove the exhaust flange bolts after soaking the same for about two weeks in penetrating oil - they were still bloody tight. That was stressful enough in trying not to break the studs, but I can't for the life of me get the flanges off the studs. It appears as if the previous owner had the same problem as there's evidence of something like a cold chisel being used to extract them. I've already removed the bolt which connects the downpipes from undereath the engine. It's almost as if the flange holes have been swaged around the exhaust studs.

I'm at the point of giving up, but I can't even do that because I can't re-insert the the bolt on the underside of the engine due to the downpipes having 'sprung'.

Any suggestions will be gratefully received - I'm that desperate!

Vic.

[Max]

Hose it down with that penetrating oil, or some WD40, get a good stiff block of wood and a hammer and tap around on them from different angles. Don't "tap" so hard as to bend the studs, but some good whacks will be needed. If that doesn't work, start it up (neighbors will love that...) get them warm and repeat... Try moving the pipes up and down at that lower mount point (with something to protect your hands if they're hot...).

The more often you remove them, the easier it is.

[earywig]

Thanks Max. I'll give it a go. I haven't tried running it with drag-pipes!

[trixynut]

Mate,

I had a nightmare trying to get mine off: something about the metal of the collars and studs being different and 'welding' together in the heat??

There's no real knack to it. Soaked mine very well with 3-in-1 when they were warm so it went in well, then tapped hard-ish with a rubber mallet (or wood like Max says) then used the downpipes themselves to lever the collars off as they are behind the collars near the cylinder head so can put pressure on them in the right place: wiggle them about and hit the downpipes with said rubber mallet and they eventually 'broke free'.

Soddin' nitemare job though: make sure you re-assemble with pleanty of copper grease so next time it's easier!

Dave.

[Greg]

Some say it's best to not use any kind of releasing agent, and just try to tap them off... what's causing them to stick on is the build up of aluminium oxide caused by electrolytic corrosion - the oxide builds up and compacts inside the collars and hey presto they're stuck fast! I managed to loosen one of mine by doing just that and was surprised at how much shite fell out of the hole. The other was beyond help though, and I had to chisel/dremel part of the collar off to release it. Not such a bad thing though cos when I reassembled it I turned the collar so the busted part was facing inside and not so visible.

Trix is half right when he says that you should lube them on reassembly, but there's a school of thought that says the copper in the grease simply helps speed up the corrosion process again. I drilled mine so they were quite a bit bigger than stud, so should make it easier to get them off next time.
G

[burty]

I wondered if there was some aftermarket collars available so you could fit them if you broke the originals.

I ended up angle grinding mine off - easily done, made a hell of a mess though, there was aluminium dust everywhere for months. I was fortunate in that my downpipes were cracked so I didn't really want to re-use them.

[Doyle171]

I spent two weeks trying to get mine off using all of the techniques above and then gave up. So i picked up a cheap set of downpipes off ebay, so the next job is to cut the collars off. Burty and tips you want to throw my way on this.

[earywig]

Thanks for the replies everyone. Greg, your comment about the electrolytic corrosion sounds like a good call as I found exactly the same on the fork sliders where the mudguard mounting screws reside.

Out with the rawhide mallet then!

[jerrah]

I'm currently experiencing the same problem:

Flanges stuck fast on one stud. Wacking the headers with a rubber mallet and wiggling them around results in the stud visibly flexing so it's really stuck on there. Luckily the other three are loose.

Is the TRX850.com solution to cut off the flanges with a dremel if it will not release? I was hoping to keep everything intact in case I wished to refit the original exhaust.

[bubbaad]

Take a flat chisel and grind out the middle so it will fit round the stud,,,,,like a small ball joint remover. Needs to be thin enough at the end to fit between the header and the head. Put in place and a few good whacks should see you right.

[cobbadiggabuddyblooo]

Is it gpz900 Kawasaki 2 piece flanges that you can replace them with if need be??? The old triumph I had the headers just pushed into exhaust port and I would just seal them with roof n gutter sealant. Even if you save one this will be an easy temp fix to get you around for a few days as the mount underneath and one flange will hold things Inplace..

[jerrah]

Previous owner appears to have removed (and not replaced) the lower mounting bolt so it's currently being held in place by the mufflers and the head. I've ridden to work twice now using the rust to hold the headers in place (no nuts) and it's still really stuck on the studs. I've got a mechanic mate coming over tomorrow night who's going to give it a go getting it off.

[jerrah]

Exhaust flange/clamp is off! 20 minutes of heat + two prybars and the OEM Yamaha flanges are off intact!

I was really close to cutting it off but my mechanic friend was confident (and correct) that he could get it off! So there you go, it CAN be done with a very corroded on clamp!

[cobbadiggabuddyblooo]

Good to hear, a little persistence ,heat and leverage and a lot of sweat... let us know how the akra system feels tomorrow.

[emway]

Take a flat chisel and grind out the middle so it will fit round the stud,,,,,like a small ball joint remover. Needs to be thin enough at the end to fit between the header and the head. Put in place and a few good whacks should see you right.

And lots of IMAL spray and a big hammer!!