Author Topic: Drilling out exhaust bolts  (Read 540 times)

Offline tobyd

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Re: Drilling out exhaust bolts
« Reply #20 on: April 16, 2019, 09:35:30 PM »
There are 4 mounts for the engine so losing one isn't the end of the world. One (bottom-center) of mine bears no load at all - you can just take the bolt out and slot it back in without any resistance - the front and rear thru-casing ones need careful application of a bottle jack to unload them for re-greasing (to avoid the picture). I lost a chunk of the rear-most mounting at the case by lamping it too hard....

You might be able to weld bead-after-bead of aluminium rod into that then grind down to re-build the front mount section but you'd be pouring a lot of heat into an oil filled box and it might go comically-then-tragically wrong :( and would look rubbish.

Offline max

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Re: Drilling out exhaust bolts
« Reply #21 on: April 16, 2019, 10:19:36 PM »
<Snip>

Oh and if you need to beat it with a mallet (wooden or rubber!) to free the head from the barrels don't hit the fins (even by mistake or in a blind rage) as they are very fragile, ask me how I know...

I was planning on using a dead blow hammer with a block of wood to spread the load on the cooling fins - I can't think of any better places to smack or see any pry points for the head?



I'm a little nervous about the condition of that front engine mount... looks pretty well gone in the picture. Anyone else feel that way or am I being paranoid?

When I first realised it wasn't supposed to look like that I was concerned, but that feeling has relaxed as I've had the bike for ~2 years now and that there are so many other mounts. I can't imagine that the original cast mounting point is hugely strong anyway from looking at its design.

Offline Numewsm

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Re: Drilling out exhaust bolts
« Reply #22 on: April 17, 2019, 01:38:23 PM »
Good to know, I'll try not to brick it too much when I hear them pop into place then! Sounds like patience is key - we'll see how much I have left by the end of this...

tobyd you were right about the parts adding up though, new crush washers and o-rings alone are coming in at silly money, let alone 25 for the head-base gasket.

On the bright side, I ventured outside and cracked the 6mm front head bolt loose yesterday to test the waters before this weekend. It took some back and forth but I got it out no problem - step 1 of many complete!

I took mine off two weeks ago to have my exhaust bolts drilled out and a broken valve guide removed, (just get a second hand head it's a lot lot cheaper!!!)
The noise when the head bolts crack loose is really arse twitching!!!  :cry: :icon_eek:  Watch out for the outside bolts as these are horrific to get going if they've  never been removed, a combination of blood, sweat, choice words and brute force got them going slowly.  The inside ones are easier but still crack initially.  you can do the outside ones first then in order for the inside ones.  Suzuki has numbered them inside. Do them in order!!  Rubber mallet tapping around the head and when you see a gap use a flat head screwdriver to slowly pry up the head.  this should keep intact the lower gasket so you don't have to change that too.  After a bit you can use your hands to wiggle/pull it up the rest.   
When you tighten, do them in the correct order little by little, 1,2, 3, 4 inside, then outside top left bottom left bottom right top right.  use a torque wrench to build up the Nm tightness in three rounds until you reach spec.  :cheers:
I ride because it gives me the space to empty my mind off all that is bad and refill it with good.

Offline max

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Re: Drilling out exhaust bolts
« Reply #23 on: April 19, 2019, 07:50:55 PM »
So I've been defeated (for now...). I expected any issues would happen after getting the exhaust off, not before.

I bought some nice new cobalt HSS drill bits, expecting to make short work of the exhaust's header bolts.

Instead, I got past their rust and no further - I didn't expect them to be hardened steel but I couldn't make any progress with them at all.

Fine, out comes the Dremel. A lot of cutting, cold chiselling and some grinding later, I had all of their heads removed and flush with the collars(?).

But then no matter how hard I tried, the collars and pipes wouldn't come out of the head. The rust from the bolts has locked the collars onto them.

Does anyone have any ideas about proceeding with this?

I've tried prying at the pipes against the frame, levering on the end can, general hammering on the pipes and collars.

Tomorrow I'll try welding some nuts onto the now flat bolt studs and see whether the heat will loosen anything up. Otherwise it may be a case of welding the nuts on and just forgetting about it all.

I'm starting to lose my enthusiasm now.
« Last Edit: April 19, 2019, 07:53:34 PM by max »

Offline tobyd

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Re: Drilling out exhaust bolts
« Reply #24 on: April 22, 2019, 08:26:44 PM »
How much of the exhaust can you dismantle? Can you separate the two downpipe sections where they join together in case they are under tension and preventing the collars releasing?

If the bolts have corroded and expanded to fill the collar-hole, as per my picture earlier of the front mount, it might be hard to free off without sacrificing the downpipe. I don't know how much help heat is once a bolt was swollen tight into place?

I assume just hacking the headers off isn't really desirable? I got into the state I was in because I needed to replace the exhaust so it didn't matter.

Offline max

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Re: Drilling out exhaust bolts
« Reply #25 on: April 22, 2019, 10:08:38 PM »
A few days late, but I cleaned up the pipe to get a good ground and started trying to weld some nuts on there. Stick welding in such an awkward position was not at all fun and I kept accidentally striking up on my ground clamp on the way to the nut.

I focused on one side but wasn't able to get a good enough weld on there - I had too much slug inclusion which led to the weld shearing each time I tried to undo it.

At this point I think I might have to admit defeat. I'll just weld the nuts back on to act as a stopper in case the collar ever comes loose.

I'll have to cut the exhaust if I want to do anything further now.

I've also got 70 worth of gaskets and bolts that I can't use now too... Don't suppose anyone is interested?  :dunno_black:


How much of the exhaust can you dismantle? Can you separate the two downpipe sections where they join together in case they are under tension and preventing the collars releasing?

If the bolts have corroded and expanded to fill the collar-hole, as per my picture earlier of the front mount, it might be hard to free off without sacrificing the downpipe. I don't know how much help heat is once a bolt was swollen tight into place?

I assume just hacking the headers off isn't really desirable? I got into the state I was in because I needed to replace the exhaust so it didn't matter.

It's the original exhaust so it's all one piece. You're right, I don't really want to cut the exhaust pipes but I think that's my only choice to progress here.

I'm considering ignoring the head now and cutting the pipes just before the Y intersection so that I can get to the centrestand bolt, then reconnect them using a clamp like this:

My only worry with those is whether it will lead to any exhaust leaks though.
« Last Edit: April 22, 2019, 10:10:07 PM by max »