I decided that at 47000 km it would probably be a good idea to decarbonise the expansion chambers with the caustic soda method. Well, in the end result on the first chamber was satisfying but now there is water trapped somewhere in the chamber! No matter how I turn the chamber, it just doesn't come out.
I can remember that I have seen pictures of NSR250 expansion chambers cut in half and that they chambers have two concentrical shells with some space between them. So I have drilled two 1 mm holes in the outer shell in the hope that I would hit the cavity but of course I wasn't successful. There must be more than one cavity...

Has this happened to anyone who has also cleaned their expansion chambers using the same method? How did you solve this?

I should note that my NSR is in pieces, otherwise I would just put the chambers on the bike and go for a long ride and hope that the heat would drive the water out.

Perhaps applying an external heat source may work.A blow torch should generate enough heat to evaporate the water if used carefully.

Thats what i like about you Owen, nice simple approach, cant fail to work !!!
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Lesviffer750 wrote:Thats what i like about you Owen, nice simple approach, cant fail to work !!!

well Les,seeing as I'm here at the control panel of a giant blow torch(a 260MegaWatt gas turbine),the exhaust gasses of which are used to generate steam for a 180MW steam turbine,I didn't have far to go for a solution!

By the sounds of it, you will not have the pipes back on the bike any time soon?
So you want to get rid of the water to prevent it from causing any rust I guess.

Here are some obvious/stupid suggestions:

1) Put the pipes on another bike and go for a ride
2) Get some heatproof tape and connect up a heat gun/paint stripper for a few hours
3) Put the pipes in a hot water cupboard for a month
4) Hang them in a chimney above a fireplace/furnace
5) Connect them up to the exhaust of your car and go for a drive.
6) Next time your girlfriend goes sunbathing, ask her to take the 2 pipes with her.
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[color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...

You guys probably think I'm an idiot asking such a question.

If I thought you were an idiot, I'd say it!

It gets me in to a lot of trouble, saying what I think.
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Andy.
NSR-WORLD.COM

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I apologise if my post made you think I was making fun of you.
That was not my intention. I was merely trying to be a bit silly, and perhaps a little bit helpful?
There is no such thing as a stupid question.

Someone may yet come up with a novel way to help you out.
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[color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...

TuckerBag wrote:I apologise if my post made you think I was making fun of you.
That was not my intention. I was merely trying to be a bit silly, and perhaps a little bit helpful?
There is no such thing as a stupid question.

Someone may yet come up with a novel way to help you out.

Ouch!

gepe wrote:I decided that at 47000 km it would probably be a good idea to decarbonise the expansion chambers with the caustic soda method. Well, in the end result on the first chamber was satisfying but now there is water trapped somewhere in the chamber! No matter how I turn the chamber, it just doesn't come out.
I can remember that I have seen pictures of NSR250 expansion chambers cut in half and that they chambers have two concentrical shells with some space between them. So I have drilled two 1 mm holes in the outer shell in the hope that I would hit the cavity but of course I wasn't successful. There must be more than one cavity....

The picture I remember of standard MC21 chambers, showed they had a second 'jacket' welded over them. Possibly with some kind of sound deadening material in between too.
Anyway, the jacket was removed, which lightened the pipes.
Was it Bill Limb, or Lamb who did it? Perhaps Andy or Dave Ett can tell us.
If you have got water trapped in this jacket, the best way to get them dry is to get hot air/exhaust gasses blowing through the pipes.
Failing that, store them in the warmest place/room you can find, until you can run them on the bike again.
Better still, get some Tyga stainless exhausts, and leave the originals in storage for when/if you sell the bike.

I was thinking you could spray them with UHT paint then get your local friendly powder coating company to put them in their oven.
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Why do things simply when you can complicate them

I'm no expert, but I reckon they might just dry out on their own.

Chester362 wrote:
The picture I remember of standard MC21 chambers, showed they had a second 'jacket' welded over them. Possibly with some kind of sound deadening material in between too.
Anyway, the jacket was removed, which lightened the pipes.
Was it Bill Limb, or Lamb who did it? Perhaps Andy or Dave Ett can tell us.

I have those pipes... somewhere! They were done for testing purposes, to evaluate the stock chamber design in a "derestricted" form.

As far as I am aware, the MC21 and MC28 chambers are of similar design, but only one chamber has the perforations. However, both chambers are double-skinned. The perforated section was cut out, and a new piece of sheet let into its place. The pipes performed very well, with bags of mid-range and a healthy enough peak for a standard, delimited motor, but no real usable over-rev. We have seen close to 70hp with stock MC21 chambers though (on a far from stock bike!), but they are very very fussy to set up. The stock silencers are rubbish, and the MC28 items are even worse!

None of this helps with an MC28 though, or with chambers that are retaining water!

Best solution is to fit them to the bike and run it! Simple as that.
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Andy.
NSR-WORLD.COM

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Thanks for all the good ideas, either helpful or not.

As stated, the bike is in pieces in my apartment, I don't have access to a blow torch and I don't have a girl friend.

I had actually hoped that someone knows the internal setup and where to drill a hole so the water can escape. The water probably is trapped in there because of an imperfect weld seam or something like this because only one of the two chambers has the water trapped inside.

Anyway, I don't expect further comments.

gepe wrote:I had actually hoped that someone knows the internal setup and where to drill a hole so the water can escape. The water probably is trapped in there because of an imperfect weld seam or something like this because only one of the two chambers has the water trapped inside.

Andy has explained about the perforated inner section on one chamber. This perforated section has the second, outer 'skin' welded over it.
That would make sense of why you only have water trapped in one chamber.
If you are drilling, or going to drill into the section with water trapped in it, you will have to get the hole welded up again.
If you don't weld up the hole, you will have a leak there.