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Moster 185 Exhaust


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Hi Tony,

I have just had my exhaust repaired by one of our clients. After repairing, he also gave me a report into why he thinks so many of them are cracking. I was not aware of the 3-minute warm-up procedure, but I was naturally doing it as I would run my engine and then go set up my wing. My motor has roughly 30 - 35 hours.

I am relaying his words as I remember them, I am no expert: The exhaust is made in two halves by pressing/forming "thin" sheets of carbon steel into a press. When steel is formed into a mould, you send up with parts of the steel that are stretched more than others. He said that the main cause of the crack is due to the type of metal used (there are better metals, but this increases cost) and that there are parts close to the exhaust of the engine that has been stretch so much that they are wafer thin.

He said that what they could have done was to make the exhaust in more parts, reducing the amount of stretch up at the neck of the exhaust. Vortex Aero has made an aftermarket exhaust that implements this. https://www.vortexaero.com/product-page/vittorazi-moster-engine-exhaust

In my case, I had a big crack like yours and one of the springs had ripped off. He has added a new plate over the top to strengthen the neck. Before and after shots attached.

He charged me 3 hours of labour.







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3 hours ago, asquaddie said:

or just the outer shell

Are you saying there are two skins on that exhaust or are you assuming the crack does not penetrate?
Shame you are so far away, I'm charitable enough to drill and run a bead through that but I couldn't be arsed messing around with postage... you must know someone with a tig welder?
If you clean it up and drill it, I'm sure a local fab shop would run a bead through it for a few quid.

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2 minutes ago, Blackburn Mark said:

or just the outer shell

Not sure what I am saying to be honest.  It just looks like two folded pieces on top, so I was guessing it must be a double layer!!!


3 minutes ago, Blackburn Mark said:

but I couldn't be arsed messing around with postage

Thanks for that.


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A friend of a friend told me about a welder close by. The best in the South West.....

He sounded very knowledgeable and welded the exhaust as below.  All looks good, just wondering if there is a second skin and was it intact!!! 

Richard - Your first photo looks the same - I guess that was just tig welded too.   



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My only concern based on what I have been told from people is that you are meant to sand off the paint layer and drill a hole at the ends of the crack. If you do not, you will find the crack will just continue to grow. Let us know how you get on.

Looks to me like he hasn't even sanded the paint off to see how far the crack goes under the paint.

In my case I found that on the surface it looked like one line crack, but we found that under the paint it was more like a tree branch on one end of the crack.


As stated above, I am no expert, but simply welding a single line sounds too easy.

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11 minutes ago, Richard Leishman said:

Looks to me like he hasn't even sanded the paint off to see how far the crack goes under the paint.

Richard. I did watch him and he did all around the crack and then tig weld. He did not drill holes I think. 

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