Cylinder head / exhaust pipe leak

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Pharisee
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Cylinder head / exhaust pipe leak

Post by Pharisee »

The exhaust port in the cylinder head of my '55 M18S has, over the years, become enlarged to the point where the exhaust pipe fits like a pound of sausages up the Blackwall Tunnel. I've tried various 'quick fixes' including silicone sealants of various sorts including a 'high temperature' version and also a sealant designed for wood burning stove flues. The silicone sealants were no good at all... they all burned out within a few minutes. The other sealants I've tried required heat to cure them but were 'blown out' by the exhaust gases before they had a chance to cure.
A couple of days ago I tried something a little different. I cleaned the head and the pipe and resealed the joint with 'Hylomar' exhaust paste. I used a propane torch to cure the exposed paste in the joint and then slid a Triumph exhaust pipe finned clamp up to butt against the head. I started the engine and left it ticking over for about 10 minutes. Everything seemed to be ok. The finned clamp held the paste in place while it cured completely.
Took the bike out today for a 20 mile ride and that seems to have done the job. No air leaking into the exhaust and no annoying back-firing on the over-run but I was surprised by how much it had affected the carburation. The engine was definitely unhappy at small throttle openings. It was 'hunting' and made it awkward trickling through traffic. I stopped in a lay-by and had to back out the air screw on the Monobloc by a complete turn before it was running happily again.

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spookefoote1956
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Re: Cylinder head / exhaust pipe leak

Post by spookefoote1956 »

What size fin cap? I like that idea.
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Pharisee
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Re: Cylinder head / exhaust pipe leak

Post by Pharisee »

spookefoote1956 wrote:What size fin cap? I like that idea.
It's a 1.3/4" internal diameter finned clamp that I originally bought for my '71 T120R Triumph.
I'm from the Fens.... Gimme six.
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spookefoote1956
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Re: Cylinder head / exhaust pipe leak

Post by spookefoote1956 »

Looks good too. I'll have a look on ebay
Hail Joe Lucas ............ Prince of Darkness!
All my bikes are original........ to me!
"Creativity is your intelligence having fun" Albert Einstein
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spookefoote1956
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Re: Cylinder head / exhaust pipe leak

Post by spookefoote1956 »

Just ordered one, thanks for the idea.
Hail Joe Lucas ............ Prince of Darkness!
All my bikes are original........ to me!
"Creativity is your intelligence having fun" Albert Einstein
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Janet
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Re: Cylinder head / exhaust pipe leak

Post by Janet »

Pah! Vesta's had a finned clamp on its exhaust pipe for years. Where Janet leads, others follow. :lol:

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ajscomboman
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Re: Cylinder head / exhaust pipe leak

Post by ajscomboman »

Janet wrote:Where Janet leads, others follow. :lol:
Of course they do, usually with their headlights ablaze so as to illuminate the road ahead of you due to your feeble lighting. :rofl: :rofl:
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robcurrie
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Re: Cylinder head / exhaust pipe leak

Post by robcurrie »

Just don't follow Janet to Photobucket.

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Janet
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Re: Cylinder head / exhaust pipe leak

Post by Janet »

robcurrie wrote:Just don't follow Janet to Photobucket.
Why would anyone want to? I copied the picture from the Jampot website photos. Perhaps you weren't logged in there.

Here it is again, saved to my pc and then uploaded in this post. Always worth seeing a class machine. :rofl:
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Janet
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Re: Cylinder head / exhaust pipe leak

Post by Janet »

ajscomboman wrote:
Janet wrote:Where Janet leads, others follow. :lol:
Of course they do, usually with their headlights ablaze so as to illuminate the road ahead of you due to your feeble lighting. :rofl: :rofl:
Just think how useful it would have been if there had been a big van with huge lights behind me but there was none to be seen. I wonder why that was. :twisted:
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