Author Topic: Iron head broken fin  (Read 1076 times)

Offline tiggy

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Iron head broken fin
« on: 23.05. 2015 17:28 »
I have read the other posts I could find on the topic of broken fins but would like to ask if anyone has had a satisfactory experience of a temporary repair using a product such as quicksteel or similar.
The damage is small, about 1" X 1/2", and hidden behind the exhaust down pipe so barely noticeable. I appreciate there are better and more permanent fixes but the engine is not in need of a rebore.
Any feedback on temporary repairs would be gratefully received.
Thanks
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Online Triton Thrasher

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Re: Iron head broken fin
« Reply #1 on: 23.05. 2015 17:37 »
Repair it properly by brazing or welding a piece of cast iron fin on. or ignore it and just ride the bike.
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Offline muskrat

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Re: Iron head broken fin
« Reply #2 on: 23.05. 2015 21:39 »
Yep, I'm with TT on that one.
IF you go down the temp repair route you would need an epoxy that could handle the heat about 200 C.
http://www.aremco.com/ceramic-metallic-pastes/
Cheers
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Offline trevinoz

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Re: Iron head broken fin
« Reply #3 on: 23.05. 2015 22:42 »
Musky,
 I would be very surprised if a barrel ever reached 200C.
I repaired a small break many years ago with Araldite, not the 5 minute one.
It stayed together and was still there when I blew the barrel apart at the base.
However, I would prefer a permanent fix.
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Offline muskrat

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Re: Iron head broken fin
« Reply #4 on: 24.05. 2015 05:01 »
G'day Trev.
I agree it wouldn't get quite that hot, just added safety %.
Yep I Araldited a stubborn leaky head on a merlin engined fishing trawler 20 years ago, still going.
Cheers
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Offline tiggy

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Re: Iron head broken fin
« Reply #5 on: 24.05. 2015 08:44 »
Thanks for all the useful advice.
 To be clear, I forgot to mention I don't have the missing piece of fin. The Aremco product, in particular their Pyro-Putty 2400, seems to be ideal but not readily available in the U.K. from what I can see. The only reason I mentioned Quicksteel as an example is I have half a tube left over from a different application. They claim it is good for exhaust systems and temperatures up to 240C.
I will get the job done properly in time but as the bike is not in need of a re-bore, (compression tested equal 7:1 on both cylinders), it seems a lot of expense for a small cosmetic repair.
If I decide to give it a go due to too much time on my hands, I will return to this topic and update. Hopefully in a year to say it is still o.k. and not a week later to say it has fallen off already!
Thanks again to all contributors.
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Offline duTch

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Re: Iron head broken fin
« Reply #6 on: 24.05. 2015 09:09 »

Just my two bits worth-
 
 I might have said this before, but, my whole bike is predominantly made of bits that others would have 'binned'; far-que that-!...there's busted and bent fins from the alloy head, and it runs fine....

 For what it's worth, the way I see it, I built it to ride, and it's no show piece, but constantly have all kind of folks pointing and giving thumbs up and asking 'wow what is it' (motorbike idiot..!..nah jokin') and sometimes even young guys saying their Dad had a BSA blahblah (there's no badging-for now)

 Bottom line is, fix it next time you have a chance if you really need to, and if anyone points out you have a broken fin, *smile* end the conversation

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Offline chaterlea25

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Re: Iron head broken fin
« Reply #7 on: 24.05. 2015 23:06 »
Hi All,
I have seen a fin repair on a veteran Triumph that run hotter than hell using JB weld
Its been fine for several years now *yeah*

John
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Offline muskrat

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Re: Iron head broken fin
« Reply #8 on: 25.05. 2015 09:30 »
One of my favorite products. *good3*
Cheers
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Online Greybeard

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Re: Iron head broken fin
« Reply #9 on: 25.05. 2015 19:34 »
...I Araldited a stubborn leaky head on a merlin engined fishing trawler 20 years ago, still going...

A Rolls Royce Merlin engine????!
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Offline muskrat

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Re: Iron head broken fin
« Reply #10 on: 25.05. 2015 21:15 »
G'day GB, yep all sorts of old donks in our fishing boats.
Cheers
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Online Butch (cb)

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Re: Iron head broken fin
« Reply #11 on: 26.05. 2015 10:07 »
And that would be quite tug for water skiing I would imagine.
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Offline shuswapkev

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Re: Iron head broken fin
« Reply #12 on: 31.05. 2015 06:17 »
I carve fins out of bbq plates...heaps of free ones on big garbage days...
if you get lucky...you get a plate  that is tapered...like from the outside in...saves a bunch of grinding....get the shape .... the off cuts work real nice as wedges to hold good bits in place...

 I just braze them on...acetylene...might be a few theoretical issues...but no practical ones in my case
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Offline Gerry

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Re: Iron head broken fin
« Reply #13 on: 05.06. 2015 11:44 »
Hi guys, I had a broken small fin on the left side front outer vertical adjacent to the exhaust. Easy place to get to and didn't have the broken bit (the head came like it) so I cut a piece of mild steel of the same thickness and then bent it to shape and using stainless rods arc welded it in very small tacks and leaving it to cool between tacks and peening each weld to stress relieve it each time. Used a dremel to clean up the welds and you wouldn't know its not original after powder coating. Get it too hot and it will certainly crack. Muskrat I used to work on Merlins in the 60's they were fitted to four engine York transport aircraft, bloody magnificent and the sound of all four running up would send the hairs on the back of me neck straight up. Still got my BA socket set!!! Cheers Gerry
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Offline Topdad

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Re: Iron head broken fin
« Reply #14 on: 05.06. 2015 12:18 »
Gerry , same thing for me every time I hear a merlin ,what little I've got stands up , about 5 yrs ago I fell off a push bike when a spitfire flew over me ,I'd heard that fabulous noise and then was looking for the plane that I lost control and bang right on my ar*e ,still saw the plane though !! cheers Bob.
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