sealing header pipe at head

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sealing header pipe at head

Post by steve m » Sat Dec 04, 2010 4:37 am

hi all,
i'm sick of it and the friends i ride with are sick of it. that annoying backfire every time on the overrun.
i've had a seal there long enough to eliminate the pilot mixture as the cause and there's no air leaks elsewhere. after 15mins to 1/2hr of enjoyable riding. bang, poppapoppoppop, bang, etc. and black soot around the joint. :( :(
ive tried loctite 510 flange sealant, 518 flange sealant, permatec muffler & tailpipe sealer, crc maniseal and combinations of all. i've also squared up the end of the pipe (which was way out) and spaced the front mount to suit.
has anyone out there tried the M&T method of fitting a steel spigot/sleeve into the port?
what have we done out there to fix this problem? i'm all ears and hoping i've missed an easy fix <209 <209
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Re: sealing header pipe at head

Post by B44R » Sat Dec 04, 2010 7:29 am

You could try high temp silicon sealant, combined with a finned ring on the pipe to help stop it being blown out.

CB...

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Re: sealing header pipe at head

Post by gunnag » Sat Dec 04, 2010 9:55 am

Apparantly the best high temp silicone is permatex ultra copper look here
Last edited by gunnag on Sun Dec 05, 2010 10:56 am, edited 2 times in total.

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Re: sealing header pipe at head

Post by Mark Cook » Sat Dec 04, 2010 10:13 am

Richen the idle mixture a touch, I expect that will cure the banging on shut down

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Re: sealing header pipe at head

Post by minetymenace » Sat Dec 04, 2010 1:37 pm

I guess the M&T method is similar to that used on the tripples. Every four or five hundred miles I have to take the pipes off and check/tighten those little beauties, maybe I should stick them in with the coppery stuff....
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Re: sealing header pipe at head

Post by SteveS » Sat Dec 04, 2010 2:07 pm

Hi

The B50 motor I got last year has a spigot in the head. How does the exhaust fit to it? Is it just a push fit over it?
Head Spigot B50.jpg
Steve - best follow Mark's advice first - it's the easiest option

Regards Steve
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Re: sealing header pipe at head

Post by minetymenace » Sat Dec 04, 2010 2:17 pm

Is that made of Brass?

Normaly the exhaust is slotted and fits over the spiggot and is then clamped on with a finned clamp. But that spiggot is slotted shurely the exhaust dosn't go inside!!
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Re: sealing header pipe at head

Post by hhh » Sat Dec 04, 2010 6:28 pm

I shim with a tomato can slathered in regular grey silicone.

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Re: sealing header pipe at head

Post by HPbyStan » Sat Dec 04, 2010 7:01 pm

Usually the port is too big allowing the gases an easy exit around the pipe as well is through it. I bore out the part the pipe slides into and then have the pipe expanded to fit at a muffler shop. You can't go too far on this because if you get the pipe a lot bigger then the port for an inch or so, you've just made an anti reversion system. It's all good.... HP

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Re: sealing header pipe at head

Post by SteveS » Sat Dec 04, 2010 7:54 pm

Hi Stan

Hope you're keeping well, good to see you posting.

Found the following on the internet:

“Primary pipes in the exhaust manifold should match the exhaust port diameter on the cylinder head; but to reduce reversion, a primary pipe that is slightly larger than the exhaust port is better. Reversion is the flow of exhaust gasses back into the combustion chamber when the downward movement of the piston creates a vacuum in the cylinder. The exhaust valves are still open when the intake stroke begins.This presents the potential for exhaust gasses to be drawn back into the combustion chamber when the piston moves down the cylinder. Any exhaust gases that are drawn into the combustion chamber will displace the air/fuel mixture being drawn in through the intakes valves and will increase the temperature in the combustion chamber, thus reducing the volumetric efficiency of the engine, as well as engine power. Preventing reversion will reduce the contamination of the air/fuel mixture by the spent exhaust gasses and will improve the efficiency of the engine.”
Reversion Cone.jpg
reversion.JPG
Regards Steve

PS Gerry it's steel - not brass - must be the reflection off my stash of gold
Steve Sewell

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Re: sealing header pipe at head

Post by HPbyStan » Sat Dec 04, 2010 8:05 pm

What do you know, my quarter century of running a flow bench wasn't totally wasted :-)

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Re: sealing header pipe at head

Post by steve m » Sat Dec 04, 2010 10:54 pm

forgot to mention i've tried permatex ultra-copper, close....but no cigar :roll: .
the standard setup is anti-reversionary, ie. pipe is larger than port and there is a step at the junction, so that's one good thing. :thumb :thumb . i guess running a bigger port might lose too much of that step and so create a problem, but otherwise it's not TOO bad a setup. as Ed has often said, it's the front bracket that is the real problem, this allows the pipe to move in the port and wear the port oval. springs to hold the pipe firm to the inside of the step in the port is the answer here, it seems, but it's all too late if your port is oval (as mine seems to be).
the M&T setup is a steel spigot, but the only picture i have shows a very small length of the spigot protruding from the head, say, 1/4". so, not that obvious if pipe goes inside or outside. if inside, then spigot is visible, why not make it flush with port. if outside you certainly couldn't clamp to it, but you could use springs to hold the pipe to the head surface of the port, and i have seen pictures of M&T bikes using springs, so, i don't know.
high temp silicone burns or blows out, the loctite 510 is high temp, high pressure and is the best i've tried but still burns. the CRC maniseal is a silicone like goo with sodium silicate added and it swells in situ with heat and sets like a ceramic so eventually it cracks and blows out. there doesn't seem to be a one product fix.
i will try richening the pilot mix, though what that will do to hot startups will be interesting <209 <209

steve

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Re: sealing header pipe at head

Post by Mark Cook » Sat Dec 04, 2010 11:07 pm

Dump the bracket. Find a good miller and have the port opened up to take a steel liner. If he or she is good it'll take less than an hour. Fit a couple of springs and Bob's your Auntie.
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Re: sealing header pipe at head

Post by britgaskets » Sat Dec 04, 2010 11:15 pm

Now this is a thread! My bike has some high performance :laugh popping now too, nothing bang bang but still not right. Bring on the Anti inversion! I could get the tig girl to fab up that for my bike next! SteveM
Thanks for explaining and the pics. Hardley Vrod squeezes down the E tube as well I think I read. Can one incorporate the 1-3/8" 441 pipe at head then build a 1-1/2" volumetric doo-hickey then taper back to 1-3/8" or leave the 1.5" for expansion of exhaust with a good muffler back pressure level?
Silicones? even with permatex grey on the header and cured then slip fit in it only lasted 40 miles on my best try ;o( the asbestos muffler patch is to gross to even deal with cleaning off but can work as can the fiberglass repair tape but stay away from it as it gets gooey with heat.
I am just getting motivated to go out and deal with that exact issue and the 0 temps it seems but will use brass shim stock. The pop can aluminum just brittizes sp LOL! and leaks anyways :roll: but will last a good long time. The esthetic issue of shimming and have to hose clamp or collar the blow out pressure always loosens as the red locktite gets heated I think and if the mounting bolts are loose the gap can get up to 1-1/2" slow modification but good budget cost :laugh
Steve
Stupid me I just bought a 15 000m '69 R3 and will have 3 pipes to deal with! less than I paid for the '67 441 basket. I think it is not going to be riding a while, insurance will be same 400cc-750cc rate $50/month. Hope to keep it but it would go before my unit singles mark my words. The ray gun muffler may trick out my 441 nice too! :laugh I got a '72 T160 as well both are papered and legal, I think I will sell the T160 pistons to a unit 250 guy first! then I will deconstruct the Triumph to heal the BSA or flog it as a rocket 3 Triumph. LOL! Long live BSA!
bikes_002.jpg
Looks a lot like this BSA B50 I thought, one of the best styled racers I have ever seen despite the Suzuk? tank?.
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Re: sealing header pipe at head

Post by 2manyrides » Sun Dec 05, 2010 4:51 pm

How embarrasing to have your <069 back fire when you are out in public!

Try this link...
viewtopic.php?f=3&t=2661#p19582
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74 TR5MX bought in 77-new, I'm the original owner

Which one to ride today?

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Re: sealing header pipe at head

Post by Grouty » Sun Dec 05, 2010 8:53 pm

I had exactly the same problem with the CCM. Silicone would just last a meeting before it blew out. Great for scaring two strokes !
The Permatex Ultra Copper would last two meetings. Mark helped by repairing the front pipe where it fits the head.

I finally solved it by welding a small stainless hook on the pipe, drilling a small hole in one of the fins above the port and fitting an exhaust spring. Now it has lasted all season, and is still going strong.
Part of the problem lies with the design of the pipe. It is held by the bendy bracket fixed to the front engine mount. Over time the pipe vibrates in the head and wears the alloy. This makes it leak worse as time goes on.

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Re: sealing header pipe at head

Post by BSA_WM20 » Sun Dec 05, 2010 10:19 pm

I had my exhaust port milled just enough to make it round again and the machinist took this down to make a little shoulder.
Next was down to the exhaust shop to get the header expanded to an interfearence fit.
Back home, warm the head slip in the pipe bobs yer uncle .
I ride with a lot of blokes with manual timing so banging & popping on the over run is par for the course.
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Re: sealing header pipe at head

Post by beat » Sun Dec 05, 2010 10:54 pm

forget al the chemistry on this point. nothing will last for long, exept you are running your engine only in tickover al the time, ore beter, it stands in a Museum for the rest of its live :!:
the solution can be only by a proper mechanical fit and do not forget to put a high temperature GREASE ( like GRAFIT ore TREADGARD ore something other wich reaches ad least 650 ° C ) on it by fitting the pipe.
this reduces the wearing out of the alu on the head, wich is given by bracket fixating ore spring fit, what ever is your joyce.
beat

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Re: sealing header pipe at head

Post by BSAJIP » Mon Dec 06, 2010 10:58 am

Steve,

I used the exhaust sealant , a gray colored putty, with success, but, I also added an additional exhaust pipe clamp. This prevents the pipes from moving. Along with the sealer, I've had no troubles. BSAJIP
Last edited by BSAJIP on Mon Dec 06, 2010 3:39 pm, edited 1 time in total.

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Re: sealing header pipe at head

Post by BSA_WM20 » Mon Dec 06, 2010 12:39 pm

If you fit an exhaust clamp ring then weld a little ring onto the header just a bit further down the pipe than the head,
Cut a corrosponding step in the exhaust collar ( some actually already have them in there).
Drill a small hole in a fin under the exhaust port.
Run a piece of lock wire from the bolt to the hole and twist.
Almost invisible.
Or drill a hole in cone of the collar fins and one in a head fin on both sides of the pipe and put a couple of springs in there.
Not so elegant but very effective.
And yes don't forget the nickel ( high temp ) anti sieze, particularly if you try my previous and use a slight interference fit or you will never get the header back off when they have shrunk together.
Bike Beesa
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Re: sealing header pipe at head

Post by gunnag » Mon Dec 06, 2010 3:14 pm

Ive got an idea about making a decent exhaust seal the same way some Nortons and bevel drive Ducatis use.

On these bikes, the exhaust pipe has a round flange on the end where it meets the port. A finned ring screws into the exhaust port pressing the flange securley in to the head similar to this. Often a round gasket is used ensure the exhaust flange is leak free.

I think this would be an easy mod to do and would only need a) the exhaust port threading to accept a suitable screw in finned ring & b) a round flange welded onto the end of the exhaust pipe.

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Re: sealing header pipe at head

Post by minetymenace » Mon Dec 06, 2010 3:49 pm

My Guzzi has somthing similar however the collet is not threadded into the head, instead the head has a couple of studs and nuts run on the studs pinch up the collet, wish I had thought of this before I got my head together!!
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Re: sealing header pipe at head

Post by Mark Cook » Mon Dec 06, 2010 5:52 pm

The stud setup we used to use on the Norton, because the threads in the ports strip due to the head getting hot and expanding away from the rings. As long as the pipe is a snug fit in the head they are trouble free.
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Re: sealing header pipe at head

Post by blaise » Thu Jun 27, 2013 11:25 pm

Mark Cook wrote:Dump the bracket. Find a good miller and have the port opened up to take a steel liner. If he or she is good it'll take less than an hour. Fit a couple of springs and Bob's your Auntie.
Mark, do you have a photo of this modification, or some input? It sounds like the way to go.

I found this one from you:

Image

Thanks,

Blaise

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Re: sealing header pipe at head

Post by Mark Cook » Fri Jun 28, 2013 9:29 am

There is no liner in there Blaise. It's a very simple job. If the machinist doesn't know what you are on about they are not good enough for the job. (or one of you has a problem with english ;-) :???: )
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Re: sealing header pipe at head

Post by steve m » Sat Jun 29, 2013 5:22 am

Copy of BILD5068.JPG
Copy of BILD5069.JPG
Copy of BILD5071.JPG
i have posted a description of the process somewhere recently, i will try and find it or repeat.

steve
PS. :shock: wow, close-ups make things look more disgusting than i really want to know :!: :cry:

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Re: sealing header pipe at head

Post by steve m » Sat Jun 29, 2013 6:02 am

viewtopic.php?f=3&t=5245&hilit=exhaust+port

this will link with Skippy's post on the same subject.

in the pics above there is a gap between the liner and the head, there is no leak and this is the first time i've seen it. the whitish stuff is anti-sieze as after many thousands of miles i have only recently removed the pipe for the first time and it is such a tight sliding fit, steel-to-steel, i'm glad i put some on originally. no sealer is required, there is no leak to seal for.
if i can paraphrase Mark "if the engineer cannot understand what you want then you're in the wrong shop".
below are pics of the jig that my mate and i made/used to fix my head. have a look now, so you know what this is all about.
start with large piece of flat plate, place head on it with the exhaust port lined up pointing straight off the long end (parallel with the long sides and hanging over the short side) make a line some distance off the other side where the bend will go (don't mark it too close to the head, when you bend you loose at least the thickness of the material).
now, mark and drill 3-4 holes that line up with the stud holes in the head, i used one of the pushrod tunnel stud holes because it's a lot easier (and i love doing things the easy way ;-) ). put a bend in the plate on the mark you made roughly right angle .
now, you have to make a plug exactly to fit in the exhaust port with a stem on it to fit the thingy you put in the tail stock of your lathe. this is very tricky as your port is oval, wobble, wooble you need to make some judgements.
next, get yourself some real heavy gauge tubing or rod, 4-5 inches of.
bolt the head to the angled plate, place the plug in the port and fit the stem into the said "thingy" on the tail stock, wobble, wobble you need to make some judgements. place the heavy tubing/rod into the chuck and bring the plate/head upto it, together. you may have to profile the end of the tube/rod to get it close enough to weld.
when you are satisfied that all is concentric, weld the tube to the plate and remove the plug.
now you can turn the inside of the exhaust port out to whatever diam. you want.
Stan's fix is the easiest but, i think, the problem will show again sadly, but(again) if you only take a little out, to get the port circular again, you could do this many times before serious surgery would be required. how many miles do you do?
one problem i had was that we were limited by my tightassedness, to what my mate had to hand, as far as materials went (i'll explain later).
so, next you need to turn up the sleeve, which will need to be a tight interference fit in the port on the outside diam. and a tight sliding fit for the exhaust pipe on the inside diam. my sleeve has a lip on the inside end that the pipe butts upto and the diam. of this is smaller than the pipe diam. so i still have the anti-reversion lip. you also need to make the final length a little longer than the port so you can have something to press on right upto the finish.
next, you want to replace the part of the crap tubing that goes into the port with a piece of turned steel the same size (aiming for tight sliding fit in sleeve), just an inch or so and weld your pipe to this after cutting the equivalent length off and profiling (lotsa care here!).
that's all there is too it.
you need to think it through. you need to do a fare bit of measuring and you need to guess/know about allowing for expansion in heated steel (once you put the sleeve in - that's it, you'll never get it out again)(need a smilie with that flip/flop hand gesture).
this is a guide only - the best description i can....describe.
oh yes, and you'll need a knowledgeable,tolerant mate (mates for over 40 years but we still faced up once during this day - funny now, looking back :oops: ) that is prepared to spend a lot of time. it took us all day.
i do about 7-8000 miles a year on my B50, so for me this was worth doing, but as i'm typing this i am really warming to Stan's method :thumb.
once you take the head off the plate that's it. next time you will have to separate the plate and heavy tube/rod and set up again with another plug that suits the next oval ported head.
<201 and if an engineer can't understand all that then you're probably in the right shop :???: :roll:

steve
:oops: forgot to mention - have your lathe turning very slow as it is a large unbalanced lump spinning.
hope you all find this interesting
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BILD5073.JPG
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Re: sealing header pipe at head

Post by Nambo » Sun Jun 30, 2013 10:28 am

SteveS wrote:Hi

The B50 motor I got last year has a spigot in the head. How does the exhaust fit to it? Is it just a push fit over it?
Head Spigot B50.jpg
Steve - best follow Mark's advice first - it's the easiest option

Regards Steve
My Commando has this.
The exhaust pipe doesnt push over it, it pushes into it!
You have to have an exhaust finned clamp that can slide over that brass spigot, so that when it is tightened up, it tightens the brass spigot so that it grips the exhaust pipe, works quite well on my Commando.

Now what I have done on my B44 for the thread problem of an oval exhaust port, my friend has done it on his TR25, we purchased the screw in steel exhaust spigot for a Triumph Daytona T100R, took the head to an engineer who tapped a thread for the spigot in the head. A simple job that cost about £25, its just the right size for the B44, the B50 is slightly bigger though so you would have to measure maybe a 650 Bonneville spigot to see if it would still work.

Then for the pipe, Armours sold me the end bell shape that they would normally weld onto a T100 exhaust pipe.
I cut the end off my B44 pipe so that it just contacted the end of the now fitting spigot, slid the part from Armours over the pipe and spigot, held it in place with a bit of JB weld so that the welder could then weld it properly.

Maybe you can make it out in this picture?

Image

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Re: sealing header pipe at head

Post by oifman » Thu Jul 18, 2013 12:29 pm

Just thought I'd add my own procedure for curing this problem:

On my machine there is quite a gap between the cylinder head and the exhaust pipe- about 0.75mm- so just using fire cement doesn't last more than a couple of miles before it's blown out.
So, I decided the split the problem in two- 1) mechanically fill the gap and 2) then seal it.

As I said, the measured gap was about 0.75 mm so I purchased some aluminium wire at 0.7mm dia via e-bay (about $10 for 30m!). I then close wound this around the end of the exhaust pipe as shown below-
IMG_2215.JPG
I start the wind about 25mm from the the open end of the pipe and finish off by pushing the wire end through a pre-drilled 1mm dia hole. It's held quite well enough.

After this I apply a thin coating of cement-
IMG_2216.JPG

and replace the exhaust pipe -
IMG_2217.JPG

I've found this method to be quite reliable- and it's still easy to remove the pipe again when to you need to.

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Re: sealing header pipe at head

Post by Canberra » Thu Jul 18, 2013 2:03 pm

Another idea I use is to get the header expanded to the size closest to the port and just drill/screw a self tapper through the outside of the port through the header. It stops the vibration problem in its tracks. The reason the sealant get blown out is the movement of the pipe due to exhaust pulses and vibration.

The use of springs also does the same job of reducing the vibration as it also means you are not relying on the front engine brace to hold the pipe in position. I do not have springs fitted or use a sealant but as my header is a low level I have a second retention bracket on the header under the motor as well.

John

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Re: sealing header pipe at head

Post by Jeff K » Tue May 08, 2018 4:03 am

Most of the BSA/Triumph 250's from around 1967 to 1970 that I have seen had a little finned aluminum clamp on the exhaust pipe. You would mount the pipe tight to the head and then slide the clamp on the pipe back until it was against the head and then tighten down the single screw in the clamp. They were so common, that I thought they all came that way from the factory.
Jeff

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Re: sealing header pipe at head

Post by twinshocker » Tue May 08, 2018 11:22 am

Final solution , no more blowby for ever :

Image

Image

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Re: sealing header pipe at head

Post by Mike A » Sat Sep 01, 2018 1:02 pm

I just flared the end of mine, turned up a bit of Ally into a shallow cone to use as a drift, heated the end of the pipe and a few light taps later one nice tight fitting pipe, it seemed the obvious answer, no big engineering job needed or anything like that, I've had no problems in the last six months so all's well so far as I'm concerned :grin:

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Re: sealing header pipe at head

Post by Jeff K » Sun Sep 02, 2018 1:25 am

Looks a lot like this BSA B50 I thought, one of the best styled racers I have ever seen despite the Suzuk? tank?.
b50racer.jpg
[/quote]

That looks a lot like a 1960's S*zuki T125 Stinger 125cc twin gas tank.
Jeff

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Re: sealing header pipe at head

Post by *beezergeezer* » Mon Oct 08, 2018 3:19 pm

I had this on my B25ss Gold Star to sort it I used some CT1 an all purpose silicone adhesive see link http://www.ct1ltd.com/our-products/ct1/
this product is very useful on my brit bikes and keeps them oil tight (even when there is oil in them)
I got some brass shim and cut it into strips, liberally applied CT1 (which comes in useful silver) to the pipe joint with pipe in place, pushed silicone in with finger and then slotted in the paper thin brass shim tapping it in to pack it tight with a cheapy jewelers type screwdriver that fitted in the gap repeated this until gap was full. then for added assurance drilled a 2mm hole in the nearby cylinder head fins either side and the same in the pipe clamp fin, while the pipe clamp was un tightened added a bit more CT1 pushed it against the head squidging out the excess ensuring a good seal the lock wired the clamp/fin to the head and tightened every thing up. I have now done over 500 miles and exhaust does not blow at the head.

CT1 is a really useful product I use it all the time. when assembling a gasket surface i apply just a very thin smear to the gasket before assembly.
It has good adhesive properties i have used it to mount a number plate. I have found although it is not heat proof as such it has still sealed my exhaust and when used on gasket surfaces it it easy to remove by rubbing over it with your finger.......http://www.ct1ltd.com/our-products/ct1/
hope this helps....Beezergeezer....

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Re: sealing header pipe at head

Post by *beezergeezer* » Thu Jan 31, 2019 5:55 pm

Today been in the shed working on restoring my B25ss Gold Star, yes i am probably that sad i am the only one who has bothered to do a full restoration....lol.....while sipping my coffee and popping the cup on the shelf i knocked off 2 Triumph exhaust stubs from my old 3ta / 5ta ,.....then it hit me, no not the exhaust stubs, but a solution to the ever leaking exhaust pipe at head problem....
The Triumph 3ta / 5ta steel exhaust stubs screw in to the Triumph Head and pipe clamps on ....no surprise there..
i picked mine up off the bench and thought I wonder.....yes they will screw in to your B25 head reasonably easy, that is if you can find or make a tap to thread your head should not be too hard.
screw in exhaust stub,
then simply NEATLY weld (there are a lot of pigeons about) a collar on you down pipe as the Triumph Clamp on type, silver chrome, black chrome or paint to suit, use exhaust clamp of your choice.. hey presto no more farting from head.....
no doubt I am not the first to discover this so no financial reimbursement is required...lol.....

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Re: sealing header pipe at head

Post by BSA_WM20 » Sat Feb 02, 2019 9:26 am

I have used the same method as Stan for decades.
Got the port trued round then got the local exhaust shop to expand the pipe till the ID of the pipe is the same as the ID of the port.
Run the ngine for a few minutes without a pipe to expand the head then slip the pipe in quickly and allow everything to cool down.
Once is is cool, poke the bolt through the front engine mount and modify the hole if needed.
Then make up a Steel spacer slightly bigger than the gap between the pipe bracket & the frame lug.
Now when you put a nut on the mounting bolt and do it up tight, the pipe is not going anywhere.

Make sure all the engine mounts are tight & stay that way, in particular the through bolt under the engine and the head steady.
Bike Beesa
Trevor

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