The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: Brucie64 on 01.07. 2010 09:42

Title: A10 Exhaust Seal
Post by: Brucie64 on 01.07. 2010 09:42
Hi All,

Just fitted a new exhaust to my A10, it proved to be a bit of bitch to fit but thought I had got there in the end with a bit of tugging and pulling. However after a short run I noticed that the header pipes must not have sealed fully to the barrels as I had developed sooty deposits on both pipes where they join the engine. In an attempt to fix this I then took both exhausts off and tried a bit of exhaust muffer paste on each of them before refitting. The next day I again took the bike for a run only to find 10 miles down the road the exhaust pressure has blown a hole in the paste seal on one side.

1. Does anyone know if there is such a thing as a proper exhaust seal for A10 header pipes. I have seen on the interent the small bore copper washers for the Bantam header pipes and such like but as yet none for A10's?

2. If these don't exist, what does everyone else use to make sure their exhausts are airtight?

Title: Re: A10 Exhaust Seal
Post by: MG on 01.07. 2010 10:11
I'm using Loctite 5920. Worked pretty well so far, as long as the leaks are relatively small.
I also found that the cured muffler paste is too brittle and will disintegrate from the vibration.
Title: Re: A10 Exhaust Seal
Post by: bsa-bill on 01.07. 2010 10:56
never have needed anything on my Flashes, I'm thinking maybe forget about anything extra and beg, borrow or find someone with a pipe swage and expand the pipes
Title: Re: A10 Exhaust Seal
Post by: lawnmowerman on 01.07. 2010 11:26
My old system was a bit loose in the ports and the PO had used a piece of thin alloy shim about the thickness of a beer can wrapped around inside the port and stuck with a smear of exhaust paste before fitting the pipes. It seemed to work ok and was a cheap fix.
The other advantage is that it gives a genuine reason to empty a beer can before you start work   *beer*
The new system was a snug fit after shortening the pipes a bit so did not need any sealer.
Bill's suggestion is a better fix but I think you may have to heat up the pipes to avoid splitting while expanding them and it may blue the chrome.
Jim
Title: Re: A10 Exhaust Seal
Post by: alanp on 01.07. 2010 17:09
Brucie, I bought some of this stuff on ebay - Pro Seal Copper XS Hi Temp Silicone Sealant. It's suitable for temperatures up to 700 degrees F. Much to my surprise and pleasure it works a treat.
Alan
Title: Re: A10 Exhaust Seal
Post by: wilko on 02.07. 2010 01:02
Been using ordinary clear slicone for years on bikes and cars! Works a treat and heat resistant.
Title: Re: A10 Exhaust Seal
Post by: Brian on 02.07. 2010 01:05
Most automotive exhaust places have hydraulic pipe expanders, these are a multi fingered device that goes in the pipe and expands it as little or as much as you like.

I have used them to just bring a pipe back to round if its slightly oval or to expand the pipe to a nice snug fit. The ideal fit is so it needs a few taps with a plastic hammer to get the pipe in.

Another sealant that can be used and works is clear silicone (roof and gutter), one of those things that you wouldnt think would be suitable but is.
Title: Re: A10 Exhaust Seal
Post by: Brian on 02.07. 2010 01:07
Wilko we both posted at the same time, does that mean great minds think alike or two drips go down the same drain.  *smile*
Title: Re: A10 Exhaust Seal
Post by: coater87 on 02.07. 2010 05:09
 They make hand expanders, but if you have to go any real amount these require SUPER human strength, or a big vice to leave marks in the pipe and a cheater bar to bend your good wrench with. Better to spend a couple of bucks and have a shop do it...

 Silicone sealant huh? Never heard of that, and never would have thought it would work. Thats something to remember!

 Lee
Title: Re: A10 Exhaust Seal
Post by: Brucie64 on 02.07. 2010 09:25
Wow, thanks for all the responses guys.
 
I guess that will be me off to the local DIY shop tonight, do you think silicone sealant might work on the wife's gob as well.  *smile*
Title: Re: A10 Exhaust Seal
Post by: lawnmowerman on 02.07. 2010 09:48
Well it worked ok on mine with a strip of gaffa tape on top just to be safe, that is if they stop talking long enough to let it cure  ;D

Jim
Title: Re: A10 Exhaust Seal
Post by: bsa-bill on 02.07. 2010 09:49
Reckon many of us know where your coming from Bruce - but no, never still long enough for the stuff to set  *rant* *whistle*

But Jim got in before me ! so it must be true
Title: Re: A10 Exhaust Seal
Post by: muskrat on 02.07. 2010 10:56
Superglue sets quick but not good for exhausts. >:D
Cheers
Title: Re: A10 Exhaust Seal
Post by: Big Nick on 02.07. 2010 22:10
clear bathroom sealant does the job.
Title: Re: A10 Exhaust Seal
Post by: Brucie64 on 04.07. 2010 17:29
Touch wood, Loctite 5920 seems to have done the trick, a lot better than exhaust muffler paste. Just come back from a 20 mile run and seem to have no leaks so far. I guess a longer run will decide if its a permanent fix or not.