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Post subject: helicoil SCREAM and exhuast blowing :(
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WelshD1K  Suburban Commuter Joined: 02 Jun 2008 Total posts: 57 Location: south wales |
ok so my n1 was gonna gofor an mot tomorrow so i bought new studs gaskets etc for it instead of the mix nd match bolts that where holding the pipes in. so out the old came in with the new studs. then as i start to tighten up wap ...... one helicoil out GRRRR. so had a quick look to see that the helicoil had been put in but the hole behind it wasnt drilled in line so the stud went in and then hit the aly side and pushed the helicoil out  . so i checked the other internal stud to see that that one was identical
so after a short ride on the 125(45 miles) to get some shorter bolts to put in for now . i put liquid metal on the helicoil that pulled out hoping it would hold but liek hell has it . starts to tighten and just rips out!!!.
next problem . the left hand exhaust is on tight no wobbles. new gaskets (copper and papery flange one) all nice and tight and its blowing like a pig. i have put some copper wire behind the flange to pull them tight as the pipes where shaking when the flanges where tight. so what am i doing wrong??? gasket in the recess and flange gasket all nice nd tight and still blowing !!! should i get a few more paper flange gaskets to make sure its packed really tight ?
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Posted: Fri Jun 20, 2008 2:11 pm
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cb250g5 Mmm, Fully Synthetic! Joined: 03 Dec 2005 Total posts: 1067 |
I don't think more paper gaskets would help. Ideally you want less, I don't use any, I think they are an alternative to the large round copper gasket, not as well as.
What you are trying to achieve is making a gas tight seal between the engine and the circular part of the exhaust, via the big copper coloured gasket.
You don't want the oval bit to go tight against the engine, Ideally it should pull the pipe tight against the engine(via the gasket) whilst not touching anywhere. If it starts to touch the engine block, then it can't be pulling the pipe backwards properly.
If the oval bit gets bent, or the gaskets get thin etc, then this is when you should start to think about spacing things back a bit using copper wire or whatever, to give more space between the oval bit & the engine.
I hope this makes sense, easier to picture in my mind than write down.
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Posted: Fri Jun 20, 2008 2:25 pm
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WelshD1KSuburban Commuter Joined: 02 Jun 2008 Total posts: 57 Location: south wales |
so the oval bit behind the flange shouldn't touch the barrel ??? ok so that is all nice and tight . and it still leaks :S is there any thing i can put / add around the gasket to help make it air tight ?
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Posted: Fri Jun 20, 2008 2:30 pm
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WelshD1KSuburban Commuter Joined: 02 Jun 2008 Total posts: 57 Location: south wales |
any ideas on the helicoil side of things can it be re helicoiled?? however u do that :S lol
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Posted: Fri Jun 20, 2008 2:31 pm
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WelshD1KSuburban Commuter Joined: 02 Jun 2008 Total posts: 57 Location: south wales |
http://www.timesert.com/html/bigsert.html
can they be bought in the uk ???
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Posted: Fri Jun 20, 2008 2:50 pm
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Demondrew Find me a Road! Joined: 10 Jul 2007 Total posts: 18 Location: Chepstow |
Hi
Did the same thing a couple of months ago. Stripped the top end down and had the barrel re helicoiled. The original repair had obviously involved welding some material onto the barrel where the mounting flange had become damaged and then it was helicoiled so anything is possible.
Had it done in Bristol and it cost about £30 I think.
Cheers
Drew
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Posted: Fri Jun 20, 2008 2:55 pm
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barryfzr Daily Burner Joined: 04 Dec 2005 Total posts: 230 Location: Wales Baaaaaaa |
Wurth used to sell timesert kits here... but they're pricey - £70 ish 3 years ago (or I got ripped off)
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Posted: Fri Jun 20, 2008 3:58 pm
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WelshD1KSuburban Commuter Joined: 02 Jun 2008 Total posts: 57 Location: south wales |
oh well looks like barrels of over the weekend and down to my mates to weld and retap a lot cheaper ( few cans of beer) and ill get all 4 done at the same time get rid of them silly helicoil crap
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Posted: Fri Jun 20, 2008 4:37 pm
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NickIrons Powerband Master Location: Bienne Switzerland |
| WelshD1K wrote: |
| get rid of them silly helicoil crap |
ATB with the repair mate, but it sounds like the helicoil was not
put in correctly from the start. A good sized drilled hole and then
tapped for the helicoil, all nice and square, will be as good as it
ever was in the origional ally.
Helicoils get a bad rep, but most of the time this comes from 'em
being badly fitted in the first place.
May pay you to get yours done in a machine shop, get the hole
bored out and have an insert fitted...
ATB.
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Posted: Sat Jun 21, 2008 2:08 am
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Drewski Ace of Spades Joined: 29 Apr 2006 Total posts: 4934 Location: The Bunker,Cambridge, UK |
Permatek copper silicon sealant seems to do a good job closing up those last few leaks on the pipes. Have you had a good look at the recess for any burred metal or deformaties?
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Posted: Sat Jun 21, 2008 9:55 am
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