New exhaust rings - silicon sealant

[colink98]

my exhaust is making some noise again and i have ordered a set of new rings and studs (as the studs where a mess).

i recall giving everything a good clean last time around and was not overly impressed with the exhaust headers (if that's the right name).

is it good, bad or ugly to run a smear of silicon over the new exhaust rings to aid with a decent seal ?

i have read its OK to use silicon to seal other joins of the exhaust
I'm just not sure about so close to the engine.

Cheers
C.
____________________
PCX125 (stolen) - CBF600 (current)
Ride it like you stole it.
ride sensible and not like an idiot and you wont get 6 points in one week.

[chris-red]

I do not know but I wouldn't have thought silicone could handle the 800+ degree temps of an exhaust.
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[DrDonnyBrago]

I've used bathroom silicone around end cans and link pipes, might survive around a head-downpipe gasket but it shouldn't be required fi you are using nice new gaskets.

I've had better experiences with the copper ring gaskets over the fibre/aluminium versions.

[Rogerborg]

I've not tried using it at the head, but await stinkwheel's pronouncement with interest.
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[Baffler186]

Most high temp silicone I have seen is good up to 3 or 400 degrees C. I wouldn't have thought that is enough. Some people have used normal silicone on end cans etc but when I tried it on one of my old bikes it started to burn and turn into crisps within a couple of weeks. I would not do it myself unless you can find silicone that's resistant up to 8 million degrees and specifically deigned for the job.
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Current: 2009 SV650 S, 1990 Kawasaki GT550
Previous: 2009 CBF125, 1998 GSF600, 2004 FZ6 Fazer, 1978 CB400a Hondamatic

[Hawkeye1250FA]

Good gasket fitment and properly tightened bolts are sufficient 👍

No reason to mess it up with silicone that will burn and drop off within hours.

If your gaskets are shit - a touch of instant gasket around the OUTER edges before closing and tightening the bolts will help.

Silicon = no
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1993 RF400R - 2002 Bandit 1200 - 2012 1250 FA

[Rogerborg]

[MCN]

[stinkwheel]

I've used plumbers silicone on the header of my air coooled enfield. However hot that gets.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Hawkeye1250FA]

[stinkwheel]

It's not going to be 800 degrees anyway. Aluminium melts at 660 and that's what the engine, and the metal foil in composite exhaust washers are made of.

How hot is something in contact with the cylinder head of a liquid cooled bike actually going to get? I'd be very surprised if it's over 200.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Hawkeye1250FA]

[chris-red]

[stinkwheel]

[stevo as b4]

I wouldn't tune anything based solely on EGT readings. Its just another indicator tool when you have all singing equipment for monitoring and setting up engines.

They got by years ago without EGT sensors, and from just what I've read on two stroke tuning, EGT's vary with stuff like types of fuel, compression ratios, head design etc. Its easy to get into a minefield and then ignore basic principles IMO.

[-]

Holts have a bronze coloured silicone sealant which is good for pipe headers, is resistant to oil and can stand up to 350oC.

5990...

https://www.halfords.com/workshop-tools/garage-equipment/head-gasket-exhaust-repairs/loctite-5990-premium-silicone-copper-gasket-maker-sealant
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[Rogerborg]

[ThatDippyTwat]

Another vote for Loctite 5990. My total bodge-job exhaust uses it liberally. Used just after first bend and in a few places down to the endcan. Just Works.
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'98 VFR800 (touring) - '12 VFR800 Crosrunner (Commuting) - '01 KDX220 (Big Green Antisocial Machine)

[Hong Kong Phooey]

If the bike is EFI with modern emissions control systems make sure the sealant is o2/lambda safe.
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'81 CG125, '97 FZS600 : '99 CBR600F4, '09 KTM RC8

[colink98]

[MCN]