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Intake Valve Seals? What are these things?!? #767504
03/08/19 2:39 am
03/08/19 2:39 am
Joined: Jan 2019
Posts: 1
Ottawa, Ontario, Canada
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prmatzinger Offline OP
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prmatzinger  Offline OP
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Joined: Jan 2019
Posts: 1
Ottawa, Ontario, Canada
Hello everyone,

I found these rubber "boots" on the intake valve seats when I took the head apart. I am working on a 1976 Bonneville 750. Does anybody know what these things are? Why are they only on the intake?

A couple quick searches I did mentioned that they are valve seals. Are they harmless to leave inside? I'm not sure if those are from the factory or from some dude wrenching on it in the past.

Thanks for your help. Appreciate it smile

[img]https://lh3.googleusercontent.com/b...Xgm4YYgz12LOJDmhXe5ebn5oA=w1198-h1596-no[/img]

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Re: Intake Valve Seals? What are these things?!? [Re: prmatzinger] #767517
03/08/19 8:06 am
03/08/19 8:06 am
Joined: Aug 2001
Posts: 7,840
scotland
triton thrasher Online content
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triton thrasher  Online Content
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Joined: Aug 2001
Posts: 7,840
scotland
Can’t see the picture, but valve stem seals go on the top of the valve guide.

People say they don’t do any harm.


Amateur Loctite enthusiast.
Re: Intake Valve Seals? What are these things?!? [Re: prmatzinger] #767521
03/08/19 9:47 am
03/08/19 9:47 am
Joined: Dec 2004
Posts: 9,963
Scotland
kommando Online content
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kommando  Online Content
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Joined: Dec 2004
Posts: 9,963
Scotland
Fitted as std to Commando's to reduce oil consumption, only need to be fitted on inlets as the inlet sucks, not needed for exhaust as it blows.

Picture url is not right hence its a no show.

Re: Intake Valve Seals? What are these things?!? [Re: prmatzinger] #767524
03/08/19 11:45 am
03/08/19 11:45 am
Joined: Aug 2001
Posts: 7,840
scotland
triton thrasher Online content
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triton thrasher  Online Content
BritBike Forum member

Joined: Aug 2001
Posts: 7,840
scotland
They’ve been known to crumble from heat, on the exhaust side of old bikes.


Amateur Loctite enthusiast.
Re: Intake Valve Seals? What are these things?!? [Re: prmatzinger] #767539
03/08/19 2:41 pm
03/08/19 2:41 pm
Joined: Feb 2008
Posts: 4,866
New Jersey USA
Tridentman Offline

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Tridentman  Offline

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Joined: Feb 2008
Posts: 4,866
New Jersey USA
Certainly not a factory fitment.
Fitted on inlets only for reasons as per Kommando.
Some people swear by them--others swear at them.
Sometimes fitted in an attempt to "cure" oil leakage down the valve guide giving rise to exhaust smoking.
HTH

Re: Intake Valve Seals? What are these things?!? [Re: prmatzinger] #767551
03/08/19 4:43 pm
03/08/19 4:43 pm
Joined: May 2005
Posts: 3,870
ohio
shel Offline
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shel  Offline
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Joined: May 2005
Posts: 3,870
ohio
It's a pretty popular mod for the triples, never heard doing to a twin though.


When given the choice between two evils I picked the one I haven't tried before
Re: Intake Valve Seals? What are these things?!? [Re: prmatzinger] #767554
03/08/19 5:05 pm
03/08/19 5:05 pm
Joined: Jan 2012
Posts: 497
Western NY
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Pete Suchawreck Offline
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Pete Suchawreck  Offline
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Joined: Jan 2012
Posts: 497
Western NY
Amazed me when I tore apart a Triumph for the first time-no seals! Modern 4 strokes have them on intake and exhaust valves


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