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xs650 > > High Performance Modifications > > Top End Work > > replacing valve seals


replacing valve seals
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Coupelx
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Joined: Dec 07, 2009
Posts: 4

PostPosted: December 15, 2009, 9:14 pm    Post subject: replacing valve seals

i am going to be pulling the head to replace the valve seals, clean up the ports and lap the valves. will this mean i need to replace the base gasket? im a 2 stroke guy so this 4 stroke small engine stuff is new to me.


also anyone ever tried running 2 base gaskets (or making a thicker one) instead of 2 head gaskets to lower the compression? seen this done in 2 strokes to move port timings around.
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benztech
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Joined: Sep 01, 2009
Posts: 62

PostPosted: December 15, 2009, 9:29 pm    Post subject: Re: replacing valve seals

the base gasket is very thin compared to the head gasket. I don't think adding 1 would really do anything. I just pulled the head on my motor and the jug got lifted so I f-it and just pulled it off. I think if you keep the seal intact you should be ok
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Srinath
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Joined: Sep 10, 2009
Posts: 343
Location: Charlotte NC

PostPosted: December 15, 2009, 9:38 pm    Post subject: Re: replacing valve seals

Yea more than likely you will disturn the base gasket seal, get oil in the gap and it will leak when you re fit it.
I would replace it anyway even if its not distrubed. There are bikes that the cyls are bolted to the case. Those are the ones you can skip it on.
Cool.
Srinath.
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xsjohn
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Joined: Jul 30, 2006
Posts: 5857
Location: North Carolina USSA

PostPosted: December 15, 2009, 10:03 pm    Post subject: Re: replacing valve seals

2 base gaskets I'm afraid would smash out and leak..........for lifting the barrels..now a custom copper or aluminum one would work (along withe 1 gasket) and they aren't very expensive to have made 35-40 bucks...(sorry to repeat the same ole bs as it was called) will cause a fresh break in.....lessening longivity...........if you remove it leave the pistons in the bore and pull the pins if you suspect the top end is ok....rocking pistons front to back...just a bit of movement means the clearances are probably ok ....a lot not good............in between you decide......

I would go for reusing the original base gasket if it was mine and have done that in the past many times with success.........

Learned a good trick to torque these with the long case bolts...use anti seize and bump the torque wrench to 35 lbs on final torque instead of a steady pull..........so the bolts don't just twist and spring back giving a funky reading..............and loosening.......and or not the same for all...

raising head means having to move cam also.........

xsjohn
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dpmphoto
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Joined: Apr 18, 2007
Posts: 485
Location: syracuse NY

PostPosted: December 15, 2009, 11:21 pm    Post subject: Re: replacing valve seals

I've heard about lowering the compression on the xs for better performance does anyone know the ballpark figures
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xsjohn
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Joined: Jul 30, 2006
Posts: 5857
Location: North Carolina USSA

PostPosted: December 15, 2009, 11:28 pm    Post subject: Re: replacing valve seals

Yea I have done a few.........gets rid of vibes and ratcheting and makes it run right.........you do loose a bit of HP....the bottom comes in sweet and not cranky at 2000 with the timing retarded ........it's not a performance mod.......just makes it run really sweet so you can enjoy the rides long or short.......lot..lot easier on everything too..........

Did mine at 60K and will never go back ....75.5k now......not a sound comes from the engine........finally.....tack needle dead still.....metalic clanking noises and you are loosing the game........ Laughing
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Srinath
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Joined: Sep 10, 2009
Posts: 343
Location: Charlotte NC

PostPosted: December 15, 2009, 11:44 pm    Post subject: Re: replacing valve seals

FWIW John ... On mine I was delicate as a mouse and still ended up tearing the base gasket.

On everything I do I actually am capable of doing work on the part I am working on only and not even touching the stuff that is near by ... like my crank, I pulled it apart without pressing the rod pins out ...

Anyway I was in the time of splitting my 82 motor still looking for what mau have made that crunk crunk noise when turning over. So I would have not broken a flower had it been inside the motor ...

Reminds me of my mechanic who when he found out I was hittiing somehting with my mallet ... the small 5lb one whihc was white in color to boot ... said in his heavy mexican accent ... "Oh a mallet ... why ?? you didn't hit it with a flower"
Then he went on ... "when you hit it with a flower, be careful you dont break the flower"

There is also one of the funniest stories I have ever said where he mistook green korean wasabi for guacamole ... Here is a hint, mexicans cannot eat wasabi ... and mistaking it for guacamole is certain recipie for a shock.

Cool.
Srinath.
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xsjohn
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Joined: Jul 30, 2006
Posts: 5857
Location: North Carolina USSA

PostPosted: December 16, 2009, 12:06 am    Post subject: Re: replacing valve seals

Base gasket............I meant if you don't lift the barrels......if you do it will sure tear it.............try the rocking of the torque wrench.........stopped leaks on mine a few times that way.........must be better for assembly on these long studs.......antiseize ...
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