Leaking Valves


29 replies to this topic
  • FinchFan194

Posted September 03, 2012 - 06:28 PM

#1

Well my head is jacked!
I tore down the bike to do a top end and did the solvent test on my intake and exhaust ports, I have one valve leaking on each side.
Anyone have an idea what this costs to fix?

  • grayracer513

Posted September 04, 2012 - 06:12 AM

#2

Leaking how much?

  • FinchFan194

Posted September 04, 2012 - 06:14 AM

#3

Just slightly seeping out solvent...could they just be dirty?

  • grayracer513

Posted September 04, 2012 - 06:25 AM

#4

Slightly seeping is pretty normal for used valves. Give the top of the valve stem of each of the leakers a tap with a punch to bounce them off their seats a time or two (don't get carried away). A lot of times it's just carbon. Either way, it's not a big deal.

  • FinchFan194

Posted September 04, 2012 - 06:42 AM

#5

Ok, I will check it out! Thanks Gray I could kiss you right now! :lol:

PS, is there any concern of braking a valve?

  • FinchFan194

Posted September 04, 2012 - 06:46 AM

#6

Or any concern of a major failure?

  • grayracer513

Posted September 04, 2012 - 06:48 AM

#7

Ok, I will check it out! Thanks Gray I could kiss you right now! :lol:


Ew....

$5 says you won't do it.

PS, is there any concern of braking a valve?


"Breaking", and no, not because it seeps a little. :thumbsup:

  • FinchFan194

Posted September 04, 2012 - 07:00 AM

#8

Darn spell check!

...I said I "could" kiss you not that I would!

Thanks again!

  • FinchFan194

Posted September 04, 2012 - 07:04 AM

#9

One more detail...
So the exhaust valve was barely seeping by, but the intake was still seeping, but seeping much more. Still the same conclusion?

  • grayracer513

Posted September 04, 2012 - 09:18 AM

#10

More than a drop per second?

"Braking" wasn't misspelled, BTW. ;)

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  • FinchFan194

Posted September 04, 2012 - 10:00 AM

#11

About a drop.

  • FinchFan194

Posted September 04, 2012 - 10:03 AM

#12

It is not pouring out though...

  • grayracer513

Posted September 04, 2012 - 03:14 PM

#13

If it was steel, I'd suggest lapping it, but since it isn't, don't.

You might try removing that valve and clearing the carbon away from the seat and valve face. If it looks worn, get a new one and have the seat refinished.

You could also just run it. It's up to you.

  • FinchFan194

Posted September 04, 2012 - 03:48 PM

#14

Success!!!!
Gray, I just cleaned it up the best I could with Seafoam and tapped the top of the valves as you suggested and guess what?

NO LEAKDOWN!

  • FinchFan194

Posted September 04, 2012 - 08:09 PM

#15

Well some good news then some bad...cylinder has a score in it so I am gonna have to replace that. Still a LOT cheaper than doing the head, yet still a bummer.

  • FinchFan194

Posted September 04, 2012 - 08:36 PM

#16

Gray what should I use for the assembly lube? My local Napa guy tried to tell me Amsoil is the same thing as molybdenum or however you spell it!
Also what do you suggest for removing carbon from the head?

Edited by FinchFan394, September 04, 2012 - 09:38 PM.


  • grayracer513

Posted September 05, 2012 - 07:24 AM

#17

Soaking the head overnight with WD-40 works well to loosen carbon. Most of it will come right off.

Use your normal favorite engine oil for assembly and break in. The cylinder should be oiled for piston and ring assembly, but don't overdo it. Don't build it dry, either. Wipe a light film of oil onto the bore and piston/rings and assemble it.

Moly assembly lube can be used sparingly on the cam lobes if you want, but engine oil works fine.

  • FinchFan194

Posted September 05, 2012 - 04:01 PM

#18

Brother Gray, the WD has been hard at it for 6 hours and not really made a dent...time to have it tanked at a machine shop?

  • Charlie755

Posted September 05, 2012 - 06:30 PM

#19

Brother Gray, the WD has been hard at it for 6 hours and not really made a dent...time to have it tanked at a machine shop?


First off dont buy a new cylinder send it to Millinium Technologys in WI. They can replate the cylinder for less than what a new one costs and the plating they do will last a lot longer. No disrepect meant to Grayracer but every engine builder I know (including myself) seats the rings in the cylinder dry. If you are not confident in doing it that way then at least use non synthetic oil for break in. On getting the carbon off I use contact cleaner. Its takes a little bit of scrubbing with a small wire brush but I can usually get the combustion chamber looking almost brand new.

Where at in Washington BTW?

Edited by Charlie755, September 05, 2012 - 06:30 PM.


  • FinchFan194

Posted September 05, 2012 - 07:21 PM

#20

First off dont buy a new cylinder send it to Millinium Technologys in WI. They can replate the cylinder for less than what a new one costs and the plating they do will last a lot longer. No disrepect meant to Grayracer but every engine builder I know (including myself) seats the rings in the cylinder dry. If you are not confident in doing it that way then at least use non synthetic oil for break in. On getting the carbon off I use contact cleaner. Its takes a little bit of scrubbing with a small wire brush but I can usually get the combustion chamber looking almost brand new.

Where at in Washington BTW?

Thanks for the cylinder advice Charlie, but I have a race to get to on Sunday and time is of the essence! Combustion chamber is about 99% clean it is the valves and inner working of the head that is filthy with carbon.
I live right outside of Oly. You?





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