Topic: Lapping compound?

[70CB750]

What lapping compound do you use on valves?  Just the regular Permatex:

http://www.motorcycle-superstore.com/22900/i/permatex-valve-grinding-compound?SiteID=Google_PLA988&WT.mc_ID=10012&esvt=0-GOUSC&esvadt=9-0-3886819-1&esvaid=30548&device=c&matchtype=&network=g&gclid=CJ3BhPze8LoCFU7xOgodIDsAhA

??

[Black 750K8]

I'm no expert and I'm sure they will chime in but I think of it like sandpaper there are different grits depending on how much it needs done. if you do it just after a valve job use the fine. You can get it at almost any auto parts store cheaper without shipping.

[Ace]

I've just lapped some valves in. Needed coarse grit to get some of the pitting out then finish off with fine grit.  Came in a double ended tube, coarse one end the other fine.  Valves lapped in fine and no leaks afterwards when tested with 5w oil. Third head I've done like this.

[skidooextreme]

Why would you test leaks with oil?  Use diesel or gas with the head upside down.  Air is tricky and will blow through the slightest small hole.  Liquid will show you problem areas faster and much more accurate

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[Xnavylfr]

SKID is correct!!  Use some thin liquid to check for valve leaks. The molecules in the oil bind together and if it is a small leak oil may not seep pass!!
Lapping compound usually is in 2 grits / coarse and fine. Be sure to use the hand lap method not a drill attached to the tappet end.


Xnavylfr(CHUCK)

[70CB750]

Hondaman talks about 5 weight oil in his book.  I used rubbing alcohol to leak test.

[skidooextreme]

Does he use this method with the engine altogether ?  I will agree if thats the case

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[dave500]

i use a hose chucked into reversible variable drill on the valve stem end,run it both directions,just dont spin the #$%* out of it.

[Vinhead1957]

Go to NAPA and pick up a tube!  Use a marker pen and make lines across the valve surface. While you are at Napa pick up a lapping tool. A double ended suction cup device.  Use the tool by hand.  By HAND only. Lap the valve until the mating surface connects all the lines. It is a fine process. Only to verify the seat and valve have a good mating surface. Ideally the line it makes is as wide as the seat surface.

[LesterPiglet]

The tool.


The paste.



I do it all by hand, I don't have a significant other.   

[70CB750]

Could we talk some numbers here.  Like Coarse compound to use is 80 and Fine compound for lapping valves is 200 grit?

Feeling in the dark here, what #s do you use?

[flybox1]

The Permatex tubes I purchased, had no numbers. 
It was either fine or coarse.   I have yet to use.

[iron_worker]

The set I bought from Canadian tire has 120 and 280.

http://www.canadiantire.ca/en/pdp/powerbuilt-valve-lapping-compound-0253201p.html#.Uo-c7NIw3G4

Whether it's any good or not ... I don't know. lol

IW

[70CB750]

Thanks, I found some Jeg's compound on ebay I will get when I finally push my blasted jeep through inspection; that's like never ending story.