Does anyone lap valves anymore?
Thread Starter
Racer
Joined: May 2004
Posts: 288
Likes: 0
From: Tigard OR
Does anyone lap valves anymore?
I remember doing this years ago, is it still required today with the higher quality heads and valves that are available? what are the pro's and con's of doing this?
Burning Brakes
Joined: Jan 2007
Posts: 1,057
Likes: 4
From: Concord Calif
A big yes on this and my shop turns out about five sets of heads a day and all are lapped after grinding with an interference angle of 1 degree
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
I do it on every motorcycle motor I build...I have gotten heads back from the best head machinest in the country and do a leak test and had them leak....A couple hours with 2 stages of lapping(medium then fine compounds) they seal up tight as a drum and I usually end up with less then 2% leak down.....This is on a 1300cc that makes 430+hp....
I would HOPE that true engine builders/head builders are still lapping em.
I would HOPE that true engine builders/head builders are still lapping em.
Safety Car
Joined: Oct 1999
Posts: 4,101
Likes: 10
From: NorCal
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 98
From: Ontario
I do it on every motorcycle motor I build...I have gotten heads back from the best head machinest in the country and do a leak test and had them leak....A couple hours with 2 stages of lapping(medium then fine compounds) they seal up tight as a drum and I usually end up with less then 2% leak down.....This is on a 1300cc that makes 430+hp....
I would HOPE that true engine builders/head builders are still lapping em.
I would HOPE that true engine builders/head builders are still lapping em.
Racer
Joined: Sep 2009
Posts: 459
Likes: 0
From: Belair Md
just had my heads done ,i had 175 compression before. now i have 150 to 170 all over the place.when i asked the machine shop why?????? i was told because he did not lap in the valves.that he dosent do it on street machines because they seat themselves after driving . i would have rather paid the difference and had it right from the jump!
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Burning Brakes
Joined: Feb 2009
Posts: 780
Likes: 1
From: Shelby NC
I remember that suction cup, hand-driven wooden handle tool for my motorcyles. Pretty crude but darn they sure got things down to no leakage. The years do fly by.[/QUOTE]
I am glad that is one thing my Dad taught me. It can make your hands pretty tender after a while but the results are priceless. Kinda goes back to that thing about new blubs that don't burn and new spark plugs that don't fire. If you do it then you know and the guess work is gone! And you bet your b--t the years fly by!!
I am glad that is one thing my Dad taught me. It can make your hands pretty tender after a while but the results are priceless. Kinda goes back to that thing about new blubs that don't burn and new spark plugs that don't fire. If you do it then you know and the guess work is gone! And you bet your b--t the years fly by!!
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
Yep, thats still how I do it...They do make a tool with a suction cup on one end and a little hand crank gearbox assy on the other end....just turn the crank and the shaft spins back and forth to lap the valves. I still just use the old hand method with the wooden handle suction cup. Very time consuming but it works well. You have to lap the valves to get the seats to seal up 100% in my opinion.
Wrencher,
These little 1300cc engines are in Suzuki Hayabusa sport bikes, we have them fully built with forged goodies, studs etc and mine has a t3/T4 turbo on it. 28lbs of boost makes 435rwhp. I have only actually rode it with about 18lbs(around 340-350rwhp).... I ran 225mph on it at the Texas Mile back in March and this past friday night I went 8.97@166mph in the 1/4 with only 14lbs of boost and a crappy front half...it should go 8.60s once I learn to ride it...thats BEFORE I turn the boost up....
Last edited by ajrothm; Oct 26, 2009 at 09:32 AM.
