evo head gaskets
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Stage I
Joined: Feb 2019
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From: vine grove ,kentucky
evo head gaskets
i have a 96 heritage had a blown head gasket when i got it ive put new mls head gaskets on it twice still blows head gaskets after about 20 miles . ive put new pistons rings cylinder studs and new cylinders have torqed the heads to 42 ft lbs still blows the head gaskets any ideas would be a grat help
Cruiser
Joined: May 2020
Posts: 230
Likes: 447
From: SW Florida
i have a 96 heritage had a blown head gasket when i got it ive put new mls head gaskets on it twice still blows head gaskets after about 20 miles . ive put new pistons rings cylinder studs and new cylinders have torqed the heads to 42 ft lbs still blows the head gaskets any ideas would be a grat help
Seasoned HDF Member
Joined: Apr 2011
Posts: 6,183
Likes: 2,131
From: W. Texas
New cylinders as in brand new ?
At minimum start cking sealing surfaces on the heads and cylinders
Blows a gasket in 20 something miles WOW
Oh Which head just for conversation?
Is it together or apart at this time ?
WP
At minimum start cking sealing surfaces on the heads and cylinders
Blows a gasket in 20 something miles WOW
Oh Which head just for conversation?
Is it together or apart at this time ?
WP
Seasoned HDF Member
Joined: Aug 2007
Posts: 8,195
Likes: 3,085
From: NW AR
Yeah, check for flat first. Also, are we SURE that things are still torquing down when you are turning? That is, the head bolt is not bottoming out on the stud? Stud in far enough?
Personally, I don't do the 42 ft lbs thing. I have had bad results with that. I do like the book says, however many INCH POUNDS, then 1/4 turn. I've never had a problem doing it that way.
Personally, I don't do the 42 ft lbs thing. I have had bad results with that. I do like the book says, however many INCH POUNDS, then 1/4 turn. I've never had a problem doing it that way.
HDF Community Team
Joined: Jan 2020
Posts: 1,434
Likes: 800
From: Colorado
I do the 42lb as the forth torquing and have not had a problem yet.
http://www.nightrider.com/biketech/h...rquevalues.htm
So if you are blowing head gaskets that fast, either head and cylinders are not flat to each other to allow head gasket to seal in the first place, studs are pulling up from case, your getting a false torque reading by craps in the threads/ head bolt bottoming out on top of studs, or you did not check squish (.030" +) and pistons are tagging bottom of head on top of stroke instead.
Note here, if you are going to use a lathe to remove the old base gasket, just remove the gasket and maybe a few thousands at most to square the bottom of the surface back up to the cylinder bore line. Going much more than this, will increase the compression, decrease the squish amount between the top of piston at TDC to bottom of head. As for squish, you can check it without the gaskets to start with, but measure the gaskets to add them back into the clearance amount before you bolt every thing thing down. And if you replaced the top end piston rod bushings, do this before you measure for squish in the first place. Final reaming of the bronze bushing can end up with the channel higher or lower than before, and need to take that into account.
http://www.nightrider.com/biketech/h...rquevalues.htm
So if you are blowing head gaskets that fast, either head and cylinders are not flat to each other to allow head gasket to seal in the first place, studs are pulling up from case, your getting a false torque reading by craps in the threads/ head bolt bottoming out on top of studs, or you did not check squish (.030" +) and pistons are tagging bottom of head on top of stroke instead.
Note here, if you are going to use a lathe to remove the old base gasket, just remove the gasket and maybe a few thousands at most to square the bottom of the surface back up to the cylinder bore line. Going much more than this, will increase the compression, decrease the squish amount between the top of piston at TDC to bottom of head. As for squish, you can check it without the gaskets to start with, but measure the gaskets to add them back into the clearance amount before you bolt every thing thing down. And if you replaced the top end piston rod bushings, do this before you measure for squish in the first place. Final reaming of the bronze bushing can end up with the channel higher or lower than before, and need to take that into account.
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