Complete engine gasket set
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Intermediate
Joined: Sep 2022
Posts: 31
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From: Washington
Road Master
Joined: Feb 2015
Posts: 1,040
Likes: 203
From: Susanville CA
By no means am I an expert but my understanding is the thinner gasket will raise compression slightly.
Club Member
Joined: Mar 2009
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From: Niles Canyon Ca.
Seasoned HDF Member
Joined: Mar 2021
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From: backwoods
NOr the one I bought this year that I recall. Box full leftover junk
Road Captain
Joined: Mar 2020
Posts: 654
Likes: 356
From: Sierra foothills
I used to use the James. 036 head gaskets back in the 90's. Little bump in compression was nice. Never any head gasket issues with them. Don't think MLS were available back then.
Last evo i did about 10 years ago i used cometic head and base gaskets and everything else including rocker boxes I used HD. But that bike had head work and cam
Last evo i did about 10 years ago i used cometic head and base gaskets and everything else including rocker boxes I used HD. But that bike had head work and cam
Seasoned HDF Member
Joined: Mar 2021
Posts: 18,252
Likes: 3,679
From: backwoods
I've had good luck finding old parts manuals cheap on eBay. Plus Ron's still has parts finder. Not sure if that will change with Harley cracking down on internet sales.
Make a list and bring it in. Tell them come back, ask to be labeled.
I do wonder if you are paying for convince. Engine kit is around $150. I usually reuse primary gasket
Make a list and bring it in. Tell them come back, ask to be labeled.
I do wonder if you are paying for convince. Engine kit is around $150. I usually reuse primary gasket
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Tourer
Joined: Jul 2014
Posts: 426
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From: Lake Wales, Fl
The compression bump is slight - It is to tighten up the squish for better turbulence & burn
Stellar HDF Member
Joined: Aug 2020
Posts: 3,177
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From: College Station, TX
When you remove the top end to replace gaskets, you need to check the studs to be sure none are coming lose. If they are, replace as needed.
When things are apart, you need to check the deck height of the pistons to determine if they are above or below the top of the cylinders to determine which head gaskets to use to achieve the proper squish band, which is the space between the top of the piston and the head at TDC. Ideally you want about .030-.035. It won't do much to raise compression, but it will help with flame travel and help to prevent detonation. If you want to raise compression, you will need to either change pistons or have the heads shaved about .060. I didn't see the mileage, but I'd also replace the rings and do a valve job and replace the stem seals while in there. If it were mine, I'd upgrade the cam and inner cam bearing too.
To check the deck height, clean the cylinder bases and case surfaces, and install the pistons and cylinders without rings or gaskets and lightly bolt the cylinders down. Rotate the engine until the piston for each cylinder is at the top and measure the distance above or below the top of the cylinder. Then add the cylinder base gasket thickness to the measurement to determine which head gasket to use to achieve the desired squish band. Once you have that information, if you know the cam in the engine, you can use BigBoyz calculator to determine static and corrected compression etc.
http://www.bigboyzheadporting.com/EVOComp.htm
Paul
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