School me on compression releases
Club Member
Joined: Dec 2007
Posts: 4,192
Likes: 168
From: Knoxville, Tn
Compression Releases
If your compression stays stock, there is no need to put releases in the heads. The stock TC88 heads have to be drilled for them anyway. It will just make the starter last longer if you raise the compression a bit. If you go with high compression pistons and heads, your bike may not want to start without the releases.
Road Warrior
Joined: Jun 2008
Posts: 1,428
Likes: 0
From: Rescue, VA
Slightly off topic: when I was in the Navy doing ASW stuff, the base I was at (NAF Warminster, PA) had an old Super-Constellation full of testbed equipment and different electronics projects. To power that plane on the ground they had this huge power unit called a RY-400. Huge diesel engine it, big AC generator, and big selenium diodes to convert AC to DC. To start it, it had a compression release handle and a small reservoir with naptha in it. First you primed the engine with naptha, then started to turn over the engine to a set RPM, then slam the compression closed. usually you got a big fireball out the exhaust. You didn't start this parked under the wing...heheheheh
Ultimate HDF Member
Joined: Mar 2012
Posts: 6,129
Likes: 143
From: Santa Cruz
Why would ya want to keep stock compression??? Not really much good doing head work because any cam that will work with that low compression won't spin high enough to use bigger ports/valves??
Road Master
Joined: Mar 2010
Posts: 934
Likes: 54
From: SE Wisconsin
The Automatic compression releases are to relieve pressure when starting so you don't need a truck battery to start it.
They are basically small relief vales, they need to energized to open, they controlled by the ECM, the preset is for 2 revolutions at start up. Then they close.
They are basically small relief vales, they need to energized to open, they controlled by the ECM, the preset is for 2 revolutions at start up. Then they close.
Any engine will work better with the heads ported, you don't need a cam upgrade to benefit from porting. The problem with compression is it makes heat and none of us like that so if you can be happy with a stock compression you'll have a cooler running engine. If you have your heads off, drill them for releases and plug the holes if you don't intend to use them now, porting is a given if your going to tear into it. Depending of the cam you choose with the 95 build you may not need releases.
Ultimate HDF Member
Joined: Mar 2012
Posts: 6,129
Likes: 143
From: Santa Cruz
Any engine will work better with the heads ported, you don't need a cam upgrade to benefit from porting. The problem with compression is it makes heat and none of us like that so if you can be happy with a stock compression you'll have a cooler running engine. If you have your heads off, drill them for releases and plug the holes if you don't intend to use them now, porting is a given if your going to tear into it. Depending of the cam you choose with the 95 build you may not need releases.
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Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
If you plan on having your heads ported then talk to the shop about the need for releases, also easy start cams. If the engine performance you end up with puts your starter under undue stress you will want to give it an easier time. Been there......
Elite HDF Member
Joined: Dec 2010
Posts: 4,229
Likes: 10
From: Oklahoma
Little trivial thread drift. A long, long time ago I had a 2 stroke, 50 cc Sears Moped and it had a factory compression release. It was operated with a little thumb lever. I never figured out its purpose.
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