Head Gasket Orientation which side? - Honda Rebel Forum
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post #1 of 6 Old 02-02-2020, 02:13 AM Thread Starter
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Join Date: Dec 2016
Location: Montana
Posts: 40
Head Gasket Orientation which side?

Trying to get my 2001 Honda Rebel 250 engine back together after replacing bent valves. My replacement head to cylinder gasket is OEM Honda #12251-KBG-671. It can be installed either side but it really appears that the two sides have different characteristics which makes me thing there is a right way and wrong way to install it. On of the sides has a definite impression throughout. Does anyone know how to explain to me which way I should install this. Pretty hard to see the impression in the photo. The first picture with my hand visible I would describe as having a small raised section right near the cylinder wall. The 3rd photo is the opposite side and there is clearly and slight depression on the section near the cylinder wall. Best way I can explain it if it even matters. Feels like a dumb question but I just want to get this thing back together without any more trouble. Lining up the cam gear timing marks have been giving me all kinds of trouble. Finally found a thread that I think explains how to get the marks to line up parallel with the cam holder. Going to give it a shot tomorrow if someone can get me straight on this gasket issue. Thanks.
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post #2 of 6 Unread 02-02-2020, 03:11 PM
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I've never done this, so keep that in mind. In your gasket picture above, you'll see two holes on one side of the gasket that aren't present on the opposite side. There are probably two passages in the engine that these are designed to fit over. Turn it so the gasket doesn't block those openings and it should be aligned properly.

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post #3 of 6 Unread Yesterday, 12:04 AM
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That actually looks like a base gasket for the cylinder to lower cases and not the head gasket for the cylinders to head seal gasket. It should be a metal fibre covered gasket with metal fire rings around the barrel piston holes if it is a head gasket. I think you have the wrong gasket there and should not use it as a head gasket if it is actually a base gasket.

The fire rings on any Honda headgasket should have two different widths on each side of the gasket with the wider section face the head and the thinner side of the fire rings facing the barrels. There is a difference when you look at both sides. The fire rings are the round metal rings that encircle the piston holes in your barrels and add protection to the head gasket around the combustion chamber area.

Someone else pondered this same question it seems recently too.

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post #4 of 6 Unread Today, 01:44 PM
Join Date: Nov 2019
Posts: 34
Those two cut outs are a U and P. You are looking at the bottom of the gasket in the pictures (cylinder side). This is per the instructions that came with the head gasket i just installed last week on my 87 rebel.
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1987 Rebel 250
2001 Rebel 250
2007 V Star 1100
2019 DRZ400S
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post #5 of 6 Unread Today, 01:54 PM
Join Date: Nov 2019
Posts: 34
You can see in the picture my 05 head with the UP still visible from when the gasket was removed. Of course we are looking at it from "under", so it is upside down...
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1987 Rebel 250
2001 Rebel 250
2007 V Star 1100
2019 DRZ400S
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post #6 of 6 Unread Today, 02:14 PM
Join Date: Nov 2019
Posts: 34
I would also like to add that it is the correct head gasket. Honda made several different versions. Some were just copper, but leaked. Yours has the metal rings under the black outer coating which is actually a mostly cured adhesive. If you look closely, the gasket has three layers. Make sure you torque all the bolts to spec, including the exhaust stud nuts, otherwise bad things can happen, like snapped studs.

1987 Rebel 250
2001 Rebel 250
2007 V Star 1100
2019 DRZ400S
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