I'm not happy is an understatement.

A place to discuss matters related to Honda Helix scooters.

I'm not happy is an understatement.

Postby Brianmckewen » Sun Sep 02, 2018 6:10 am

Replaced my head gasket and when I put antifreeze back in it leaked out at the new head gasket. A lot. I torqued it down the first time. I tightened it a little more and it still leaked out. Gasket I took off was all fiber, no metal in it. The new one I put back on was all metal, no paper that I could tell. Should I have put some kind of silicone sealant on the top and bottom of the new gasket when I put it on? I cleaned the contact surfaces to the gasket on the engine very well. You should be impressed that I did not use any profanity in this post. I am. Any suggestions would be appreciated. Thank you gang. Brian.
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Re: I'm not happy is an understatement.

Postby zozman » Sun Sep 02, 2018 3:54 pm

The service manual (6-12) says nothing about using shellac or any sealer on the head gasket.

I put head gaskets on dry and torque the head. After the engine is at operating temperture, I re-torque the head and I havent had any problems afterward.

The oldtimers suggest coating the new gasket with oil then install. Most of us racers use Permatex Indian Head gasket sealer.

One of my friends uses neversieze compound on the gasket so it moves into place and is easy to remove later.

The silicone sealer is messy and is recommended if the head surface is rough.

Take your choice here.

zoz
87 & 98 Helix
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Re: I'm not happy is an understatement.

Postby zozman » Sun Sep 02, 2018 4:10 pm

Brianmckewen wrote:Replaced my head gasket and when I put antifreeze back in it leaked out at the new head gasket. A lot. I torqued it down the first time. I tightened it a little more and it still leaked out. Gasket I took off was all fiber, no metal in it. The new one I put back on was all metal, no paper that I could tell.... Brian.


Some more suggestions:

Did you set the head on the engine and rock it to see if it did not move indicating a flat mating?

Did you use an original Honda gasket 12245-KS4-691 $26.60?

Was there an overheated condition on the bike engine which required you to replace the head gasket?

What year is your scooter and the mileage on it?

zoz
87 & 98 Helix
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Re: I'm not happy is an understatement.

Postby zozman » Sun Sep 02, 2018 4:31 pm

I spoke with my friend Mike who has been in the small engine repair business since 1968 about your situation. He said if the mating of the engine cylinder and the head was true, then you didn't need any gasket sealing material.


zoz
87 & 98 Helix
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Re: I'm not happy is an understatement.

Postby Brianmckewen » Mon Sep 03, 2018 5:34 am

Thank you Zozman but you have been helping an idiot. The gasket material I so carefully removed from the top of the cylinder head was actually the metal sandwiched between the paper on the gasket. When I placed the new gasket on top of this of course it leaked. I removed both gaskets, cleaned the real cylinder head again and sprayed permatex copper head gasket sealer on the new metal embossed gasket just to be safe and have just installed it with no leaks. This is how we learn. I will finish buttoning it all up together today and report back on how it went. Brian.
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Re: I'm not happy is an understatement.

Postby Brianmckewen » Fri Sep 14, 2018 2:02 pm

Got a new head gasket in the mail today. It says not to use it if "A" is on the side of the head. Mine has an "H-A" on it. I don't know why it would not work but wondering of anyone here knows. It is a three piece, all metal head gasket, not a single embossed one like the last time. It is OEM, but so was the last one, which was a single piece of metal. Why different OEM head gaskets? Thanks for any imput you guys can give me. Brian.
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Re: I'm not happy is an understatement.

Postby GrahamH » Sat Sep 15, 2018 3:57 am

There have been 4 head gaskets....all with part number12251-KS4-xxx
000 and 305 were superseded by 315
12251-KS4-315 is the thicker gasket and also has two extra holes with brass rings. These holes sit outside the cylinder head and do not appear to have a purpose with the Helix. My guess they had some use on the Hexagon scoot which used the same engine.

There is also 12251-KS4–691 which is thinner and does not have the extra holes.
On the CMSNL.com site there is a chart showing which gasket fits the ’A’ cylinder (691)
The cylinder is also referred to as ‘H’ so sounds OK with what you see.

My Helix is a UK 1992 which from the above should use 691 however I was not aware of the difference and fitted 315.....I did wonder what the extra holes were for but it works just fine.

My conclusion is you can use either gasket but by choice I would go for 315 (the slightly thicker one)

Hope this helps......GrahamH
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Re: I'm not happy is an understatement.

Postby Brianmckewen » Sat Sep 15, 2018 6:18 am

Thank you. Yes. I am going to use the thicker one. I assume the brass rings only purpose is to hold the assembly together and are on the outside so as not to interfere with the sealing of the cylinder head. Will report back on how it all works out. Brian.
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