Author Topic: Source for thicker 550 head oil o-rings? (Read 1070 times)

middletons · « **on:** January 19, 2021, 06:00:16 am »

Newly assembled 550 top end leaks at the oil galleries on each side of the head gasket. I have read this is because of improperly sized o-rings (or thicker head gaskets). Is there a source for thicker versions?

bryanj · « **Reply #1 on:** January 19, 2021, 03:49:46 pm »

I just googled the size i wanted and found a supplier but ask Hondaman he may have some. If you have heat cycled the head gasket you will need another new one and are you certain its the O rings because the dont normaly leak immediately and there are other places that leak

jonda500 · « **Reply #2 on:** January 19, 2021, 05:25:03 pm »

If the head gasket comes off clean and like me you're not made of money, you can re-use it. I did thousands of kilometres ago and still have no leaks from the head or base gasket.
John

craz1 · « **Reply #3 on:** January 19, 2021, 07:07:45 pm »

So what would the correct size be. What brand gasket are you using.

DaveBarbier · « **Reply #4 on:** January 19, 2021, 11:02:34 pm »

Did you use OEM? What head gasket did you use? And I agree with really being sure it’s the o-rings you think. Oil runs down everywhere and can make it look like it’s leaking from where it’s not.

dave500 · « **Reply #5 on:** January 19, 2021, 11:20:45 pm »

ive reused head gaskets on these twice over with no problem if they come off intact,a decent diesel pump and injector service place will have the rings you need for cheap if you take a sample or know the size.

middletons · « **Reply #6 on:** January 20, 2021, 06:18:27 am »

As for if I’m sure it’s the o rings, the leak is at each end of head, so it seems like it’s gotta be the o rings right?

The head gasket I’m using is whatever came with the kit from 4into1. They sell a stand-alone gasket that is NE brand, so I’m guessing that’s what’s in the kit.

I don’t plan on reusing the head gasket.

Stock size is 4.9 x 2.5mm. I’ve found some places that sell metric o rings, the problem is that I don’t know how much larger to get. .5mm thicker, 1mm?

DaveBarbier · « **Reply #7 on:** January 20, 2021, 06:44:19 am »

The issue is the o-rings are sized correctly from Honda based on the thickness of the Honda head gasket. Some aftermarket head gaskets might be thicker so you’d have to calculate or trial and error what o-rings will work.

If I were you, I’d buy an OEM head gasket and use the Honda o-rings. Or at least the correctly sized o-rings in Buna N (nitrile). That will ensure a good seal that will likely last for another 30-40 years.

DaveBarbier · « **Reply #8 on:** January 20, 2021, 06:49:57 am »

Head gasket part number is 12251-374-306
O-ring part number is 91301-426-010

O-rings are available and I think the head gasket is too. Might be a little harder to source though for a good price.

I say do it once right and move on to enjoying the bike. Head gasket and o-rings go on dry by the way. No sealant.

middletons · « **Reply #9 on:** January 20, 2021, 08:03:32 am »

yep, I'd rather do it right once. I didn't realize the gasket/O-ring fitment was a known issue when I did the top end.

bryanj · « **Reply #10 on:** January 20, 2021, 08:05:43 am »

Nope, even the NOS Honda gasket are thicker since asbestos was removed. If you look up the O ring part number it will tell you the size and you need some 0.2mm thicker

middletons · « **Reply #11 on:** January 20, 2021, 08:16:40 am »

hmm. well i guess I'll continue trying to find slightly thicker O-rings and hope it seals with an aftermarket head gasket. I'd hate to do all that work AGAIN and have it still leak.

craz1 · « **Reply #12 on:** January 20, 2021, 08:40:12 am »

I will be using a Versa gasket kit so I will assume they supplied the proper ring with there gasket. I will double check. In general I have never had a problem with Versa kit, that being said this is my first CB550.

bryanj · « **Reply #13 on:** January 20, 2021, 09:16:18 am »

No they dont, none of them supply an oversize O ring. They supply everything as to Honda specs except the head gasket which without asbestos would be too fragile if original thickness

craz1 · « **Reply #14 on:** January 20, 2021, 12:05:33 pm »

What size bring have people been using with the Versa gasket.

middletons · « **Reply #15 on:** January 20, 2021, 12:06:14 pm »

I assume you mean a Vesrah gasket kit.

dave500 · « **Reply #16 on:** January 20, 2021, 11:35:57 pm »

be sure your leak isnt from the cam end cap o rings or its holding bracket washers,lotta wind turbulence around there might make it hard to trck the exact location down,make sure the bracket has no burrs around its bolt hole,use copper top and bottom on the bolt.

DaveBarbier · « **Reply #17 on:** January 20, 2021, 11:55:48 pm »

Quote from: middletons on January 20, 2021, 06:18:27 am

As for if I’m sure it’s the o rings, the leak is at each end of head, so it seems like it’s gotta be the o rings right?

As long as there’s no oil on the fins above the head gasket. It’s a common thing to be tricked where oil leaks are coming from. Some people clean the motor and sprinkle baby powder around which will more easily show the trail of oil when it starts leaking. But as long as you’re totally sure, move forward with the fix.

middletons · « **Reply #18 on:** January 21, 2021, 07:48:30 am »

Quote from: dave500 on January 20, 2021, 11:35:57 pm

be sure your leak isnt from the cam end cap o rings or its holding bracket washers,lotta wind turbulence around there might make it hard to trck the exact location down,make sure the bracket has no burrs around its bolt hole,use copper top and bottom on the bolt.

thanks for the suggestion. I checked that location when I first saw the leak, you can clearly see the oil coming from between the head and jug on the each end.

middletons · « **Reply #19 on:** January 21, 2021, 08:21:08 am »

Quote from: bryanj on January 20, 2021, 08:05:43 am

Nope, even the NOS Honda gasket are thicker since asbestos was removed. If you look up the O ring part number it will tell you the size and you need some 0.2mm thicker

thanks for that info.

dave500 · « **Reply #20 on:** January 22, 2021, 12:53:43 am »

also i like to lightly chamfer that oil feed hole in the head.

dusterdude · « **Reply #21 on:** January 22, 2021, 02:09:00 am »

If you still need o-rings,try oringsnmore in henrico va

Sent from my LM-X420 using Tapatalk

middletons · « **Reply #22 on:** January 22, 2021, 05:51:28 am »

Nice tips, thanks.

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Author Topic: Source for thicker 550 head oil o-rings? (Read 1070 times)