Honda 450 Cylinder O-rings - Are they necessary?

[jchek779]

I'm trying to finish the engine rebuild of my 69 CL450. The o-rings that are fitted around the base of the cylinder sleeves don't seem to have room to displace when compressed between the bottom of the cylinders and the top of the crankcase where the base gasket is. Typically there is a groove or generous chamfer to allow room for o-ring compression. I really don't like the limited compression of the base gasket and subsequent "lift-off" of the cylinders because of the restriction provided by the o-rings.

I think the o-rings are in place to prevent oil leaching through the cylinder lining. The service manual states they prevent gas leaks. I don't want to compromise my build by using these o-rings - they came in the Athena "complete" gasket set that hasn't exactly been that exact in other places.

Does anyone else have any experience with this? Any advice?

 

[cqyqte]

As I recall during my engine rebuild I noticed that there is a chamfer at the point where the bottom of the cylinder sleeve meets the cylinder head, which allows for the compression of the "O" ring into that void when the head is torqued down. Correct me if I am wrong. Did you remove the cylinder sleeves and have the lower deck machined? If so that may account for your issue.

In any case I would not want to leave out any component, which the factory deemed necessary. :-[ It would suck to have to open it back up to put them in place after you find adverse side affects without them.

 

[mydlyfkryzis]

Check the factory service manual and see, or at least a parts microfiche. Maybe that year didn't use them, or maybe you have a wrong part.

http://www.houseofhondaparts.com/fiche_select2.asp?category=Motorcycles&make=Honda&year=1969&fveh=132828 shows no o-ring in the microfiche for your model. Hopefully the gasket is the correct one too.




Sent from planet Earth using mysterious electronic devices and Tapatalk

 

[cqyqte]

Sorry to disagree, but my source clearly shows "O"rings for that model and year '69 CL450 part #7
http://www.sturgessonline.com/fiche_section_detail.asp?section=2559520&category=Motorcycles&make=Honda&year=1969&fveh=132828

 

[jchek779]

False alarm guys - Thanks for the quick feedback.

When assembling the cylinders on the crankcase, the o-rings were holding the cyls proud by about 1/8". I put the head on and torqued the acorn nuts down to about 15lb-ft and there was still the slightest play felt in the base gasket. I was initially hesitant because I didn't want to waste a new head gasket. This morning, i torqued the nuts to spec and all is good.

Thanks again.

 

[Rude Boy]

So I'm in the process of rebuilding a Honda cm450 and have run into the same problem as well.

jchek could you clarify a bit more on the process of those o-rings? Were you replacing them with new ones? That's what I'm doing.
I've cut a new gasket and it isn't quite flush to the cylinders. I'm wondering if that would keep the o-rings from fully seating.

Did you use a factory gasket?

 

[jchek779]

Rude,
The o rings around the lower part of the cylinders were causing the cylinders to stand proud of the crank case. I was initially alarmed because I couldn't get the cylinders all the way down by hand. I tightened the cylinder head nuts in a number of sequences to draw down the cylinders against the force off the o rings. Then life was good.