Head Gasket Leak/Burning Oil

Joined
Aug 16, 2004
Messages
10
The head gasket on my 74 commando is leaking oil. The riding season is coming to a close here in the frigid northeast and I would like to finish the season before replacing gasket (considering going through entire motor, rather than just replacing gasket this winter). Assuming oil level is kept up to keep up with consumption, is there any risk of further damage that may result from running in this condition?
Secondly, can oil be sucked into combustion chamber from a leaky gasket or do I assume that burning oil (more pronounced on the side that also appears to be the leakiest) is the result of rings/valves. (haven't checked compression yet). Bike runs reasonable well despite the above described condition(s).
Any input is appreciated.
Thanks for the help -
 
Joined
Apr 7, 2004
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1,691
It's most likley that the oil your seeing is excaping around the push rod tube in the jug casting. If this is the case then just keeping up with the loss woun't hurt the engine. I have noted that this kind of leak is best kept at bay by getting the oil up to temp. before exceeding 4000 RPM. A good crank case breather with a check valve also helps alot. I would never take down for a rebuild a good motor over a leak. It may be that the little 5/16 studs have just lost thier grip in the casting and need stronger theads installed. A bit of Copper kote spray around the push rod tube on both sides of the gasket and three re-tourques of the head.. One long days work if you rush it. You may have a lot of good riding days left never know sorry if you miss em.
 
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Apr 7, 2004
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The first re tighting of the head is best done after one heat cycle. No need to drive the bike. just get it hot let it cool then re-tighten and re-lash the valves. second at 100 miles or so. after first good ride. thrid at around 5-700 miles just a recheck really.
 

L.A.B.

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I don't think it sounds too serious.

If any reasonable amount of oil was able get into the combustion chamber then you would have a smoke screen behind the bike, and the plug/s would probably oil up all the time.

Have you tried re-torquing the head down?
 
Joined
Aug 16, 2004
Messages
10
Thanks for the quick replies!
I ordered a 1/4 W socket and it expect it in the mail any time now.
Plan is to retorque and see if problem goes away. 2nd step is to remove head and replace gasket. Inspect top end while apart. Any additional input regarding what to expect is always appreciated.
Some times I worry to much I guess!
This forum is an incredible resource.
Rich
 
Joined
Sep 1, 2006
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3
Copper head gaskets nearly always leak , but are more resistant to blowing .
If your engine is wet sumping it will smoke on start up and give the impression that guides or rings may be to blame .But will run fine after the initial start up .
A compression check is the only way to find out .
 
Joined
Aug 16, 2004
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10
OK the head bolt accessability is a bit tight! The bolt under the intake I can't see how a socket could fit and it seems an open end only gives me only a tiny bit of bite. Am I missing something here or is there a special wrench to get at these and still be able to get a reasonable torque reading. Any pointers are appreciated.
Thanks
Rich
 
Joined
Aug 11, 2006
Messages
93
Hi Rich-
You need to take the box end (ring spanner) section of the wrench over to the grinder and remove some of the material on the end and sides until it fits. Daunting prospect, but you'll have a specialized tool! See "farm tech tip" in earlier post on how to modify a common 1/2 inch wrench to do the job. Not exactly workshop manual factory approved but it works well for those who aren't hypnotized by the Snap-On logo! :lol:

Mike
Kansas, America
73 850 Roadster y mas, y mas
 
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