Author Topic: 350 miles after rebuild and have an oil leak  (Read 2306 times)

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Offline Scott S

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350 miles after rebuild and have an oil leak
« on: June 23, 2012, 04:22:57 PM »
 Just did the top end on my '78 CB550K (overbore, head, etc.), so basically new from the case up. I was pretty thorough about cleaning the surfaces, used new gaskets and copper gasket spray on the base and head gaskets. Torqued everything to spec and in sequence.

 The first ~250 miles were fine. In the last 100 miles or so I've noticed some oil. At first I thought it was from the base gasket. Mostly RH side, just above the points covers, where the cylinders meet the case. There's a tiny leak on the LH side as well.

 Upon close inspection with a flashlight and paper towels, there MIGHT be oil coming from the head gasket as well. What seems odd to me is that there's oil between the fins on the left and right side of the engine. I don't see how it could get there. The cylinder fins are solid in that area, right? No oil in front or rear of cylinders.

 If I can make it to, say, 1,000 miles (first valve adjustment), can I pull the valve cover and retorque the head? Think that would help? Suggestions?
'71 CB500 K0
'17 Triumph Street Scrambler
'81 Yamaha XS650

Offline lucky

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Re: 350 miles after rebuild and have an oil leak
« Reply #1 on: June 23, 2012, 04:47:55 PM »
I would re- torque the head now. When the engine is cooled down.

Maybe a locating dowel was too high for the gasket you used?

Offline Scott S

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Re: 350 miles after rebuild and have an oil leak
« Reply #2 on: June 23, 2012, 04:52:12 PM »
 Maybe. I just read the "leak free top end" thread and, even though it's for the 750, I see where they mentioned that.

I'll be resealing the top end on a CB500 engine soon. It was rebuilt, ran for ~2,000 miles and then sat in a barn for 28 years. It runs great but got really oily around the head. I figured the gaskets and pucks dried out from sitting.
 Are there any sealers I should use when I do it so I don't run into the same thing?
'71 CB500 K0
'17 Triumph Street Scrambler
'81 Yamaha XS650

Offline lucky

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Re: 350 miles after rebuild and have an oil leak
« Reply #3 on: June 23, 2012, 04:54:19 PM »
Maybe. I just read the "leak free top end" thread and, even though it's for the 750, I see where they mentioned that.

I'll be resealing the top end on a CB500 engine soon. It was rebuilt, ran for ~2,000 miles and then sat in a barn for 28 years. It runs great but got really oily around the head. I figured the gaskets and pucks dried out from sitting.
 Are there any sealers I should use when I do it so I don't run into the same thing?

My choice is the tradition GASKACINCH brand.

Offline bryanj

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Re: 350 miles after rebuild and have an oil leak
« Reply #4 on: June 23, 2012, 05:22:57 PM »
On the bolt that holds the steel bracket the end caps fix to there should be a soft alloy sealing washer between the bracket and cam cover, if that is missing or deformed  you will get a leak.

I have NEVER done, and Honda do not recommend, a re-torque
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline Scott S

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Re: 350 miles after rebuild and have an oil leak
« Reply #5 on: June 23, 2012, 05:29:08 PM »
 It's not leaking anywhere near the end caps. Would that cause a leak around the base gaskets?
'71 CB500 K0
'17 Triumph Street Scrambler
'81 Yamaha XS650

Offline adamlwvdc36

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Re: 350 miles after rebuild and have an oil leak
« Reply #6 on: June 23, 2012, 07:09:39 PM »
on my 550 I had a similar problem.  seems that you almost have to go to far with the torque, back off again and then torque to specs.  I know its a bit unorthodox, but this is what took care of the problem for me.  btw, go to autozone, buy some oil uv dye and put it in with your oil, run the bike briefly and then shine a black light on the engine.  Anywhere the oil is coming out will glow so you will know everywhere you need to observe.  while you got it apart (if you do) use some permatex indian head shellac... great stuff and cheap too.  I finally gave up on the gaskets and have just the shellac between the case and my cylinders 
_ADaM

Be a COWBOY, not a NERD!  youre riding an antique bad ass motorcycle for God's sake...

75 CB550 Named "Don Casper"  Don for grandpa, Casper for the guy that mentored me to riding... RIP Kenny...