Topic: "Fried Intake Valves" 1976 CB550

[scottly]

Ouch!!

[Can550]

I'm terrified
Don't know what next?
Damn I spent four days taking parts off, scrubbing, cleaning, polishing them

Even ordered a set of tyres, bought oil, filters and brake pads, all led bulbs and a headlight. I'm sad


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[scottly]

Is the camshaft itself broken in half, or is the broken off ear where the sprocket bolt goes the only breakage?

[Can550]

Ear is broken (to the best of observation). Are you suggesting it can be salvaged ? I don't even know how much these go for used and or new


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[scottly]

No, I wouldn't try to salvage the cam; I was asking to determine the cause of the breakage. From the looks of the damage, I'm guessing the sprocket bolt backed out until it hit the cam cover, snapping the ear off. If the shaft itself was broken, one might suspect that oil starvation may have caused the cam to seize, breaking the cam and breaking off the ear. If the bolt backed out, most likely due to improper assembly, the damage may only be to the cam itself, rather than the cylinder head and cam bearing surfaces.

[bochnak]

Now would be a good time to check cam timing. If cam timing is good, then the valves should be OK too.

You can still perform a leak down test with the cam out. Just support the cam chain in case the crank wants to spin on you.

[lrutt]

I'd also replace that cam chain as it has seen a lot of stress. Pretty strange failure to be honest.

[DaveBarbier]

Other options are to get another 550 motor that runs and drop it in your frame while you fix/upgrade this one. Or...of course there's the 650 swap which drops right into your frame too . Sometimes it's cheaper to get a whole bike that's been sitting instead of getting individual parts. My 650 donor cost $300.

[Can550]

I feel this is exactly what happened. You are right on that. Seeing the spot where broken bolt was sitting.

I have found one camshaft locally, waiting to talk to seller in case he has rocker arms from same setup so they match.

If it is pricy, then I'll put bike in a corner and wait to come across a cleaner running motor. Thanks


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