Author Topic: Observations on rebuilt motor  (Read 795 times)

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Offline Burnboy

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Observations on rebuilt motor
« on: June 08, 2009, 01:23:45 PM »
So I'm nearing the end of my rebuild. All I have left is the front brakes to do. Took it out today for a short trip around the neighborhood then some light revving in the driveway to tune the bugs out. Im running very rich which I can tune out of it, got flames coming out the exhaust from time to time. But my major concern is that I have frothy oil.

Opened up the oil bag to check the level and notice that I have bubbles on the top, not many, but then again I haven't ran it too long either. Oil smells a lot like fuel as well, now I'm kinda freaking out. Also after turning the throttle a bit (about a minute in the driveway) I hear a ticking noise from the top end during cool down, hoping this is the valve cover just settling in and needs some tightening.I plan on changing the oil out in about 100 miles or so, if no major problems present themselves first.

Either this is something serious or im hoping a combination of a sew small things.
1.Valve cover is weeping a bit, just seen to tighten it up
2.Oil is a bit overfull, just a hair over the top line.
3.Piston rings haven't had a chance to set yet.
4.Valves haven't set themselves either.

So do I need to be scared immediately or will I be ok for a hundred miles and then asses from there?
« Last Edit: June 08, 2009, 01:37:02 PM by Burnboy »
1975 CB750
1973 CB350F

Offline B.O.X.N.I.F.E.

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Re: Observations on rebuilt motor
« Reply #1 on: June 08, 2009, 03:38:31 PM »
It's frothing because it's over filled. The levels are there for a reason. You need to be careful how you break in a rebuilt motor or your rings won't seal and you'll end up right where you started - with low compression. I just did mine and have been breaking it in the last couple days.
1974 CB550

32 days and 5,536 miles on a CB550...

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and a couple years later, 38 days and 9,102 miles...

Forever West

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Offline Burnboy

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Re: Observations on rebuilt motor
« Reply #2 on: June 08, 2009, 03:41:09 PM »
thanks boxnife, Ive been reading up on all the ways to break it in, of course they all vary  but all have similar instructions for the first 20-75 miles.
1975 CB750
1973 CB350F