Houseowax,Thanks for the encouragement. I'm relieved that it was a simple fix also and won't cost me a lot more $$.
This forum has also helped me immensely also.
I have a handle on most stuff but this was my first engine rebuild. I did the engine work before I knew of the forum and without any specs.
This bike was a real disaster when I got it. It sat outdoors unprotected for years and was a rusted hulk.
I bought it as a parts bike but since it had a title I figured why not fix it up.
Hope to get back together in the next couple days.
engine blowbyBut the good news is that you can pull the motor, rip parts off and replace them with growing confidence.
The small hole in that alloy plate creates a separation chamber above the cam where oil separates out from the air ( to an extent) and returns to the crankcase. If the holes are at the rear, the oil slowly fills up that chamber until it passes the breather outlet and at that point it either pukes oil out of the breather or pressure builds up and oil is forced out of everywhere and the thing bleeds out. If teh palte si left out then there is no separation chamber and oil thrown off the cam sprocket plus all teh other oil mist churning around up there can go straight out the breather. In your case it sounds like there is excessive pressure in the crankcase trying to escape. There are a few possible causes, but the most likely IMHO is worn or sticky rings allowing some of the combustion gases to get past the rings and to pressurize the bottom end. I would get those spare barrels to a machine shop and have them bored to suit a new pair of pistons if they say that the originals are a problem. With your motor we don't know, because the top didn't come off this time. But there's nothing that says it has to be done now while there are roads to ride and sunrises and sunsets to watch from the seat of a bike. Mike, I must have missed that earlier. How were the barrels when you slipped those in? Were they measured or just looked OK?
If the bores were within limits, they still need to be glaze busted as a rule to allow the new rings to seat. What tends to happen is the bore surface gets shiny and hard (not exactly a technical description, but you get my drift) and new rings just slide against that surface rather than bedding in. You can do a leakdown test and see what's going on. I use a good Tavia leakdown tester and set the compressor to 100PSI. The trick is not to allow the motor to turn over suddenly because that can cause all manner of problems including missing digits. If it doesn't hold the pressure well, you will see it on the second gauge and you will also be able to hear air escaping through the area that leaks. If it's the bores, you can hear air seeping/hissing past the rings. I like to get 2-3% leakage but can live with 10% on a street motor. If it's the bores and the pistons and rings are still fine, then the cheapest way out may be new liners bored and honed to match those new pistons. Maybe when LM gets back, he may have a better idea. BlowbyTeazer, if Mike is making 125 lbs of compression isn't that within limits (assuming it is in both cylinders)? I am finding conflicting numbers on this, but it looks like the Honda Shop Manual numbers are 150 lbs normal with 113 lbs lower limit at least on a CB. Bill Silver says normal is 150 to 175 for all 305's.
What say you? If Mike's compression is within limits would you still suspect leaky rings? What about exhaust valve guides?
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