So far I've:
• Replaced spark plugs
• Adjusted point gap & ignition timing
• Checked and adjusted valve clearances
• Fully disassembled and cleaned carbs
• Replaced petcock, installed an inline fuel filter
• Replaced front brake brake master cylinder, brake lines, and pads
• Beaten my head against the wall
Right now it runs, and is rideable, but it appears that cylinder #3 is doing all the work. I initially determined this by idling it and disconnecting the plug wires. Disconnecting wires 1, 2, and 4 made almost no difference, but disconnecting 3 kills the bike. It should also be noted that one its heated up, a lot of blow-by gas comes out of the crankcase breather, which is currently just running to a uni filter.
I did a compression test, and these are my dry/wet numbers in psi. I forgot to hold the throttle open when I did the test, but can easily re-do it if you guys think it would make a significant difference.
C1: 60/180
C2: 64/130
C3: 160/off the chart
C4: 65/140
So, this would indicate piston rings. Right? however there's this weird symptom. Air blows OUT of the carbs on the cylinders with low compression, and a quick air hiss can be heard on every stroke. Here's a video so you can hear what I'm talking about https://www.icloud.com/photos/#0Yo1L...QLxdpikgqEMP3g
So, am I looking at Valves AND Piston rings, or is this possibly a cam timing issue? To make sure I wasn't crazy, I re-checked my valve clearances. I thought for sure the intakes were just too tight. I had not checked them using the meticulous "suzuki" method when I did the adjustment. Alas, they're within spec anyway. Intakes are a little on the tight side, all .04mm, with cylinder #3 at .06mm.
This is starting to look like something that an "italian tune up" isn't going to fix, but I want to make sure there isn't anything else I should be trying before I resolve to do a top end rebuild.
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