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Let me tell you about my weekend. I rebuilt my engine Friday, started it up and it sounded pretty good, there was a slight intermittent metallic ping and backfire from the rear cylinder. I had it bored .005" over, got new +.005 HD pistons and ring set, had the valves/heads done by a reputable machine shop, new lifters and adjustable push rods and an Andrews ev27 cam. Zero deck height and .030" head gasket
It had a little intermittent soft, but noticeable ping and backfire from the rear cylinder, but it sounded like a Harley should and I figured that's just what the cam does. I put it through 5 heat cycles , changed the oil (not the filter) and then put about 45 miles on it and parked it.
Boy it pulled like a freight train. It feels almost like my buddy's 103. I was so excited. It felt like it was running perfect, putting down a whole lot of torque.
Saturday morning i go out to it and notice that there was a little oil spray on the right sode of the bike, i figured it was just a little coming out the air filter until things get broken in. I started it up and it idled fine, no ping, no backfiring, then i gave the throttle a blip and wow white smoke come pouring out the rear cylinder exhaust. So much smoke it looked like my bike just hit a vape. I shut it off immediately and havent run it since.
I took an endoscope to it today to see if maybe I screwed up the piston rings or maybe had the rods adjusted too far out to make the valves hit the piston, but the surface of the pistons look fine. Maybe a little pitted or something, i don't know how that could happen, maybe a speck of rust from the gas tank got sucked in or something and was causing the ping
What could be the cause of burning oil from just the rear cylinder and also spewing it out the air cleaner?
I have a couple theories, maybe the old oil filter is plugged or gummed up and is causing oil pressure to build up and get pushed out the breather/ac and out the piston, up around the rings into the cylinder? Or maybe theres an oil passage plugged up somewhere else? Maybe because my engine is making a lot more power its pushing the oil pump too hard ? I didnt overfill the oil reservoir.
I'm going to tear down the top end this week, what should I look for?
Last edited by Scottyxbones; Jun 23, 2019 at 07:21 PM.
I also stuck the endo in the sparkplug socket in the front cylinder, I see a splotch. Does that look like a bad splotch to you guys? What caused that? The front cylinder isnt burning oil as far as I can tell
BHG? I've seen that puff out lots of smoke. Otherwise, maybe a damaged piston. Not the oil filter. Not the increase in power. Pitted cylinder and pinging can easily destroy a piston. Look for damaged ring lands.
Hmm, maybe the gasket got shifted when I put the head on. Is there a certain technique to keep it centered while you set the head down on it? Its an mls gasket, I followed cometic's instructions to torque down the bolts...
You have locating dowels on the cylinder to locate the head and head gasket so I doubt you accidentally shifted the head gasket during assembly. Often those will be removed and tossed out by the shop doing the machine work. Did you or the shop replace them?
Who measured, fit, and installed your piston rings?
Some things that come to mind (besides what has been mentioned) are a cracked piston ring, maybe an oil control ring installation issue (those can be tricky). How about breather gear and cam timing marks properly aligned during reassembly?
Just shooting from the hip, don't really know your experience level, how thorough you are, or if you double tripled checked things, etc. YD
Last edited by Yankee Dog; Jun 23, 2019 at 08:29 PM.
Not condensation right? Do a compression check before you pull the heads. New umbrella vlaves, and put on correctly? Could also be that you have a bad valve guide seal. Sorry for your issue. Hope you find the problem.
Last edited by daven9113; Jun 23, 2019 at 09:49 PM.
Not condensation right? Do a compression check before you pull the heads. New umbrella valves, and put on correctly? Could also be that you have a bad valve guide seal. Sorry for your issue. Hope you find the problem.
If the motor is a head breather then I suggest the same but make sure you use OEM umbrella valves instead of aftermarket.
Before you do anything else route the breather to atmosphere instead of to the carb.
What THC said about relocating breather hoses. And, you said “white smoke”, not gray or black.
White is usually steam.
Where did the water come from? Bad gas?
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How bad is this cylinder? And burning/blowing oil
