Bingle

Went out in the woods to get a load of firewood. Coming back down the hill with the bed loaded down, using first gear and no throttle to keep it going slow/help with braking, was getting a decent amount of smoking out the tail pipe. Driving normally on the roads I wasn't seeing any smoking. Some black greasy residue in the tailpipe at the bottom of the hill so looks like I was pulling oil in during compression braking. Haven't pulled the plugs yet.

So, what are your thoughts on the cause of this? Valve stem seals? Piston rings? Other?
Also, per my signature, it's dual sidedraft webers, so no pcv, just breathers on the valve cover. Also have about 80-100K miles on my rebuild.

Thanks.

cbr600rx7

That's a tough one. At first I was going to say PCV but since that's not a issue for you I am stumped. How's your compression because I am thinking rings possibly.

Bingle

I checked compression about 8ish months ago and it was still "fine" but am thinking that I need to check it out again. Was thinking that I was getting close to due for quick hone and new rings. Probably a valve lap as well just to get her back up to tip top running order. The engine still runs well and pulls strong, just not as well as it did when the rebuild was more fresh.
I'll pull the plugs and check them and do a compression check soon and will post back with results.
The engine is in need of a bit of tlc. Leaking oil pretty well out the back somewhere that I haven't pinpointed yet.

Is there an oil passage through the egr plate on the back of the head?? Looks to be possibly leaking there or maybe (worst case) head gasket at the back of the head. Guess it could be the rear main, but I'm getting oil on the lower back side of the head. Half moons and valve cover gasket does not seem to be the culprit.

Thanks for the input and keep it coming.

Old83@pincher

Valve stem seals. IMO those half moon seals are always leaking or just about ready to leak! That plate at the back of the head is another "problem" spot too for leaks...anti-freeze not oil.