I happened to notice something I thought was strange. Check out the piece paper in exhaust port 4...what are your thoughts? It appears to be oil..could this mean there was oil in the cylinder? That along with the oil seen around the seals could mean I have a leaking head gasket?

When I bought the bike I didn't notice any oil leaks/issues (although I was clueless then, so I probably don't remember any issues in that regard since I didn't know what to look for) and I've put about 2k miles before starting this disassembly.

Before the diss-assembly, the bike ran well. Engine had plenty of power, no flatspots, good powercurve. The only engine remark the tech made when I had the bike inspected before purchase was: "Idle circuit seems to run on 3 cylinders" I did notice some stuttering when letting out the clutch and giving it no gas, but I have a feeling that is normal.

 

Does the paper smell of gasoline? Just wondering if cylinder number 4 isn't firing properly and there was still gas in the cylinder.

If it is actually oil then it could be the head gasket but the valve seals might also be worn and oil could be leaking down the valve stem into the exhaust port. How many Km's on the engine? It looks like there is some oil on the paper from the 2 and 3 ports as well.

I would possibly try and clean out that exhaust port and then put some fresh paper in and see what part of the paper picks up oil first. That might help tell where it is coming from. That's my first thoughts after looking at the pictures.

 

I just had another thought that you should probably look at the plugs and see what state they are in. That will tell you how the engine is running and if oil has been leaking into the cylinder while the engine is running.

 

Its very hard to tell from just pictures. It looks like oil, but so do the other paper towels. the darkness on the paper towel looks to be nothing more than carbon build up. If the bike doesn't smoke or use oil. I really don't think you will much to worry about. It doesn't take much oil to make a lot of smoke out of your exhaust, so if its not smoking, your probably ok. Look for smoke at initial start ups. that will be a sign of bad seals.

Its always a good idea to look at the plugs for indication on how the engine is running like already suggested. The only downside to this situation is the bad seal could be on the exhaust side. If the seal is bad on the exhaust side, chances are it won't enter the combustion chamber as it will be blown out the exhaust while the engine is running. It will still enter the combustion chamber when the engine is off, and the plug will still show some signs of this. It just might not be as obvious. But look for any signs of a crusty whitish gray coating on the plug. That will indicate oil burning.

Generally, a leaking head gasket would introduce coolant into the combustion chamber, not oil.

I also agree that its more than likely left over gas in the cylinder. That cylinder was probably still on the intake side when the engine stopped. The other cylinders were more than likely closed. When the engine is shut off, all spark is stopped and your going to have at least one cylinder have gas shot into it without it being ignited, at least more so than the others. It will sit in the cylinder until it evaporates over time.

As for the dirty spots on the engine. Its hard to say what that is since debree lands in strange places. You have a radiator, exhaust pipes, and all sorts of things will contribute to dirt gathering one side of the engine but not the other.

Now would also be a good time to do a leak down test and a compression test. But there is nothing I see that screams problem to me.

 

To reply in order:

The paper does not smell of gas, it most definitely smells of oil.
The engine was last run ~2.5 months ago and has been sitting with the oil drained for ~1.5 month at this point in time. Some oil is present on ports 2,3 and a very very tiny amount on 1(not visible in picture). The oil appears to come from the top of the paper, so top of the cylinder, therefore valves?

More oil has accumulated on port 4, so it must have taken a while for the small amount of oil to leak down.

The engine has < 25000 miles on it.
I've never noticed smoke on start up.
I'll attach pictures of sparks, cylinder 4 => cylinder 1. They look pretty normal in my opinion, but I'm no expert and a pretty new wrencher/diagnose.
I'm sure of the order of the plugs (#2 looks worst right? why?) as I put numbers on the upper white when I took them out, you can see a 3 and a 1.
Bike has a jet kit, yoshi rs-3 pipe and k&n air filter.
I'm completely clueless in this regard..but I had assumed that after 2.5 months, all the gas would have evaporated from the cylinders?

I'll look into what a leak down test and compression test is. Sounds like both may need to wait as the bike needs to be reassembled before any of that can happen.

I've heard and read that what I've found may be due to valve guide seals being old and needing replacement. I'm almost considering doing this as the weather has yet to get better and it's still raining a lot of the time. I don't mind tearing into the engine, albeit my first time; so I'm a little worried, but I feel I'm an ok wrench. Heck..I took the whole bike apart without major issues and figured everything else out. My only concern with this is not having found a proper guide online and my Clymer manual is informative and whatnot, but honestly: confusing.

I'll clean those dirty spots and see what happens when I have it back up and running.
I appreciate the replies!

 

My apologies if I missed it. But what year and model is this? The mileage is not a concern as these bikes can go well over 100k without needing any serious attention. However, if the bike has sat for long periods of time, that can dry the seals out. I would by a higher mileage engine that was consistently ran over a lower mileage engine that sat for long periods of time any day.

To me, the plug on the far left seems to be the worst with the one next to it being not far being. There are deposits on both of those plugs which could be an indication of oil burning. Normally, too rich, gas additives and oil will leave deposits like that. But, it doesn't appear to be very much if that is it. Having said that. it honestly looks like those two plugs just have more miles on them. The only reason I would lean towards some oil burning is because they are next to other plugs that do not have the deposits. If the plug was by itself, it would look like a normal higher mileage plug. But, that is a good amount of deposit for only 25,000 miles. Also, if your carbs are not synced just right, you could have those cylinders just a bit richer at certain rpms which could cause the same thing.

Its up to you where to go. If you put new seals in, you'll know 100 percent that they no longer leak. But, it really doesn't appear the leak is bad enough to warrant a tear down. If it was me and I didn't see any smoke and wasn't loosing oil, I would run it the way it is. There is quite a bit involved with removing the head and valves for someone who has never done it before. Not to mention the special tools required.

 

Update: I've basically decided to not take apart the engine as it would simply be too much work for me and in the end would bring me aggravation and frustration. The whole point of me owning a bike is to ride as it makes me superbly happy. If I start seeing smoke come out of the exhaust and oil being eaten up and performance dropping...then I'll consider it since it would make me happy to have something running well.

Squid: Bike has 24k miles, has been run pretty consistently from what PO told me and I've ran it pretty consistently as well for the time I've owned it. I'll monitor the sparks now and then and will need to do a carb sync when I put it all back together and get it running and road ready.

Thanks to all for input!

 

Shiffts,

Probably a wise choice. If the engine has been running ok then it's good to enjoy riding the bike and not dealing with problems that might not be there. It's also a lot of work to take on. I've been doing valve and carb work on my bike intermittently for the last couple of months and it takes time and effort to deal with these problems. Good idea to keep and eye on oil use and plug condition though.