Gas consumption is way too HIGH, Mileage too low

[TopCatGr58]

Hey Rich,

The cam chain galley is a no pressure environment....just slung oil! I would hate to see you pull the head for just that little leak. Are you SURE it's leaking from between the head and cylinder/jugs?? It's more common for it to come from the valve cover and gasket. I would clean the area very well, apply some corn starch or talcom powder to try to verify where the leak is coming from.

I would only use the hotter plug in the #2 cylinder, the others are burning just fine.

As stated, it could be a valve GUIDE seal....a bit more troublesome to replace, so would really suggest a peek at the valves thru the intake port before thinking about taking the head off. The Exhaust is closed except on the exhaust stroke, and so even if that seal was leaking, it wouldn't get a chance to get into the cylinder being always under compression/positive pressure and not VACUUM like the intake valve.

I'll have to defer the head gasket sealant to others that have done and used it, but I think you'll need to rule out other things before deciding that you need to pull the head.

T.C.

[RichV]

Yes, it is the head gasket. At the seal right above the cam chain tensioner. A little bit of oil is leaking out with a bubble of air. I will try and re-torque the head bolts tomorrow to see if it stops.

I will also pull the carbs after it warms up and see if the intake valves are leaking at the valve guides.

I also plan to take the valve cover off and double check that everything is lined up correctly and the clearances on the valves. It's relatively easy to do.

I noticed in another thread that the cam sprockets are supposed to be installed with a mark next to the bolt on the top bolt. I'm not sure I did this and want to check it. If I did it wrong, the valves could be slightly out of sync with the piston stroke. It may not be the cause but it needs to be double checked.

I couldn't get the plugs today. The guy at the parts counter kept bringing the wrong plugs so I gave up. I'll visit a different place tomorrow and get them.

[RichV]

Well I removed the carbs and valve cover today. Here is what I saw on the #2 cylinder intake, exhaust, and pipes (1 and 2).





I checked the clearances and found that the intake side needed to be tightened up to spec. The exhaust side was fine. I also checked the installation of the chain, sprockets, and cams which were all okay.

Inspection of #2 shows a clean intake (no oil), clean cylinder head (through spark plub hole), and very dirty exhaust and pipe. You can see that the #2 pipe is "wet" and so is the exhaust valve. No sign of leakage from the valve guide but it was hard to tell with everything black.

Carbs checked okay. All jest in place and floats correct.

Tomorrow, I will check the torque on the head bolts. Even with the exhaust the way it is I'm still not certain where the oil is coming from (valve or rings) and why the plug fouls. Changing the valve clearance may have a slight impact on when the intake valve opens during the intake stroke.

[DiverRay]

Keep in mind the INTAKE valve can also have a bad seal, and you would NOT see the oil! It would be pulling oil on the intake, and as you slow down on compression. You probably could have looked as you came down a hill to see if there was smoke from that side, or from the exhaust at all.

[GLoweVA]

Yes, it is the head gasket. At the seal right above the cam chain tensioner. A little bit of oil is leaking out with a bubble of air. I will try and re-torque the head bolts tomorrow to see if it stops.

This is the part that I keyed in on.

A couple of years ago, I burnt a hole in my piston and the combustion that occurred in that chamber pressurized the crankcase area. It was so bad that I blew out a valve cover cam plug.
Granted this is a ultimate worst case and you are no way near that.
But I believe there's something that's causing a pressure rise in your case.

That area at the cam chain valley should be at or near atmospheric pressure. If there's pressure building up in your case 'forcing' the oil out between the head and jugs (head gasket) then something is causing the pressure increase.
It could be something like the rings (on #2) aren't doing an adequate job and thus you're getting blow-by and oil fouling of the plug.
The compression numbers on #2 may be a little suspect because of the intake clearance being a little big. (less time for the valve to be open, thus higher compression) I would surmise that after you re-shim #2 intake, try another compression test and see if #2 goes down compared to the other 3. That might be a little tell that there's something else going on in that cylinder.

I'd hate for you to have to pull the jugs again cause I know what a royal PITA that is. (actually pulling is easy, putting them back on again is what sucks) I've done it twice now. Once in the bike and once out of the bike.

Just another thought/question:
If the exhaust valve guide leaked by, how would that oil get into the cylinder to foul the plug? Wouldn't every time the exhaust valve opened the pressure in the cylinder tend to 'blow' out anything in that exhaust plenum?
Now on the intake side, hell yeah, any oil leaking past the seal would get 'sucked' right in on the intake stroke.

[MPittma100]

Cylinder Leakage Test

Even though the compression numbers appeared to be very good, I would reconsider checking the cylinder leakage on all 4 holes. Just a good procedure to eliminate or identify a cause of any problems.

The compression numbers and the evident problems are not adding up.

[bikerphil]

May have broken/not correctly installed the oil control ring upon reassembly, there would still be good compression but poor oil control, JAT

[3Phase]

The cam chain gallery doesn't really stay at atmospheric pressure, it's got a pretty heavy pulse with the piston pairs moving up and down and the normal amount of blow-by.

It more or less equalizes out in the rest of the case as it heads to the crankcase vent in the rear corner but it'll do a really good 'Puff, the Magic Dragon," that turns into a decent stream as the engine speed goes up.

Yes, I was wondering about it one fine day so I fired up Columbo with the valve cover loose. You probably would believe me if I told you exactly how fast an XS1100 can throw oil off of the the cam chain, out of the cam chain gallery and all over the engine and the total moron working the throttle.

.

[RichV]

Yes, I was wondering about it one fine day so I fired up Columbo with the valve cover loose. You probably would believe me if I told you exactly how fast an XS1100 can throw oil off of the the cam chain, out of the cam chain gallery and all over the engine and the total moron working the throttle.

Oh yes. It's easy to underestimate the power for fast moving parts.

[RichV]

Stopped at the Yamaha dealer (Casey Cycle City) and swapped out some shims. These guys are really helpful. I was charged $4 per shim which is reasonable. I also found the hotter plugs.

Today, I removed the head and found some interesting stuff. The previous photo shows #1, #3 and #4 all looking okay with #2 having darkened valves and a clean piston (see photos below). Tomorrow, I will raise the jugs to see if the oil rings are okay and installed correctly. I don't think they are.

I will also check the seals on the #2 valves and make sure the valve guides are okay. If they #2 is bad, I will look at ALL of the valve seals. I may also check #1 since the exhaust valve has darkening around it. I changed all the seals and re-seated the valves during the rebuild.

I noticed that the oil from the cam chain area was on the head gasket. It could have happened when I remove the head. I also noticed that the head bolts were not as tight as I would like. When I put it back together I plan to use a copper sealant on the gasket to make sure it doesn't leak. I'll also check the torque on the bolts after the first ride.

Here are today's photos If you see anything let me know. I did check to make sure the head and jugs are still flat. It hot here in VA right now and I can only last a couple of hours in the garage at a time.

[GLoweVA]

Rich, it looks like #2 isn't getting any combustion at all!
There's no discoloration around the rim at the top and the piston top looks brand new.
The other 3 sets of valves look about right for normal combustion, just like your plugs.

If your compression was good, then I think that the rings are okay.
It may just be that plug wasn't firing, or you weren't getting enough fuel/air mix in there for it to combust, therefore what little oil that normally would get burned up didn't and collected around the exhaust valve as it got 'blown' out during the exhaust stroke.

Check the intake boot for #2 and make sure it's seated up tight.
I had a bolt come loose once there and it sucked air in at the joint and didn't suck in any fuel from the carb. The bike ran poorly.
One thing you can do once you get the head back on, is before you put the carbs back in, try running the starter(ie crank it over) and see how much #2 sucks compared to the others.
Plus, that will be a great time to check compression again. (no carbs to have to hold open the throttle)
Also check that the #2 carb is delivering fuel okay.

Pictures are worth a thousand words and those 2 pics tell a lot.

On a different note, what is your travel plans to XS SE? Trailer, truck or ride?
I haven't finalized my plans yet.

[RichV]

Thanks George,

I checked the rings today and all of the valves seals and guides. Everything was okay. Tomorrow I'll reinstall the head and adjust clearances. I'll then run the tests you suggested.

As for XS SE I will be visiting my mom in TN the week before or after. I also plan to camp like last time. I would like to ride but I don't have the ability to carry much so probably will just load up the bike in my truck. That said things are still fluid and can change.

If I ride I need to get a windshield installed. Too much wind for too long fatigues me and shortens my ride time.

[bikerphil]

I checked the rings today

Does that mean the 2 bottom rings are 'clocked' correctly and no overlapping of the wavy oil control ring? I have seen them installed wrong on motors and that would make them intermittently smoke.

[RichV]

Does that mean the 2 bottom rings are 'clocked' correctly and no overlapping of the wavy oil control ring? I have seen them installed wrong on motors and that would make them intermittently smoke.

I did when they were originally installed and only exposed the oil ring on 2 and 3 this time.

[TopCatGr58]

Hey George,

I was thinking a bit more about this. Rich says that it does have combustion and runs good for 20 or so miles before it finally fouls, and then he is able to sense that it's not runnin right. So...then after the plug oil fouls, he then no longer has ignition, but the carb is still working and so the cylinder is then getting washed with FUEL for the time he runs it with the fouled plug. And thats why I think that cylinder and head looks so clean compared to the others with burned on carbon deposits.

He pulled the head, inspected the valve seals, the rings, etc., so not sure why he was/is getting the extra oil slipping by and eventually fouling the plug. I know he said he swapped coils....and also I think he then tried swapping plug wires 2-3 and the problem stayed with the cylinder.

I know the comp. piston ring has a right side up, and I thought the scrubber ring also had an orientation to help skim the oil back down the cylinder.

IF he got the scrubber ring upside down, that could allow the oil to slip by even if the OIL rings were properly installed and stagger gapped.

SO...Rich, just have to ask if you verified that the 2nd piston ring was oriented properly?

T.C.