Head Games! What did we find? 1978 Yamaha XS1100. Video #3

Head teardown on the 1978 Yamaha XS1100. What did we find? Watch this video then watch Video #4 which will be uploaded right after this video has processed. There are problems with the valve stem seals which I have never seen before!

[@fastchip]

Nice update. Make sure to tell the customer though, if there is still smoking / oil consumption its on him for not replacing the rings.

[@MotoRestoFL]

Watch video #4 the next one. I uploaded both back to back for this reason: cylinder block is off the bike, honed up and rings are on the way (or at least ordered). You all were right, oil control rings as flimsy and inflexible as my ex-wife. hehehehe

[@RickyBobby615]

Just an FYI, in the upper case between opposing cylinders is a hole that sends the pressure between cylinders back and forth to expidite pressure relief rather than fighting rotating oil and crankshaft. Used this mod on my z1 back in tha day.

[@MotoRestoFL]

Not sure I understand. You're saying a hole is there but then saying it's a modification to be made?

[@RickyBobby615]

@@MotoRestoFL I was mistaken, Its an 84 FJ1100 - Cycle World Magazine Jan-May 1984 (google books) Page 36.

[@MotoRestoFL]

@@RickyBobby615 I’ve read Kevin Cameron’s material on cylinder down stroke balancing. I’m familiar with it. The engineering is interesting. If memory serves, there’s pros and cons about the crankcase pressures in a variety of setups including these type. Cheers.

[@karlvanboxel561]

Prob leaking oil between the valve guide and valve stem seal and down into the chamber!

[@huntterhacker4529]

I got an 1980 xs1100 recently and I’m still kinda new to bikes but it’s blowing oil out the crank case vent and I mean a lot a quart in 2 seconds but it’s only when it’s in gear I’ve looked everywhere and no one knows y does anyone got any idea what I could be

[@MotoRestoFL]

The crank vent on the top rear of the engine? I have a 1980 engine sitting here, I can't see how that would happen unless the oil is way overfilled. So at an idle if on the center stand you bumped it into gear and without any throttle, the thing starts pumping oil out of the breather? I can't see how that can happen just when the transmission is engaged unless it's just super overfilled.

[@huntterhacker4529]

@@MotoRestoFL see that’s what I was thinking cuz it runs amazing but I filled it up even just half way and still all shot out my next guess in the oil pressure relief within the oil pump but I’m not sure

[@MotoRestoFL]

@@huntterhacker4529 I have no idea. But when you figure it out I’d sure like to hear the story.

[@MotoRestoFL]

You may be onto something. I pulled out my XS1100 manual and examined the lubrication chart. The pump has an pressure relief "plunger" valve with a spring shown in the parts breakdown. The lubrication chart shows the flow starting at the pump, into the filter, then besides the crank the next thing to get oil is the transmission. Then the top-end. I wonder, if the relief valve is stuck open, the spring is weak or even broken and perhaps it's pumping too much oil pressure? Possibly that transmission being the path of least resistance for the oil, it's over-lubricating the shafts. That vent is also known as a middle transmission vent besides engine crankcase vent. Since it only does it in gear, I wonder if there's too much oil flow to the primary, main or drive shafts or all three and slinging oil right at the vent and puking out. Worth a try to check. The oil pump is, as typical to these engines, inside under the sump cover, so you'd have to pull the exhaust and drain the oil and pull the sump cover which I know can be done on the bike with the engine in situ. Let us know what you find.