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Discussion Starter #1
My 2000 is on the lift with "tupperware" removed for BMW "Inspection" at approx 95K miles.

She's been using oil beyond what I find acceptable, having to add oil every day on long rides or every couple of days of short rides.

I did a compression test and cylinder leak-down test a while ago, everything normal.
I suspect a cracked piston land so have decided to do a visual inspection of the pistons.

History: No visible oil leaks. It does smoke more on start up than it used to. Friends riding behind me have commented on smokey exhaust but it isn't that severe because I can't see it in the rear view mirrors. I have ridden hard over the years, two up, pacing some of the sport bikes in the hills, so the engine has been hammered pretty hard; basically getting all she has to give it terms of rpm's to the redline. I did have my air temp sensor unplugged for the hot weather hesitation issue for a few years but always ran premium gasoline. I plugged the sensor back in and left it that way since I'm not troubled with really hot weather very often. Other than that, there is no significant history to the engine that I can think of.

I'm no stranger to engines but will be venturing into the LT where I have not been before, so hope to get input and suggestions from my pals Saddleman and jzeiler or others with experience when questions come up.

I'll try to remember to take some pics so I can post and share a little of what I learn.

I have both Clymers and the BMW Service Manual; I'm used to the BMW Manual so I'll use that unless I get confused by it and then I'll check with Clymer.

This is what I expect to be doing tomorrow: sequence according to the Service Manual: 1)remove radiatiors, 2) remove exhaust, 3) remove fuel rail, 4) remove throttle butterfly rail with air silencer, 5) remove timing case cover, 6) remove timing chain.

Questions right now: Should I zip tie the cam chain to the cam sprockets when removing the cam chain? Will that make reinstallation easier and reduce the risk that I'll get the valve timing wrong, or will that just increase the hassle?

Should I do a "preemptive" change of the O2 sensor?

I've done valve jobs on small engines, and lapped the valves on a couple of Airheads, but I think I'll send the K1200LT head out for a professional going through. Any idea who to send it to? I'm wondering if valve guides or seals are a bit worn.

Any suggestions of things to look out for from those who have "been there, done that"?

Thanks in advance.

My posts are often verbose, so full credit to those who wade through them. :)
 

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Have you considered pulling the pistons out the rt side cover?
They may come out that way, but you will not be able to put them back in (piston rings need to be carefully compressed). On second thought the main bearing might not let all of the pistons out through the bottom.
 

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Enjoy The Ride
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I have yet to remove a head from the engine. I don't know if the head can be removed with the cam sprockets still attached to the chain. I'll bet Ernie knows.
 

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David Sheeley has done this job before , PM him.
 

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I pulled Steve Rowe's cylinder head on the "Dragon Fly". Did not remove radiators but did drain coolant. Pulled everything else as you listed.

Did not keep the cam gears on the chain as timing is fairly easy to re-do. I don't think they would have fit through the head opening that way. We did not have to though as a ring had fractured and scored the cylinder wall (it did fail the leak down test) and the engine was toast. Every piston on that 100 K engine had fractured ring lands.

Hope you find better conditions.
 

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there is no point leaving the sprockets in, as you have to rotate the crankshaft to undo the big ends, so timing is lost anyway, you will need to put the chain on last after you have put it back together, with the front cover off. it will all line up in the the end
 

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Questions right now: Should I zip tie the cam chain to the cam sprockets when removing the cam chain? Will that make reinstallation easier and reduce the risk that I'll get the valve timing wrong, or will that just increase the hassle?

I have rebuilt three engines now and have some pictures in my gallery as well as some threads about it somewhere on this forum. I wouldn't bother with saving the location of the cam chain and gears since you will have the entire timing cover removed and can start from scratch (follow the technique in the manual.

Should I do a "preemptive" change of the O2 sensor?

I wouldn't change it if you weren't having any trouble prior to the tear down.

I've done valve jobs on small engines, and lapped the valves on a couple of Airheads, but I think I'll send the K1200LT head out for a professional going through. Any idea who to send it to? I'm wondering if valve guides or seals are a bit worn.

With only 90k your guides are probably okay. The only way to tell for sure is to remove the springs and check the deflection in the clearance between the stem and guide. The factory and Clymer manuals is not clear about this. I built a valve keeper removal tool like the factory uses. I took the stripped heads to a machine shop and after inspection of a 200k and a 40k head showed what you'd expect. The 40k head was a successful lap job and the 200k is going to be rebuilt at another time. ;)

Any suggestions of things to look out for from those who have "been there, done that"?

I would follow the manual carefully and label parts in separate containers. Cleanliness is next to godliness. Don't rush it! Take your time and measure all clearances. Replace everything marginal (you don't want to have to go back in there do you?). Take a lot of pictures (you will need them).

My biggest suggestion though is to remove the engine and do a full rebuild. Not only will you get a full appreciation for the engine you will be confident that it will live another 10 plus years. Also the only way to service a "sprague clutch" is to remove the rear housing of the engine. It is a part that can easily be rebuilt with a relatively inexpensive part. Also when you buy your parts get a full gasket set. It has every seal and gasket you will need.


Seal and gasket set, engine 1 11001465300$344.91

My posts are often verbose, so full credit to those who wade through them. :)

I for one really appreciate your posts... no! really!

:D
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Pulling the head on the LT is not a hard job at all. With a service manual, anyone with good mechanical ability can do it.

I did put new valve seals on mine, but did not do a valve job, as the valves and seats looked almost like new.

I do have the BMW valve spring compressor for the brick engines, could loan it to you. It was the one for the earlier bricks, I made a couple parts for it so it would work on the later models.

 

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Discussion Starter #12
Gentlemen,
Thanks for all the replies, suggestions, and offers.

Good news: no broken piston lands.

Your thoughts please:
Number one plug and exhaust valves a nice tan color.

Cylinders 2,3,4 varying degrees of more crud on spark plugs, pistons, and valve faces.

Cylinder walls look good, cross hatching still present on all cylinder walls. Maybe I didn't break this engine in well enough; maybe switched to synthetic engine oil too early? But, she didn't burn oil for 70,000 miles or more. I never had to add oil between changes at 6,000 miles. Seems like one day it just started using oil, and seems like it has gotten worse with time.

What other causes of burning oil are there that don't show up on a compression or leak-down test? Valve guides, seals?

Right now I'm thinking I'll take out the valves, check the valve stems for "wobble" in the guides (not sure what the specs for that might be). If the valves are okay in the quides, I'll lap 'em put in new seals and button it back up.

Any thoughts?

Thanks in advance. :thumb:

Number 1:


In this view, Number 1 is on the right:


Number 1:


Number 4:


Number 4:
 

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Discussion Starter #13 (Edited)
An interesting observation: The big end of the connecting rod are fabricated in a way I've not seen before. They apparently cast the connecting rod, mill out the big end for the bearings, and then break the big end so it can be bolted onto the crankshaft.

All the other connecting rods I've seen were cut/machined. But the mating surfaces of the big end of these connecting rods are clearly fractured. (It does help keep track of how things were oriented because there is a clear fit up of the parts). :)

Is that common nowadays?
 

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I'm just curious. Did you put any of the rings back in and then mic the gap to see where you are there?
 

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Discussion Starter #15
I'm just curious. Did you put any of the rings back in and then mic the gap to see where you are there?
I have not removed the rings. Nor have I put a feel gauge between the rings and lands to check that gap if that's what you are referring to.
 

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Looks like the oil use progresses towards the rear of the engine.

Only thing I know of that commonly causes lots of oil use is a failed PCV valve. Since the LT doesn't have one of those, you would be looking for cracks in the PCV hose, manifold, or some other odd way for outside air to enter the system. That would pull oil mist into the intake system instead of it draining back into the crankcase. If your PCV hose is bad, that's likely all it would take. Might check all your intake for nests. Extra vacuum on the top side of the butterflies could have the same effect as a cracked hose.
 

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If the valve and seat contact area look good, I would not recommend "lapping". That is an old process, not really used any longer. About the only time I would use lapping compound is when the seats and valves have been ground, then just a touch of fine compound, with the valve rotated back and forth a couple of times to make sure the surfaces are making contact, NEVER enough to actually remove any metal to speak of.

When a valve is lapped very much, a little metal is removed. Then when the valve gets hot and the head expands, it seats on the "lip" of the unlapped surface. Not good.
 

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Discussion Starter #19
If the valve and seat contact area look good, I would not recommend "lapping". That is an old process, not really used any longer. About the only time I would use lapping compound is when the seats and valves have been ground, then just a touch of fine compound, with the valve rotated back and forth a couple of times to make sure the surfaces are making contact, NEVER enough to actually remove any metal to speak of.

When a valve is lapped very much, a little metal is removed. Then when the valve gets hot and the head expands, it seats on the "lip" of the unlapped surface. Not good.
Thanks for that info David.
 

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Discussion Starter #20
Looks like the oil use progresses towards the rear of the engine.

Only thing I know of that commonly causes lots of oil use is a failed PCV valve. Since the LT doesn't have one of those, you would be looking for cracks in the PCV hose, manifold, or some other odd way for outside air to enter the system. That would pull oil mist into the intake system instead of it draining back into the crankcase. If your PCV hose is bad, that's likely all it would take. Might check all your intake for nests. Extra vacuum on the top side of the butterflies could have the same effect as a cracked hose.
No nests or obstructions in the air intake. Air filter has 12K on it but doesn't look bad.
Crankcase vent tubing and manifold look okay.
Ports for the evaporative emmission system (charcoal cannister) are all connected to each other but not open to the outside anywhere. I did a cannister removal years ago and at that time I disconnected the solenoid valve that purged the cannister. Vacuum lines were disconnected from the solenoid valve. Those 4 vacuum ports are connected to each other but nothing else. No leaks evident there either.

I'll clean things up some more and look closer, but I don't think it is an air leak.
Maybe I should have searched for a leak with a little propane flowing around the throttle bodies; I didn't think of doing that 'til now.

Thanks for the ideas, keep 'em coming.
 
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