Valve Timing Help

[Sellis]

I neeed the wisdom of this borad! I removed my heads from my 1998 R1100RT and sent them to San Jose to be machined for dual plugs. I was a little boared this winter and wanted something new for the bike and this seemed like a good option. Now for the problem! I pulled the rubber plug, put the flywheel at TDC, used a drill bit to lock the engine, used a tie wrap to the cam sprocket to the chain, so it could not move on the timing chain, is short did everything I could think of so as not to get the timing off. Well, I removed the rockers, heads, ect. Once the rockers were removed, not thinking, I turned the cams, just to inspect the cam lobes. Then the light came on and I figured out I did not know which side of the engine was on the compression stroke, and even though the sprockets have a notch on them which matches the cam sprocket, and I have the sprocket tie wrapped to the chain, I could be off 180 degrees, on the valve timing. Ok, is there anyway to tell which side is on the compression stroke and ready to fire? I guess I can put it back togeter and pull the injectos and see which one squirts fuel, that will tell me which side should have an intake getting ready to open. I guess I would have a 50 50 chance of getting it right, but I thought I'd ask for the infinite wisdom of this board, what am I missing or what suggestions do you all have.

 

Thanks,

 

Steve

[smiller]

I guess I can put it back togeter and pull the injectos and see which one squirts fuel, that will tell me which side should have an intake getting ready to open.

Unfortunately that won't work, both injectors utilize a single output from the ECU and both fire at the same time.

 

Did you move the cams on both heads or only one? If the latter then you should be able to figure it out by looking at cam/sprocket orientation on the undisturbed head. And in the future... putting index marks on everything with an indelible pen prior to disassembly is an act you'll never regret...

[Stan Walker]

Both plugs fire at the same time (wasted spark). Both injectors open at the same time.

 

I think all you need to worry about is that the valve timing is 360 degrees out of phase between the two sides of the engine.

 

Stan

[Sellis]

Ok,

 

That helps, if my thinking is correct, then all I have to do is pick a side and make that the compression stroke and then make the other side the intake stroke. What do you think?

 

Steve

[Joe Frickin' Friday]

Ok, is there anyway to tell which side is on the compression stroke and ready to fire?

 

On this engine, it's determined entirely by the position of the cams. The computer only knows crank position, so it injects and sparks once per crank rev (twice per cam rev) at each head, and the position of the camshaft determines whether a particular head has a compressed/combustible mixture in the cylinder (TDC-before-ignition), or a bit of exhaust gas (TDC-before-intake).

 

Having said that, your engine in its current diassembled state has an indication of which side is which: the cam chain sprockets, which are still zip-tied to the chains. inspect each sprocket, and make a note of where the keyway is on each. Then go and look at the camshafts, and you should be able to determine the proper orientation of each.

 

one of the heads will end up so that the cam is on its base circle, i.e. you can freely spin it through most of a rev; this head will be at TDC-ignition when installed on the engine.

 

The other head will end up so that the cam is slightly holding all four valves open; this head will be at TDC-intake when installed on the engine. You won't be able to easily rotate the camshaft from this position. When you install this head, you may have to turn the crankshaft just a smidge to get the sprocket to line up with this camshaft. But don't turn the crank by more than a few degrees, or you're liable to damage the cam chain guides.

 

Let us know how it works out.

[Stan Walker]

There is a specified alignment of these camshafts parts relative to the alignment of the auxiliary shaft and crankshaft. This is set by referencing marks on the two sprockets for the timing chain. In short, you can be 360 degrees wrong according to BMW.

 

I just don't know that it really matters. Maybe you will find out and tell us?

 

Stan

[Ken H.]

I just don't know that it really matters.

I don't believe it does. Because both ignition timing and fuel delivery timing are not a factor in this engine, ISFA cylinder cycle, both have "wasted" pulses, it doesn't matter which side is the 'beginning' cycle so to speak.

[Flyer5]

Another suggestion is turn the engine slowly by hand for a few revs before hitting the starter button just in case . Dave

[Sellis]

Ok, I think I have enough info to get it back together in time, but I do want to make sure of one thing! The engine rotation when is running is clockwise when viewed from the front of the bike (or counter clockwise when sitting on the bike) Am I correct in this?

 

Thanks again for everyones help, it will be the middle of the week before I get a chance to work on it agian, I have a real job to pay for the toys, but I'll let everyone know how it goes!

 

Steve

[Stan Walker]

The engine rotation when is running is clockwise when viewed from the front of the bike (or counter clockwise when sitting on the bike) Am I correct in this?

 

That is correct, crankshaft rotation is CW when looking at the timing end of the engine (where the alternator belt is).

 

Stan

[Sellis]

Stan,

 

Thanks for confirming the rotation. In an earlier post you mentioned:

 

There is a specified alignment of these camshafts parts relative to the alignment of the auxiliary shaft and crankshaft. This is set by referencing marks on the two sprockets for the timing chain. In short, you can be 360 degrees wrong according to BMW.

 

I don't supose that you have anything that tells how to reference (or align) these marks on the sprockets, I remember that the arrows on both sprockets were horozontal when I took them off.

 

Thanks Again,

 

Steve

[Stan Walker]

I don't supose that you have anything that tells how to reference (or align) these marks on the sprockets

 

It's in the BMW service manual for the 1100's. Do you have it? or one of the other service manuals?

 

Stan

[Wild Bill]

I really think you are worried for nothing... As long as your wire ties don't get undone, and you don't move the crank you are OK... Spin the cams all you want... When they go back together they only align up with the sprockets one way!! That will set the cams... Then just look at the rockers to determine which head is on TDC.. (the head with the rocker that have some slack in both). If all you had done is the dual plugging, you will find there is little valve ajustment to do (assuming your valves were OK when you started and you did not mess with the adjusters..

 

Good luck!!

 

 

BK

[Sellis]

Stan,

 

No, I do not have a BMW service manual, I do have a Clymer, not sure if there is anything in it or not concerning timimg, It's at home, and I'm on the road traveling on business, I'll look at the Clymer when I get back home on Wednesday!

 

Steve

[Wild Bill]

I still don't understand why you are all worked up about this timing issue, Am I missing something? It sounds like you did all the wire ties correctly.

 

Just put it back together, then look at the rockers. One side will have both valves closed (the TDC side), the other one will have one or both valve springs partially depressed (the non-TDC side). Check the adjustment on the TDC side, after removing the wire ties and crank locking pin use the rear wheel to rotate and do the other side..

[Stan Walker]

No, I do not have a BMW service manual, I do have a Clymer, not sure if there is anything in it or not concerning timimg,

 

Having a Clymer manual is very much like not having a BMW manual at all.

 

When you get home look at section marked "Cylinder Head Installation" on page 96. When you get to the illustration labeled 30, turn your manual upside down as they printed it wrong (else why would the cam chains go upward?). Also step 15 is wrong! The final degree torque is 180 degrees done in two rounds of 90 degrees each (hey, they got it 1/2 right!!!!). Also step 16 doesn't mention loosening the nuts one at a time before doing the preliminary torque followed by the degree torque of 180. Lastly step 17 has you adjusting the rocker arm end play after the angle torque has been applied. This will be difficult as one of the head nuts you just torqued clamps the rocker arm assembly you need to move....

 

And that's just on two pages.

 

Stan

[Joe Frickin' Friday]

I really think you are worried for nothing... As long as your wire ties don't get undone, and you don't move the crank you are OK... Spin the cams all you want... When they go back together they only align up with the sprockets one way!!

 

Right, but assuming the engine/pistons are still at TDC, then one of the heads will need its cam positioned so that it's holding all four valves open just a hair. If it's not positioned this way before the rockers are installed, it can be a challenge to rotate it there without leverage.

 

 

...Now that I think about it, this really is a non-issue if the heads are installed and the cam chain sprockets bolted on the camshafts before the rockers are installed; that allows complete freedom of rotation of the camshafts to whatever position is needed so as to align them with their respective cam chain sprockets.

[bmwmick]

I sent you an email with a link but your email is invalid.

 

Mick

[Wild Bill]

That is right Mitch, that is what I was trying to say...

 

And additionally If he bolts the sprocket on to the cam first, he can torque it down after the cam assembly has been mounted..

 

BK