23 December 2015

Back together again

Received a replacement clip for the timing chain master link yesterday and got everything installed.

I've heard a couple different styles of getting the fish clip on the master link. Snowbum says install at 2 o'clock on the cam sprocket, Matthew Parkhouse says he uses 10 o'clock. Personally, since I had the oil pan off anyway, I moved the chain where the masterlink is at about 7 o'clock, pretty much centered in front of one of the holes that go into the engine. Then I took needlenose pliers, lifted the clip into the hole area because it gives you way more room to work, hooked the center of the clip around the forward-most pin, then and let the clip hang (closed end of the pin must be at the front of the rotation with the open end trailing). Doing this in front of the hole makes gives you more room to work with the clip around the pins than trying to use tweezers or surgical tools and fitting between the crank case, obviously if the oil pan is still on the bike these holes should be plugged up and you won't be able to do it this way. Then I rotated the engine so the chain was at about 10 o'clock on the cam sprocket. Doing so allowed gravity to do the work of centering the fish clip right above the second pin. At this point all it took was a slight adjustment of position using a thin screwdriver, and then using that same screwdriver to press downward and get the clip over the pins. I've heard some people using magnetic screwdrivers to do the job, but I found that the magnetic tip was trying to pull the rearmost spacer off, so I switch to a non-magnetic, normal, thin screwdriver.

Today I got everything wrapped up and started the bike. It definitely idles/runs much quieter. Still need to dial in the timing, but since it's raining for the next week here, I'm in no rush.

19 December 2015

BMW Timing Chain con't

Finally got the parts I needed in from Germany. While inspecting the crank sprocket I decided that it didn't need to be replaced. The bike indicates approx. 44k miles and there wasn't a huge difference between the new part and old. That being said...

The tensioner was well worn. I didn't realize how dramatic it was going to be until I compared it with a new one. 

That tensioner was so shot that I decided to drop the oil pan and see if there were any plastic bits laying around, luckily there were none. Don't know where the pieces went since I only saw very, very tiny bits of pieces in my filter last oil change.

Before assembling the parts, I realized that the Iwis chain I got came with two E-clips instead of the older style fish clip. I've heard horror stories about the e-clips showing up in pans many miles down the road, so it looks like I'll be ordering the older style from Max BMW. Then it'll be time to get everything back together.

05 December 2015

BMW Timing Chain Inspection

The last oil change I did on the R90/6, I noticed some very small, black, plastic looking stuff inside the filter. I assumed this was from the timing chain tensioner as that's the only plastic coated component that could possibly make it into the engine, the timing chain did also appear to rattle and slap a little when the bike was at idle. I figured I'd turn the inspection into an Airhead Beemer Club tech day as the dis-assembly process and subsequent re-assembly is a little more advanced than typical Airhead maintenance. I ordered a new duplex timing chain, crank sprocket, and tensioner (and all the other bits like gaskets, washers, and tensioner spring) from Germany and they haven't arrived yet, so for now it's just the inspection.

Here's the process:

Remove the exhaust headers, I leave the mufflers in place. Some guys say to remove the front wheel and forks to give yourself more room to work, but I also leave them on. Set the left piston to TDC (that's the position the crank will be in for the entire process), and then loosen the rocker arms to remove the spring pressure from the right cylinder head against the camshaft, this will prevent it from rotating the cam while you're working. Next REMOVE THE BATTERY GROUND and only after this do you remove the front cover to access the charging and ignition systems. Failure to do so can result in a fried system from the cover shorting against the diode board. After disconnecting all the electrical connections on the alternator, remove the three mounting bolts on the alternator, and then remove it. To remove the alternator rotor, you'll need a special hardened bolt that threads into the crank and pulls the rotor from the tapered crank nose. Then remove the camshaft nut and remove the advance and points plate. Diode board is also pretty straightforward.

I thought I could get away without removing the starter cover and just use needlenose pliers to remove the wire going to the starter solenoid, but I wound up removing it anyway. That red wire on the bottom goes through the timing cover and connects to the diode board, obviously I took this pic after the diode board was already removed.

While removing the socket head screws and nuts, I managed to strip the head on the last one I had to remove. After about an hour spent drilling it out, I was finally ready to remove the timing cover and inspect the timing chain. To remove the cover you need to use a heat gun to heat up the cover around the crank nose where it's an interference fit against the bearing below it. After about 3-5 minutes of heating, lightly tap on the cover and remove it, it should come out very easily, if not then you need more heat. Once removed, this is what you'll see.

My timing chain had plenty of slack in it. Besides that, the chain tensioner was worn and missing pieces of the plastic coating (what was getting trapped in my oil filter, as seen in the pic below). If you plan on removing the chain for replacement, first remove the spring for the tensioner by removing the nut pictured at about 3 o'clock in the picture above. Next, remove the tensioner by removing the securing circlip and sliding it off its pin. Timing chain is removed by large bolt cutters (or a dremel if you're so equipped). Be sure to plug up all the holes that go into the case with rags so no metal can make its way down (I do this even before removing the circlip). Ensure you're still at TDC (OT "Obertotpunkt" on the flywheel). You can do this by, obviously, checking the inspection hole, and making sure the timing marks on the sprockets line up. The one for the cam should be directly above the keyway for the woodruff key (both should be pointing at 12 o'clock) and the one for the crank should be at 6 o'clock, lining up with the mark on the cam (woodruff key slot should be positioned at 9 o'clock).

I'm not sure I'll be replacing the crank sprocket and bearing just yet, the teeth appear to be in pretty good shape. Once the new one I ordered arrives I'll have to compare the teeth, if any wear is noted I'll just replace it so I don't have to go back in and do this again.