Sunday, April 17, 2011
Breaking a Beemer Boxer Myth
Many moons ago when I met Amber she had a '67 Bug and I had a '61 356 Porsche convertible. Every time I'm reminded about that car I feel like... ah, crying because it sure would be nice to have now. Shortly before we got married the Porsche had a valve burn out because it was adjusted too tight. At the time I didn't know anything about working on cars so I took it to the same independent shop that I use to take my '63 VW Bus for servicing. The problem was the shop wasn't real experience at working on Porsches. We didn't have the money to get the Porsche fixed and working on it myself was way too scary. It was something only professionals should do, or so I thought.
About a week before our wedding I had the Dunlop radials taken off the Porsche and put on Amber's Bug. That was probably a bad move because the night before our wedding we left her Bug parked outside our future apartment and it got stolen. The car was later found but had been converted into a dune buggy.
About three years later we bought a beautiful light blue '68 Bug for $800. After about a year the motor needed rebuilding and my independent shop wanted $700 to do the job. Not long before this we had bought our first house and our first daughter was an infant. We were strapped for money and spending $700 was out of the question.
It was because of this book I was able to rebuild that motor. It was my first and consequently a hugely rewarding experience. It opened my eyes in so many ways as to how a motor works. I felt I knew that car inside and out. The result was a far more gratifying driving experience. The myth was broken that only professionals can work on cars.
Now I'd like to break that myth for you on how difficult Beemer boxer engines are to service. Let's look inside.
The photo above shows the intake valves on the throttle side. They're hidden inside the two springs. We'll look at the adjusters in a minute. Look below the lower valve spring and you'll partially see a chain. This is the timing chain and has two markers on its gear that tell us when each piston is at "Top Dead Center" (TDC). We want the the piston in the ready-to-fire position at the upper most point (TDC). That way there will be lash or looseness between the end of the valves and the rocker arm adjusting nuts. In a position other than TDC those springs would be compressed and that would be a bad time to set the adjustment. The rectangular block barely visible to the left of the chain is our marker that tells us the piston on the clutch side of the bike is at TDC. I put the bike in 6th gear and bumped the back wheel with my hand in the direction it normally goes to get this marker in its position.
The photo above shows the throttle side of the bike. I have already bumped the rear wheel so the marker for this side is in its proper spot at TDC. This side is where our photos will come from. I've stuck the four feeler gauges in their respective spots to show where all the action happens. The exhaust valves are on the right and are adjusted to .30 mm clearance while the intakes on the left and will be set to .15 mm.
There is more to this but I don't want to risk your eyes glazing over and you dozing off at your computer. If your laptop isn't plugged in your battery will wear out and you'll wake up to a black screen. No, I've never done that. Although this might make a handy sleep-aid in the future so feel free to use it that way if you desire. There won't be any copyright infringement.
This is repeated on the intake valves but using the .15 mm feeler gauges. Once we get these two sets adjusted we're done. You now have the satisfaction of doing the job yourself, spending the afternoon bonding with and learning more about your bike, having the assurance that it's done properly, and saving a fair amount of cash. BMW club members have a wealth of information available on the forum online for doing all kinds of work. So if 6,000 mile services are keeping you from owning and enjoying a BMW Airhead, I'd like to expel that myth.
I can't think of another machine that gives the owner the reward of actually feeling and hearing the results of a tune-up like a motorcycle. Because we're straddling the motor and holding the handle bars we can sense when things are a little off or spot on. Doing your own work gives you an even greater awareness of how your machine is running.
It's been almost two years since I got the Beemer. She's due to have the brake system flushed so stay tuned for that job in the coming weeks.