It took us two days to get to Guanajuato because we were held up in Aguascalientes. No, not that kind of hold up. 

The kind of holdup every motorcyclist loves to run into. A fellow motorcycle enthusiast that can't get enough of your story. Duro spotted us on the 6 lane autopista (freeway) running straight into Aguascalientes. We stopped and chatted for a couple of minutes about our trip, and his interest in taking smaller motorcycle trips, and we were hoping he could point us in a good direction for some lunch. It was about three in the afternoon and we were both starving. 

He then noticed that we were burning oil on the right side exhaust pipes. I tried to explain to him that I was constantly watching the oil, and that I knew what the problem was, and that I was in the midst of resolving the issue. Which is our cam chain tensioner not holding tension and leaking a fair bit of oil past the seal. Well, instead of pointing us to a good restaurant for lunch, (we finally made it to the Birria market that I was dreaming of before we left the next day.)

The back of a lamb on the table in front of us. 

Pretty good Birria cook. 

Side note, Birria is a specialty of Northern Mexico where lamb, mutton and goats are raised. The best place to get Birria is in Aguascalientes, so stop right here.

Eat and watch your bike at the Juarez Market.

Back to the story, We got the Birria information later that night when we meet up with Duro and his wife, and got a tour of the city. But, the first place Duro took us to was the infamous motorcycle garage of the Maestro Jorge Venegas Estrada.

We discussed the issue with my motor, and he offered up a quick solution. drill out the old bolt on the cam chain tensioner so we could thread in a stud bolt. This was a good option, but I knew if we made one mistake Jen and I would be stuck in Aguascalientes for much longer than we wished to visit this uber modern city. Mind the Birria market. I chose to talk my way out of the situation, and I learned a good lesson.

Even if the mechanic you are talking to about a problem wants to do the work for free, it doesn't mean it is always the best decision. 

So to fill you in on why we decided to pass on the offer, I have found a used cam chain tensioner on eBay for seven bucks. This includes the cam chain and the guides. Not a bad deal.

So we get the tour of the town that night by Duro. Auguascalientes is one of the highlights on the Mexico bull fighting circuit. Some of the best bulls in the country are breed here and killed here. We also got to see a Marilyn Monroe impersonator, sorry no photos I forgot the camera, she was standing over a grate in a section of town that had the cars passing underground. When a car would pass underneath her, the viewers would get a little glimpse as she posed innocently for the photos.

The next day I got up early, to check the condition of the bike, oil, and cam chain tensioner. I had to add a bit of oil, but that was expected. We then took off for a visit to the National Museum of death.

Click on our pictures for more great photos from the Death Museum.

So here we are in Guanajuato. I again have the engine out, and I am getting the broken bolt on our cam chain tensioner fixed temporarily as our new tensioner gets shipped to us.

I am going to replace our original one, because I also want to replace our head gasket, the oil seal around the cam chain tensioner bolt, and put in a master link on the cam chain. Plus in the care package with these parts from the states will be a new electric starter motor for the bike. Lets hope all goes well. 

 Benjamin

Roadside Mechanics Series #3

That is right, what Jen said. "Hell Yeah Mexico!" 

So how did that happen. Two days ago we were fighting a broken starter, and xs500 still did not want to start right with the kick starter. Yes it was running well, when it was running, and did a great job on our test ride to Boca Chica, but it was not perfect. 

So, yesterday morning our baffling motorcycle problem of extremely hard cold starts, and a screeching noise that occured on while the engine was starting was finally exposed. 

I was recommended to perform a cold engine compression check by Vanya, an "old motorcycle" mechanic whiz on advrider.com. The procedure for the test is the same as in our earlier blog post for the Roadside Mechanics Series #1, except the test is performed while the engine is cold. The idea behind performing this check was that our hard cold starts were caused by a small air leak that can only be present when the engine is cold. Therefore, the air leak did not effect the operation of the motorcycle at normal operating temperatures because as metal heats up it expands thus closing off the air leak. 

So first thing I did at 7 am on the day we are supposed to leave for Monterrey, Mexico, was pull the gas tank, remove the plugs and setup the compression tester. Our initial results for both sides were very poor at 90psi and proved Vanya's point. We had a cold engine compression leak.

Vanya suggested that if this test resulted in poor compression, I should check that the eight head bolts were tightened to 25 ft-lbs. This is where I discovered our  problem! The head bolts were just loose enough that they did not created a good seal with the cylinders until the engine was warm. That is why the warm compression check didn't expose the problem with our compression.

Through this process I have learned that discovering the origins of a problem in a troubled engine requires following a series of steps to make sure that the three main systems of compression, spark, and fuel are opereating properly when you perform a tuneup, and that to check them in that order. First, make sure the engine has good compression. The main check should be when the engine is warm, but if your engine will not start then a cold engine compression test could expose the underlying problem of why the engine won't start. Then, and only then, should you proceed onto checking the electrical system to make sure that a healthy spark is being delivered through the spark plug, and that it is being delivered at the right time. From there you should go onto check the fuel flow. All of these ingredients combine to make up a running engine, but the first systems have to be functioning flawless make sure that you are diagnosing the true problem.

After I tightened the head bolts I got a healthy reading from both of our cylinders.

The motorcycle started right up when I put it back together, and is a breeze to start with the kick starter when warm, all of our gear is strapped on, and Jen is sitting on the back of the bike. Hurray!!!!!

Benjamin

p.s. Now I am going to go through the other systems and make sure they are functioning flawlessly with the correct compression. Just another step in maintaining a 1976 Yamaha xs500 in Jen and the Art of Motorcycle Maintenance.