Cracking a Case

Story by Costa Mouzouris//
March 1 2018

By digging a little deeper, a potential major problem was uncovered.

About this time last year, I purchased a used 2008 Kawasaki KLR650, primarily because I wanted to keep its wheels as spares for my KLR. I paid a paltry amount for that otherwise pristine motorcycle because it consumed oil and the owner had run it dry and seized the engine. Like that bike, my 2008 model uses oil; it’s an unfortunate trait of that model year due to the use of new, friction-reducing piston rings. (Kawasaki fixed this issue the following year.) But if you check the oil regularly, as I do, you’ll never run into any problems.

Despite this, I decided this year to rid my KLR of its thirst for oil by refreshing the top end. But replacing a set of rings alone wasn’t justifiable for the amount of work involved, so my trusty KLR would also get an oversized, high compression piston – why not boost output a bit while I’m at it? The piston came from German piston maker Wossner, based on a recommendation by my friend and shop owner Bryan Herbert, who, among other things, specializes in KLR650s.

With piston, re-bored cylinder and gasket kit in hand, I also decided to dig deeper into the engine and split the crankcase to give the entire engine a once-over, even though the bike has only 27,000 km on the clock. It’s a good thing I did so, too, because upon closer inspection, I discovered what looked like a crack inside the left case that ran between the main bearing and the rear counterbalancer bearing. The crankcase has several casting marks that look like cracks, so to verify if this was indeed a crack, I cleaned and dried the surface and heated the case, which would cause any oil that had seeped into the crack to work its way to the surface, thus confirming a crack. It did. Further investigation revealed that the crankcase seemed unusually porous, and the crack actually transferred from the crankshaft side of the crankcase to the alternator side, leaching oil through the porous casting marks.

This caught me by surprise, since the engine had never been taken apart before, so it seemed to be something that happened either at the factory upon assembly or over time due to something stressing the crankcase.

Now, this had never caused me any problems, as it was within the crankcase with no possibility of any oil seeping out of the engine, and being that the crack began and ended in a bearing bore, it was unlikely to travel any farther. Although I could have reassembled my engine as it was, the crack did weaken the crankcase, but more importantly, I have a tendency to home in on mechanical issues and focus on them while I ride, so even though that crack would be unseen and unheard while riding, it would have left a mark on my psyche and eventually driven me crazy.

The solution was to replace the crankcase (unfortunately, I had had a spare set when I owned that used KLR, but I sold that engine last winter). Curiously, while searching for a set of crankcases online, I found several right-hand cases but very few left ones. Ideally I wanted a complete set, and finally found a nearly new crankcase set from a U.S. recycler on eBay, advertised with 1,300 miles, for just $200. The only difference between the new and old crankcase was that the new one came from a 2014 model, so it was black instead of grey like mine – and it had no cracks.

This all happened during the holiday season, so I couldn’t contact anyone at Canadian Kawasaki Motors to see whether this was a recurring issue. However, I did contact a former long-time employee who used to work in the warranty department, and he told me that he was not aware of any such problem with the KLR650. He did advise me to check the balancer chain regularly, which I’d already been doing. This item rarely receives attention and can cause severe engine damage if it gets too loose. If you’re a KLR owner, check the balancer chain at every oil change; it’s easier to do than the actual oil change. All you need to do is remove a protective rubber plug located at the bottom left-hand side of the engine behind the lower frame tube, loosen the bolt behind the plug to free the spring-loaded tensioner, then retighten the bolt.

My engine is now completely assembled and waiting to be put back into the frame. Before doing so, though, I’m going to take advantage of the easy access to the rear suspension to service all the bearings. Once all that’s done, the only thing left is to wait for spring and take my freshly rebuilt, crack-free KLR for a ride.

Technical articles are written purely as reference only and your motorcycle may require different procedures. You should be mechanically inclined to carry out your own maintenance and we recommend you contact your mechanic prior to performing any type of work on your bike.


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