Top Gun Motorcycles
Technical Insights
by Elden Carl
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Tale of Two Failed KLR650’s (Got an inspection hole?)

I always chuckle a bit when I hear stories on the Internet about the Kawasaki’s “bullet-
proof” KLR650. I have taken apart and studied more than 30 broken KLR engines in the
past 17 years; most of them the victims of the poorly engineered balancer system or of
faulty assembly at the factory. Pardon me if I’m a bit skeptical. In fact, if not for Sagebrush,
Eagle, and the Wexman/Carl inspection port, I would have hung up my KLR spurs years
ago. Thanks to Rod Morris at MMP and the beefy, new 2008 Kawasaki balancer
adjustment lever, KLR650 engine reliability is about to take a big step forward, but more
on that later. Let’s get on with the story.

About a year ago, Tore Bonanno was on the way south with some friends at San Quintin,
Baja, Mexico, when his engine died – permanently. Inspection revealed that a large
amount of coolant had entered the engine through a faulty oil seal behind the mechanical
seal. The resultant witches brew of oil and coolant took its toll on bearings causing the
engine to fail. The motorcycle, a 1988 KLR650 previously owned by the late Jake
Jakeman, was purchased as salvage by Rod Morris. Jake, as you may remember, was the
first person to come up with an improved, aftermarket balancer lever, among other
products. Since Jake was so well-known in the KLR650 world, Rod is thinking of trying to
resurrect the bike to original condition.

Now we turn to Jay Bass’ 2002 KLR650 with 37,000 miles on the clock. Not long ago we
had helped Jay fix his broken subframe which had fractured after the right upper,
aftermarket bolt had failed. Not long after, Jay’s bike was back on the road. He noticed the
oil in the sight glass looked grayish. Since he had replaced the mechanical seal just 6
months earlier, he was shocked that coolant had entered the engine through the oil seal –
just like Mr. Bonanno’s bike.

Jay went to a mechanic in his hometown of Lemon Grove (near San Diego) and had the
seal replaced again. A short time later, Jay’s bike stopped running about 25 miles from his
home when the right-side 6204 bearing (behind the balancer and water pump) failed. The
wobbly shaft damaged the oil seal again, allowing coolant to once more enter the engine.
Result – one dead engine needing rebuild, including all new bearings in the crankcases.
must be some way to get a better spring. A long and determined search finally paid off.
The spring manufacturer in question has a long history of making extension springs,
earning their reputation making springs for dirt bike headers (a very hot and unfriendly
environment for a spring) that wouldn’t break. They won’t give us all of their trade secrets,
but they did tell us that the extension spring must be made with the intended working
environment in mind. First of all, they will only use the best quality and type of wire for the
job. They also emphasized proper design – particularly in avoiding any sharp bends in the
spring. They stressed that a spring in this application needed to be strong but too much
preload was probably not desirable. This is particularly interesting since we’ve pointed out
the same concern in the past. The needle bearing on the idler shaft is relatively small and
too much preload on the spring leads to more force on the bearing, increasing the chance
of premature wear.  We are really looking forward to seeing the finished products.

Todd’s Note on Torsion Spring. As many of you know, there is a torsion spring offered
by the aftermarket to replace the factory extension spring. We would certainly like to hear
from riders who have installed these springs as the mileage on them accumulates. It may
turn out that this design is a successful alternative. We have several concerns about the
torsion spring. First, the torsion spring we purchased appears to be quite stiff, and
Kawasaki won’t tell us what the preload numbers should be with regard to the needle
bearing. Second, only with an extension spring can we monitor its preload and condition via
the inspection port.  Any spring has a chance of breaking, and we can’t see the torsion
spring. Even when Rod takes delivery of his new extension springs, and even though the
manufacturer has stated that “we’ll be astounded if you ever find one of our springs
broken,” we will still recommend installation of the inspection hole. The most dangerous
scenario regarding this balancer system is having a broken or missing spring, and
attempting to adjust the balancer chain. This will allow the system to go slack which will at
best result in a lot of metal-to-metal contact and noise and at worst, result in the chain
jumping off the sprocket resulting in a much-too-exciting end to your engine. Until we know
that the torsion spring exerts the proper pull and will not break, we’d rather use a high-
quality extension spring that we can monitor.
Idler shaft rotated to loosest point
of adjustment possible.
Broken spring inside engine case.
Screwdriver points to case
damage caused by loose balancer
chain.
This lever was in good condition;
but the spring can still get you!
There is a bright side to this story. When we
pulled the rotor cover and rotor from the left
side of the engine, we found the aftermarket
lever unbroken but the idler shaft had rotated
until the adjustment bolt was at the far
(loosest) end of the adjustment slot. Further
inspection revealed that the aftermarket
spring had broken. Since there was no
inspection port, the unsuspecting rider had
loosened the adjustment bolt, allowing the
weight of the chain to take the lever to the
loose end of the adjustment range. The
chain was so loose it was looping out and
deflecting off the crankcase behind the left
cylinder stud. (third picture from top)

Why is that the bright side to the story? Well,
if the engine hadn’t died “quietly” due to the
bearing failure, it would most likely suffered a
more violent end when the balancer chain
jumped track, stopped the engine, and
locked the rear wheel. Ask Kurt Grife, Jim
Bellach, Corby Hall, or any number of other
KLR riders who’ve experienced sudden,
catastrophic engine failure due to an
excessively loose balancer chain.

Which brings us back to a balancer system
failure with a happy ending, proving that the
Wexman/Carl inspection port can really save
your engine. Just ask our old friend Rod
Morris. Rod has an aftermarket lever and
spring installed in his 1996 KLR650. Prior to
adjusting his balancer chain recently, he
peered into his inspection hole. The spring
was not in view! Rod did NOT loosen his
balancer adjustment bolt, thereby avoiding a
potentially dangerous situation. Rod is still
riding, and will replace the spring with one of
his new, improved balancer adjustment
springs – discussed more below.

The springs are part of a balancer bullet-
proofing kit Rod is developing which will
include a new 2008 factory lever (call it
“beefy” if you must), Wexman/Carl inspection
port installation tool (very simple to use –
Todd notes that even a Marine can do it!),
two well-made extension springs, and an
inexpensive otoscope to light up and magnify
the spring during inspection. This same
inspection hole and otoscope allowed Rod to
notice his spring was missing. And once the
spring is replaced, it will allow him to monitor
the status of the balancer system, noting
when the adjustment spring has reached coil
bind and needs to be replaced with a shorter
spring. Like Rod and Jay, I have had a
broken adjustment spring as well, but like
Rod, I didn’t lose my engine.

We had previously noted that there is a very
similar extension spring INSIDE the DR650
engine that works the shift pawl. We can’t
imagine Suzuki using a failure-prone spring
in a location that would require a complete
engine tear-down to replace. Obviously, there
Maximum slack in balancer chain
Broken adjustment spring
Case damage from loose chain
Broken spring the culprit