KLR650 Drive Chains 101

As you probably know, there are three drive chains in a KLR650 engine; one drives the
cams, one drives the balancer system/water pump, and the third drives the rear wheel.

The balancer and rear wheel drive chains are probably the most abused in
motorcycledom. Why you ask? The rear wheel drive chain, despite living in an
approximately 8” wheel travel environment, has no upper or lower chain control wheels (
there is a chain slipper on the bottom). MMP now sells the Top Gun Chain Master that
removes about 15mm of chain slack from the top run and protects the air box and its
bottom drain spout. Slack is a necessary evil that ensures the chain will not be too tight
when the chain is at its tightest (counter sprocket, swingarm pivot, and rear sprocket are
aligned), but uncontrolled, it can lead to early degradation of chain and sprockets.

Of the three dozen plus KLR650 engines that I’ve disassembled and studied, a vast
majority had excessively worn output shaft bearings ( the one behind the counter
sprocket). The reason is simple; most riders don’t know how to precisely adjust the rear
drive chain and often make it too tight, resulting in huge forces being transferred to the
chain and sprockets as the wheel passes through the tightest part of its arc. I’ve
developed a foolproof system for precisely adjusting drive chains on long travel
suspensions, but we’ll leave that for another time.

The balancer drive chain system on the KLR650 is even less understood than the one
driving the rear wheel. Why?

 

  1. It drives three sprockets and the crankshaft drive sprocket (total of 4).
  2. Until 2008, it had a frail adjustment lever (doohickey) that often failed.
  3. It had a poor quality adjustment spring that often broke.
  4. It provides no means of inspecting the condition of the spring without removing the
    dyno cover.

The most successful chain driven balancer system that ever resided inside a motorcycle
engine was probably in the Honda CB400/450 from 1978 through 1985 in various models.
I ran the doggie doo doo out of CB400/450 engines for well over 100,000 miles, learning
that chain driven balancer systems don’t need to be unreliable.

The Honda system once perfected in 1980 was successful for the following reasons:

 

  1. Like the KLR, the balancer chain was driven off the crankshaft, but had only two
    additional sprockets and two balancer weights in the middle of the engine.
  2. The balancer adjustment spring was totally reliable and didn’t over-tighten the chain.
  3. The adjustment lever (and shaft) were splined and much beefier even than the
    2008 KLR lever. It was locked by an 8mm nut torque to 18 ft-lbs.
  4. Built into the clutch cover was a threaded cap which, when removed, allowed
    inspection during the adjustment procedure.

If you want your KLR650 balancer system to be trouble free, you must: 1. Have a reliable
extension spring that doesn’t over tension the balancer chain (not a stiff torsion spring)
which could cause the splash-fed idler shaft and its needle bearing to fail, 2. Install an
inspection port to allow you to monitor the all-important balancer adjustment spring for
proper spacing between the coils (a coil-bound or closed spring will not pull), 3. A tough
2008 factory balancer adjustment lever (click here for why we prefer the 08 lever.).
Thanks to MMP, quality parts and instructions are available for those who wish to upgrade
their KLR650 balancer systems. Even the 2008 needs an inspection port and eventually,
a shorter extension spring.

The key to getting high mileage out of a KLR650 is to take good care of your drive chains
and sprockets.

Rod Morris’ 1996 KLR650, which is now at almost 50,000 miles, may get to 100,000 miles
with another balancer system upgrade at 75,000 miles (by then he will likely need new
balancer sprockets).

Keep in mind that drive chains that are too loose or too tight can accelerate wear of
bearings, chains, and sprockets. An overly tight rear drive chain can ruin the output shaft
bearing, and worn or improperly adjusted components in the balancer drive system can,
among other things, wear out the drive sprocket on the end of the crankshaft.

Replacement of the output shaft bearing and balancer/cam drive sprocket requires
complete engine disassembly. In the case of the balancer/cam drive sprocket in post-1995
engines, repair requires replacement of the left crank half. Avoiding all of these problems
is simple – just monitor, maintain, and adjust your drive systems. Also, be sure and do all
other maintenance and adjustments in a timely fashion. A properly set-up and cared for
KLR650 engine can go a long way, maybe even 100,000 miles. I hope yours is one of
them.

Thailand KLR650 Set-up

I’ve been saying consistently that if your KLR650 was produced in Thailand (including the
2008), you’d better go over it carefully from front to rear before going on any trips. The
Japanese KLRs were carelessly assembled, but those from Thailand are even worse.
It’s been six months since my 2005 KLR650 was totaled by a reckless teenager, so I
began looking for a used, pre-2008. I preferred a post-1996, low mileage Japanese bike,
but alas I couldn’t find such an animal. I did, however, find a 2004 with 2,010 miles on the
clock that had always been garaged. Since I’ve known the owner for more than 20 years, I
believed his story that all his non-running KLR650 needed was a replacement battery
since the current battery had died while sitting too long. I paid the money and trailered the ’
04 to my garage.

Once on the lift, I immediately went to the battery which was a near-new, service-free
Yuasa YTX. I couldn’t believe it had just up and died. The charger proved me correct by
bringing the battery back to full charge. Ah hum! The battery didn’t die; it was probably
run down by the starter.

I drained the float bowl and primed it with fresh fuel. The engine would not come alive and
finally had to be bump-started. Once running, the engine ran poorly due to an obviously
plugged-up pilot stage. I removed, cleaned, and reinstalled the carburetor after replacing
the neoprene parts and setting the float. The bike ran great immediately, but my work had
only begun.

To prevent this article from becoming a book, I’ll give you a brief rundown on what I found
and what I did.

Let’s start with engine set-up and maintenance. After draining engine oil and coolant, all
covers were removed and the following completed:

 

  • Adjusted valve clearance from .004” and .004” to .006” and .006” on intake, and
    from .005” (out of spec) and .006” to .009” and .009” on exhaust. KLR valves
    usually tighten early on and shops often don’t adjust them until they are out of spec
    (too much trouble).
  • On the left side, I installed a Wexman/Carl inspection port, 2008 adjustment lever,
    and an MMP spring of proper length (not too much pre-load).
  • On the right side, I inspected the mechanical and oil seals (OK) and cleaned the oil
    screen – which was half plugged with strings of case sealant.

Electrical work included installing an Iridium spark plug, manual fan switch, and carefully
detailing and insulating the wiring harness.

Chassis work included adjusting the steering (it was loose), spacing the front axle .010”,
and lubing all cross shafts with waterproof grease (swingarm pivot and Uni-Trak lever
pivot shafts were found corroded and difficult to remove). Suspension links came from the
factory backwards with the counter-sunk link on the wrong side (away from the chain).

Finally, some fasteners were upgraded and all were properly torqued.

The following defective parts installed by the factory had to be replaced:

 

  • Airbox (poor molding with large bubbles on the bottom).
  • Inner rear fender (another defective molding).
  • Coolant catch tank. Yet another poor molding with plugged bottom spout which
    wouldn’t pass fluid. Hard to believe, isn’t it?

I won’t go into detail on the upgrades except to say they included:

 

  • Front fork lowers hard anodized, dampers modified (forget cartridge emulators),
    progressive springs, and 8w suspension fluid at the correct level (these forks work
    great).
  • Rear shock replaced by Ohlins.
  • Modified stock bash plate to protect the bottom of the engine and it’s oil drain plug
  • Rear shock splash guard.
  • Top Gun Chain Master to control upper chain run.
  • De-tweeted muffler modification.
  • Splash guard for tail light wires.
  • Renthal fat bars and risers.
  • DR350 handlebar controls and hand guards.
  • Factory tank bag for light stuff.
  • Highly modified Chase Harper soft bags tied to Happy Trails side racks.
  • Custom triple-density foam, all-day seat complete with seat for Pauline.
  • Special foot pegs complete with right side stand attachments for chain adjustments
    and flat tire repairs.
  • MacDonald shift lever from MMP.
  • Low profile oil drain plug from “Dual Star.”
  • Rims, spokes, and nipples from Buchanan’s (1.85” rim).
  • Various lowering links for rake and trail changes.

All design and fabrication work not obtained from the aftermarket was done by me with
help mainly from Chuck MacDonald of MacDonald Products and Jeff Cole of C&J frames.
The week following completion of the set-up work, Pauline and I went on our first two-up
Baja ride since losing our 2005 KLR650 on September 2, 2007. We were rusty but had no
major problems on our one day, 251 mile trip, which included 50 miles of rain-rutted
roads. Two days later, I changed the rear shock and did 235 miles solo (75 miles of dirt).
I had almost forgotten in the intervening months without a KLR650, what a great bike it is
when properly set-up.

Stay tuned to Top Gun as we plan to present more information on the KLR and DR650.
For KLR650 guys, we are working on the ultimate cylinder and piston set-up which will
reduce vibration, limit oil consumption, extend engine life. We’ll attempt to prove that big
bores and cryogenics are not the answer for the single spark-plug KLR650.