The Contact Patch
by Todd Vosper
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It’s that time of the month again, and did October ever fly by! I know some of you are
getting ready to put your bikes away for winter, and folks in the Southwest are getting ready
for desert season. Wherever you are, I hope you have a chance to get out and ride at least
a few more times before the weather turns.
Here are a couple of Internet topics that grabbed my attention this month:
Q. What is the best upgrade for the KLR-650 sub-frame bolts?
A. Your torque wrench! The sub-frame bolts supplied by Kawasaki are not the strongest
grade available. However, the real culprit in sub-frame bolt failures is the shearing moment
created when the bolts are allowed to loosen. You would have to try pretty hard to break
the sub-frame bolts even if left stock, provided you conscientiously kept them tightened to
specs*. Now, for a modest sum, you can upgrade to a higher quality and slightly longer bolt
for a little piece of mind. But again, they aren’t “fire and forget.” You still have to check them
from time to time. Why not work the sub-frame bolts into your normal chassis tightening
schedule that you periodically perform? You do tighten all of your fasteners every few
thousand miles… don’t you?? In all seriousness, use a little loctite (we recommend
intermediate Honda loctite), tighten the sub-frame bolts to spec, and check them
periodically. You won’t have any problems. Incidentally, if you install a Chain Master, your
lower left sub-frame bolt will already be upgraded. If you just can’t stand it, or you don’t trust
yourself to do a little routine maintenance, there is an aftermarket kit available that requires
you to drill through your frame, and then replace the two upper 8mm bolts with a single
10mm bolt that goes all the way through. I don’t doubt that this is a stronger solution than
two 8mm bolts, but it seems excessive to me. There are aftermarket upgrades to the four
8mm bolts for about $5, and the drill through method will set you back $50. As with many
things, the correct solution for you depends on piece of mind vs. maintenance time vs.
money. Remember though, if you opt for the drill through method, you still have two 8mm
bolts in the lower sub-frame that still need to be checked from time to time.
*Elden Carl has ridden KLR’s over 200,000 miles since 1990 including 40,000 off-road
miles on all kinds of surfaces. Pauline Read has been a co-rider on the bike for at least
15,000 of those miles. Fully loaded with gear and the two riders, his subframe carries a
load of nearly 375lbs. For the vast majority of those miles, Elden used stock bolts (with
intermediate loctite routinely torqued to spec) with no failures of any kind. (He somewhat
ashamedly admits that he replaced them with upgraded fasteners on his MSM KLR after
hearing all of the feedback about broken subframe bolts. His street KLR subframe bolts
Q. (This question was posed to us by Ward in Ohio and recently discussed on
Advrider.com as well.) What’s the story on DR-650 upper chain wheels breaking
off from the frame?
A. As I mentioned to Ward, neither Elden nor I have actually seen this on a DR-650.
However, when I asked some of the riders on Advrider.com, there were several folks who
owned or had seen DR-650’s with the upper chain wheel missing. Interestingly, only one of
about a half-dozen of these riders was actually the person who broke it off (he was riding
some very rough terrain and jumping his DR at the time); most had purchased a used DR-
650 which was already missing the wheel. In all cases, they reported that the threaded
metal boss on the frame broke completely off, leaving a dime-size hole.
Lacking first-hand knowledge, we headed out to the shop. One thing we noticed was that
the threaded metal boss is welded to the frame; it doesn’t go all the way through. This
installation method is probably easy and cheap, but it isn’t strong. All of the stress is now
focused on one weld, rather than being able to use the frame for strength (as in the case
where a bolt runs through both sides of the frame tube.) We had a bent 2005 DR-650
frame available and decided to test the strength of the weld. Try as we might using a large
set of pliers, we could only manage to bend the metal boss, not break it.
Some of the riders discussing this topic were of the mindset that it was no big deal; there
was nothing underneath to be damaged, and that it was a mistake to have a wheel on the
“pulling side” of the chain. If not for the research we conducted on our KLR-650 Chain
Master, I might be more likely to agree. Eliminating chain contact with other chassis
components is only one task a chain wheel is designed to perform. The chain wheel helps
guide the chain onto the counter sprocket and helps absorb chain slack, especially when
the throttle is off. There may not be any visible damage to the underside of the DR without
an upper chain roller, but it is definitely not “better” without one. Here again though, is one
of those situations where you need to evaluate your own riding style. If you have your DR
set up for the street or you don’t go off-road much – thereby avoiding the upper third of
suspension travel - you can probably get away without it.
Back to the question at hand; why are they breaking off? Without first-hand knowledge we
can only speculate. The metal boss on our 2005 frame was not going to break easily. It’s
possible that this is a problem that occurs on older bikes due to metal fatigue, lower quality
control on the welds of earlier models, or even a poor weld every so often that is unique to
a particular frame. Or as mentioned by the one rider who knew he had broken his, this
might be a problem that occurs during extreme off-road use, or heavy off-road use with a
heavy rider, or a heavy rider in rough terrain with an improperly modified suspension, or a
combination of everything mentioned, or… There are too many variables that could play
into this situation, and we won’t have better answers without more research. If we have any
trouble on our bikes with these upper chain wheels, we plan to install a boss that goes
through both sides of the frame with two welds. In the meantime, since we also think the
newer models may be stronger, we’ll stay stock. Additionally, we recommend staying away
from replacing the wheel with a larger diameter wheel. The larger the diameter, the earlier
and longer the chain will be in contact, imparting more stress on the boss. Finally, do what
you can to stay smooth on the throttle, particularly at or near full suspension compression.
You can be sure we’ll keep our eyes and ears open for more information on this subject.
We’d definitely appreciate hearing from you if you have any information that might be