CHAIN ADJUSTMENT TECH: MR. KNOW-IT-ALL
Dear Mr. Know-It-All,
This seems like a ridiculous quandary, but here’s my problem. When I adjust my chain, I make sure I have the jam nuts real tight on both of the adjuster blocks. I put a screwdriver in the sprocket and run the chain backwards so the axle is snug against the adjuster blocks. Once I know the chain is perfectly lined up, I tighten the axle nut. The problem I’m having are the jam nuts on the axle blocks keep backing off. No matter how hard I crank on everything, it still manages to come loose. How do I keep things tight?
Mr. B, this is a common issue that has a myriad of hacks that people believe is the cure. I use an opposite tactic of adjusting the chain to the proper tension. Shove a screwdriver or rag between the sprocket and chain, and roll the wheel back until the chain tightens and the adjusters are taut in the block. Then, tighten the axle. Here’s where my technique differs from most: I leave the rear axle tight. I then back off the adjuster bolt, taking tension off the bolt, snug it back with slight tension, and then tighten the jam nuts. With this system, my chain-adjuster jam nuts remain in their proper setting.
CHAINED UP
Dear Mr. Know-It-All,
I recently installed a new chain and sprockets on my 2005 Honda 250F. I’m very proud of this machine and keep it buffed out—from the plastic to the stickers. I felt that in order to make the chain last longer, I would run the axle all the way forward so it has more room to stretch before I have to buy a new one. On my first ride after installing the new chain, everything felt different. The bike got super twitchy, the suspension felt harsh, and I had trouble controlling it even in the turns. I don’t understand how a new chain and sprockets can make my bike handle bad. The chain is an O-ring, and the rear sprocket is steel. Is the extra weight of the chain and sprocket screwing up my handling?
Curtis
Curtis, my friend, here’s some sage advice from a diligent person who has little regard for idiocy. Sticker placement over proper machine setup is the perfect storm—for a skateboarder. Here’s my evaluation of your drama: when you moved the rear-wheel position to the very front of the swingarm, this effectively hurt three key areas. It shortened your wheelbase, it stiffened the swingarm and effectively altered the leverage on the shock, reducing free sag. Always run the wheel in the middle of the adjustment zone, favoring more rearward as opposed to more forward. This maintains proper swingarm flex, proper leverage on the rear damper, and proper handling traits via a wheelbase that embraces stability and cornering bias.
I DON’T GET IT
Dear Mr. Know-It-All,
My buddy and I were talking about this article, and I’m trying to get my head around the concept. Do you mind explaining in more detail on what is really going on?
Thinking about it, I would think the larger diameter would take less force due to the larger area. Pressure is what moves the piston in the clutch: Pressure = Force/Area. Therefore, for the same pressure, a larger area would require less force and therefore less force on the lever from the rider.
Conversely, the smaller-diameter piston would require more lever movement to displace the same amount of fluid, giving more finesse to the control of the clutch (but would require more force as above).
Thoughts?
Jeff
Here’s my take: The smaller piston has to push less fluid, requiring less strength to move it through the hydraulic blood. These (9mm) systems work for the 250 four-strokes and the 250/300 two-strokes because they lack the horsepower and torque numbers of a 450. Those machines require the 10mm piston; otherwise, the clutch pull does not move enough fluid to maintain proper engagement. The bottom line: it works superbly on the 250/300 machines, providing a lighter pull and perfect engagement.
THE SORTING HAT
Dear Mr. Know-It-All,
I am a 12-year-old with a 2021 KX85 and I love it. It’s the best bike I’ve ever had, but now I am quickly outgrowing it. I can’t think of anyone else I would like to give me advice about what my next bike should be. Up until recently I would consider myself an intermediate-level rider with some racing experience. My skill level and confidence have improved a lot recently, and I am jumping most jumps at my local tracks and am “on the pipe” most of the time. I also do some trail riding with dirt bike buddies here in Florida, which is mostly flat, sandy terrain. Additionally, I enjoy learning to maintain my bike. I have always been Team Green, but now I know there are no two-stroke options for me with the exception of the KX112. My dad says he doesn’t think there is a big difference between my KX85 and the new KX112s—and, oh yeah, my dad says he will disown me if I develop a fondness for four-strokes. I am currently 5-foot-6 and 130 pounds, and would consider myself a little above average in the strength department. I definitely plan on continuing my amateur racing and hope someday it develops into a career, as well as a hobby.
My dad knows I am writing this to you, even though he says you’re an imposter and that the real Mr. Know-It-All met his demise via dehydration after throwing a chain during a clandestine ride at an undisclosed, now-defunct hare scramble. Dad says the modern Mr. Know-It-All column is far too nice to be the same sardonic and formidable Mr. Know-It-All that he grew up with. I believe in you, however, and can’t wait to hear your unrivaled advice concerning my new ride.
Zane
Even this dehydrated, drive-chain-hurling imposter can paint some advice onto a canvas that your father can appreciate. I, too, believe that making the switch to a 250F steed is a huge step considering your age and size. It’s much more appropriate that you segue to a 125cc two-stroke. The four-stroke 250 makes substantial torque and power, and much of that is from the midrange on up. It requires a heavy hand to control, the machine demands more care and feeding, and will eventually fit you like a proverbial tube sock. But, for now, my vote goes to the Yamaha YZ125. The power, mobility and competitiveness will make for a seamless transition from the KX85. And please, tell papa that if your passion does not wane, a four-stroke will eventually invade your world.
email: [email protected] | mail: Dirt Bike Mr. Know-It-All 25233 Anza Dr. Valencia, CA 91355
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