2011 CBR250R Torque Specs

DannoXYZ said:

Greetings & Salutations!

I usually go off this chart:

Metric Bolts - Tightening Torques

Recommended thightening torque metric bolts.

www.engineeringtoolbox.com

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Tamir said:

In the service manual there is no information for the tightening torque of the three fuel tank screws. There is a tightening torque to the 6-Nuts that attach the fuel pump to the fuel tank: 12Nm
If you're going to take care of your motorcycle buy yourself the right literature, the Honda book, and the Haynes book, it's a worthwhile investment.

Torque wrench is nothing more than a nice toy for a mechanic who can afford a good set of a few of these according to the various tightening values. A torque wrench can not prevent a certain cases of over-tightening or under tightening, its handle is large and it does not allow the appropriate feeling that needed for stopping over tightening. A mechanical torque wrench is not an automatic tool, the requirement must be entered into it, and the requirements differ from screw to screw and the tightening of one screw in the torque of another screw will also end badly.
Additionally, the tightening torques for the same thread, say the very common M6 from our motorcycle, is affected by many factors:
1. Screw strength (Some screws have different strengths).
2. Diameter of screw head(With or without flange).
3. With or without lubrication.
4. Thread material (metal, aluminum, or plastic).
5. With or without thread-lock. And the strength of the adhesive, usually medium strength ("blue").
6. A worn screw or worn thread is easier to destroy.
The bottom line: Every beginner amateur mechanic should buy himself some screws and nuts and start to destroying them until he understands and mostly feels what is that "feeling" of true tightening value. you should learn to feel the flexibility of the metal, when to reach the stopping point, and not to use a lever that is too long which reduces the feeling.

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DannoXYZ said:

Well, it's been proven over and over again that expert pro mechanics will over-tighten small fasteners and under-tighten big bolts when going "by feel". Even after decades of experience they can't get better than +/-10%. We don't aim rockets "by eye", but rely on instruments with much, much more precision than our senses allow.

Beginners would learn "the feel" fastest with some sort of objective quantitative feedback. Clicker type wrenches aren't good for low-torque since they don't really click. They just kinda "clunk" and give and break gently. Newbies may miss this signal and continue to tighten. Personally I prefer to use beam-style wrenches or electronic torque meters with actual numbers for feedback.

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These are actually better for high-torque applications too. Such as head-bolts, main bearing-caps and axle-nuts which has issue with "torque creep" due to extra friction at high torques. When you reach desired torque, it will actually relax a bit and you can continue to turn and torque won't increase for several degrees. Keep on turning gently and finally... the needle will nudge up tiny bit.. ah done! Clicker type wrenches would have clicked when target torque is first reached, but will end up under-tightening.

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