Honda TLR250R Javascript Gearing
Calculator
Default values are for a 1986 Honda TLR250R fitted with a new Pirelli MT43 recreational trials tyre and standard 14/43 gearing. I have tried a 40T option but that overgears, for the bike's power. By dropping the gearing to a 46T rear, it may be better for more extreme trail riding and Long Distance Trials (LDTs), but not conventional observed trials, unless geared down further.
Wheel diameter can vary
subject to tyre choice. Measure the rolling circumference of your tyre and use C=Pi times D to calculate the wheel diameter for this form,
where Pi is 22/7
Hold control key down and hit re-fresh in Internet Explorer browser to return the default values of this form.
MY TLR250R Dyno Run - Carried out on Fuchs BEI 251 dyno 2nd May 2000. Rear wheel data below.
CO measured at 5% to 5.6% across rev range which correlates to an
air/fuel ratio of 12.63 to 12.39 to 1, which is fine with 12 being about
ideal.
Revs P in HP and T in pounds ft
2.5 6 12.3
3 7.3 12.6
3.5 9 13.4
4 10.2 13
4.5 11.2 12.6
5 12 12.3
5.5 11.8 11.2
6 11.4 9.8
6.5 10 8
7 8 5.4
The figures indicates the nature of the beast with the torque curve flat for
virtually 3,000 RPM - all the way from just above tickover at 1,500 RPM.
The figures only start at 2,500 because it was tough to get a decent measurement
below that.
The power characteristics are all down to a long inlet, small carb, header
and soft cam etc, hence it does not breathe and rev out at higher RPM and
continue an upward path for torque/power. Mind you this graph certainly shows
useful power to the ground and consistent torque, so hence good traction which
together with a short wheelbase makes for much fun and an easy to ride motorcycle.
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