West Coast CBX

"The CBX is the Vincent of the Future!" - Pete Ahrens


Dedicated to the preservation of the CBX Motorcycle


Autumn...leaves turning, ski sweaters and hot chocolate, park the scooter 'cause Old Man Winter on his way...

Wait a minute! He don't stop here! We never stop riding in California!

But you still gotta do your

CBX Homework

We've been reading a very informative and useful new book, The Racing Motorcycle, A technical guide for constructors, by John Bradley, Broadland Leisure Publications, 1996, available from Classic Motorbooks. Chapter Two is an enlightening discussion of engines and gearboxes. Here we follow some of Bradley's examples, crunching the power, gearing, road speed, and driving force numbers for the CBX. Where we had to pick one, we use the 1979 CBX horsepower numbers to compute the driving force gearing cascade diagram. Some things to look for in the driving force cascade diagram: wheelies and wheelspin are first gear phenomena, where the driving force can exceed the weight of bike and rider. The broad powerband of the CBX is clearly reflected in the long, flat force curves generated in the higher gears.

It is interesting to note that the 1979 CBX tachometer, setting redline at 9500, reads to 11000 RPM, but the 1980 and 1981 CBX tachometers indicate red line only to 10500 RPM, with 10 as the final numeration on the dial. According to Cycle, that 1500 RPM above 9000 represent a 6% horsepower dropoff for the 1980 CBX, and a 29% fall from peak torque at 6000 RPM.

Specifications are directly from the '79 Service Manual and '80 Addendum from Honda. Horsepower and Torque figures are drawn from the Cycle Magazine Tests, found in the Feb '78 (79 CBX) and Nov '79 (80 CBX) issues (and presented at Dave's Motorcycle Page).

Next assignment: Does cam timing explain the 1980 CBX horsepower reduction? We'll consult Phil Irving's Tuning for Speed and the classic Design and Tuning of Competition Engines.

James Elliot's Red CBX graces our Title, all the way from Ontario, Canada, where Old Man Winter has a beer and a shot on his way to Cleveland.

SpecificationsPri1st 2nd 3rd 4th 5th Rear
CBX Internal Gear Ratio
2.269
2.438
1.75
1.391
1.2
1.037
2.333
Overall Gear Ratio
12.9
9.3
7.4
6.4
5.5
Rolling Radius at Rear (Dunlop K591 130/80V18) = 13.3125 Inches


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1979 and 1980 CBX Horsepower and Torque


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Road Speed in MPH in Gear n at RPM

RPM Gear 1 Gear 2 Gear 3 Gear 4 Gear 5
2000
12.3
17.1
21.5
24.9
28.9
2500
15.3
21.4
26.9
31.2
36.1
3000
18.4
25.6
32.3
37.4
43.3
3500
21.5
29.9
37.6
43.6
50.5
4000
24.5
34.2
43.0
49.9
57.7
4500
27.6
38.5
48.4
56.1
64.9
5000
30.7
42.7
53.8
62.3
72.1
5500
33.7
47.0
59.2
68.6
79.3
6000
36.8
51.3
64.5
74.8
86.6
6500
39.9
55.6
69.9
81.0
93.8
7000
43.0
59.8
75.3
87.3
101.0
7500
46.0
64.1
80.7
93.5
108.2
8000
49.1
68.4
86.0
99.7
115.4
8500
52.2
72.7
91.4
106.0
122.6
9000
55.2
76.9
96.8
112.2
129.8
9500
58.3
81.2
102.2
118.4
137.1
10000
61.4
85.5
107.6
124.7
144.3
10500
64.4
89.8
112.9
130.9
151.5


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Available from Classic Motorbooks, 1-800-826-6600.

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*West Coast CBX Home*
*CBX Production Data*
*Index of Technical Information in the CBXPress*
*A Letter from the Master Himself, Shoichiro Irimajiri*
*Vintage Racing in the Streets of Steamboat Springs*
*EXTRA! Drunks and Bums Sighted!* *To Morro!*
*CBXtreaming!* *Death Valley Run*
*Is there a Next Generation Six in Your Future?*
*FAQ and Not So FAQ* *Coming Soon to West Coast CBX*



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