Wildguzzi.com
General Category => General Discussion => Topic started by: faffi on May 01, 2026, 03:02:33 AM
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I am enjoying re-reading old motorcycle magazines, I rediscover bikes as well as topics that are still relevant, and others that are not.
WARNING: This will not interest many, if any, of you.
In the February 1984 Cycle magazine issue, they ran a test on the RG250 Gamma. At 335 lbs / 152 kg wet, it was very light for its day. Especially considering it had triple disc brakes and a 3/4 fairing.
What caught my attention, was how different the power delivery was between the bike tested by Cycle and the one tested by MOTORRAD. Cycle tested a bike made for the Japanese market, while MOTORRAD one for Europe. I am not aware of any tuning differences, so the differences are either due to production tolerances, or physical changes. Both versions made a claimed 45 hp at the crank.
On the dyno, the Cycle bike made 30 hp at the rear wheel, the MRD bike made 41 at the crank, which should leave about 36 hp at the wheel. A significant difference. However, while Cycle's bike made more power as revs climbed, the MRD bike had a significant drop around 5500 rpm. For the comparison below, I am not directly comparing apples to apples, because the numbers from the Cycle edition is rwhp, those from MRD are crank horses. Still, the trend is obvious.
Listed Cycle - MOTORRAD numbers
5000 rpm: 9 - 12
5500 rpm: 10 - 10
6000 rpm: 12 - 18
6500 rpm: 15 - 23
7000 rpm: 20 - 28
7500 rpm: 24 - 33
8000 rpm: 26 - 36
8500 rpm: 28 - 41
9000 rpm: 30 - 38
9500 rpm: 24 - N/A (not measured above 9200 rpm, as it was all done by then)
Cycle never tested top speed, but MOTORRAD did. The gearing was too short for maximum top speed, as the bike managed 166 kph (103.15 mph) with the rider sitting normally, and 167 kph (103.77) with the rider prone at 9200 rpm. Two-up it managed 144 kph (89.5 mph). This is also the only test I have seen where MOTORRAD beat the 1/4-mile time set by an American magazine. Although by just a tenth, the 1/4-mile times set by American magazines were typically substantially quicker than those made by European rags.
Average fuel consumption for the test was listed as 35.7 mpg (6.6 l/100 km) by Cycle, and 32.6 (7.2 l/100 km) by MRD. This was typical of the time, mostly due to the 55 mph speed limit in USA compared to the no speed limit of Germany on their respective highways. Curiously, these days I find the tests made by US magazines tend to list consumption figures well above those seen in Europe, for whatever reason. While the consumption in Europe have gone from typically 30-35 mpg (CBX only gave 23 mpg!) to typically 45-50 mpg, figures from let's say Cycle World appears to have done exactly the opposite.
Cudos to the person(s) who managed to read it all :bow:
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Listed Cycle - MOTORRAD numbers - % difference
5000 rpm: 9 - 12 33
5500 rpm: 10 - 10 0
6000 rpm: 12 - 18 50
6500 rpm: 15 - 23 53
7000 rpm: 20 - 28 40
7500 rpm: 24 - 33 38
8000 rpm: 26 - 36 38
8500 rpm: 28 - 41 46
9000 rpm: 30 - 38 27
My new third column shows the percentage increases of the Motorrad figures over Cycle World's. Dropping the second row (for 5500 rpm), they average 41% (rounded).
Motorrad's second row value is called an outlier by statisticians. It it is so different from the overall pattern of the data that it is suspect of being a measurement error at the dynamometer or else a data recording or transcription error. A good analyst would investigate it before accepting it, even asking for the original data. (Some famous scientists have simply dropped outliers because they didn't fit the pattern.) I would guess it's a data error, in particular because taking it at face value implies a 50% jump in horsepower over only 500 rpm!
Dropping the second row makes both series seem plausible, with a slightly earlier power peak for Motorrad. Differences in the dynamometers may also be a factor.
Interesting post.
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I found two more tests in my archive, both in MOTORRAD. One was done in 1984, the other in 1985. 85 was the year the Gamma was updated.
Numbers listed 84 - 85
5000 rpm: 12 - 13
5500 rpm: 17 - 14
6000 rpm: 20 - 15
6500 rpm: 22 - 19
7000 rpm: 29 - 25
7500 rpm: 33 - 32
8000 rpm: 36 - 33
8500 rpm: 41 - 38
9000 rpm: 39 - 42
9500 rpm: N/A - 40
10000rpm: N/A- 35
So your theory that the 5500 rpm measure being an error in 1983 makes sense. Or the engine in the 1983 test had a fuelling issue at that rpm, as the test reported, because the engine could not pull itself through 5500 rpm in any of the taller gears. Whatever, the 1985 version pulled from 4000 rpm, 1000 sooner than the earlier version, then sacrificed the while midrange and then some for some additional overrev and slightly more top end, but a noticeably wider range close to its maximum power.
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I recall that the Japanese market RGs were in a lower state of tune. This was an issue when people brought them to the US, they required some fiddling to bring them up to full power spec.