6:34 PM 2/18/2004
DataMite Project Sec 1

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The system

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Performance Trends


Testing the Hyosung Comet GT250S

Fig 2.

What you get from this graph.

  • A) The rpm /speed, this can be easily made to show both MPH and KPH, helpful if the speedometer stops working later.MPH to KPH table.
  • B) You can by comparing the graph with the computed speed/rpm find out the error in the speedometer.
  • C) You can find safe shift points.
  • D) You can find that "Sweet Spot" for Cruising.
  • E) You will see just where you run out of steam.

One of the interesting things I found was the cutoff in 4th and 5th gear. The bike runs faster in 4th than it does in 5th, I think this was done for improved fuel mileage and or to met some speed limit requirements of the markets in some countries. This also may be a result of tuning to meet pollution requirements, but what ever; I do not need Overdrive on my bike.

Fig 2.

Having a set of larger Main Jets installed and running a new set of figures showed improvement in top speed and that I could now use 5th gear to advantage. Acceleration was also improved, but this is hard to document with out a good timing system.

We do have some Dynamotors in Korea, but no one here really is into Motorcycles, also a Dyno only tells you what the engine is doing, not what the bike is doing and any improvements in the bikes performance are dependent on the whole system. The Performance Trends DataMite I an ideal unit for use on a motorcycle, small in size and easy to install with good software and support, but like all on board computer systems needs to be calibrated to the vehicle.

Notice that I can now get just a little higher top speed in 5th compared to 4th with the big jets and a smaller front sprocket. The next step was the old tried and true, drill out the baffles in the exhaust, this did sound better and did show some improvement in RPM in 5th gear so them I put on an aftermarket muffler. Opening up the air box “de snorkeling” was next, this brought the engine up to red line in all gears, and it also showed a lot of error in the speedometer.

At this point I realized that I could not do 100 mph up an eight percent grade and could in no way do that kind of speed on the hill that I run, just all-short sections, then 180’ turns and 90’s to the top.

This base line graph or graphs now will let you see just what happened when you change something, like a new muffler or air filter. His sure is not the end of tuning, just the beginning, but this will let you get to close to the maxim MPH that the bike can do, great for a Bonneville run and you now have some very good information on shift points and speed.

The next step requires a Time relationship, so inter the onboard computer.

Section 1

 Prof. Charles M. Duecy B.A., M.A., TESOL, PCT.<p>
Jeju National University College of Marine Sciences
1 Ara-1-dong, Cheju-shi, Cheju-do  690-756 ; S. 


Prof. Charles M. Duecy B.A., M.A., TESOL, PCT.

Jeju National University College of Marine Sciences

1 Ara-1-dong, Cheju-shi, Cheju-do 690-756 ; S. Korea
a Studio 7 Production
a Studio 7 Production