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Scooterlabs Dyno

Project Description

dyno whole.jpg

This project is a scooter dyno for Scooterlabs Scooter Computer II scootute


  1. to have a rolling road to dial in carb jetting under load. Now the drought has broken it is increasingly the case that I have to wait to hit the road with clients scooters to test them. I am also sick to death of plug chopping. As are my neighbours.
  2. to have at least an inertia dyno to provide a consistent baseline for testing modifications as well as provide a central focus for the scooter tuning community (wild dog creek sc)
  3. provide a way to be a part of the vespa labs stable at the salt lake
  4. generate more income from scooter tuning (may as well be honest).
  5. be unique in being one of the few dyno facilities allowing 2-stroke O2 sensing

Next Steps

This section is to describe the technical details and processes involved in getting the scooterlabs Dynojet Dynamometer up and running after the Second Hand Dyno Acquisition


  • There is no computer whatsoever included with this Dyno
  • It appears that the computer is the only thing missing
  • The manual calls the roller rpm sensor 'optical'
  • The roller is an upgraded weight as the previous owner was using it for high HP Harleys
  • The computer patch lead is (disappointingly) not a 9 pin com port style indicating that it is the old type fom the dos system requiring a card on the motherboard (there goes the laptop idea).
    • Internetscooter: There are parallel port to usb adapters, though it can be tricky finding one that works, so buy one from a place that has a few and that you can take it back.
  • Two manuals were supplied by the seller. One is the original. In a proper folder and definitely DOS (I am a dosophibiac). The other is a bound printout and refers to a windows 98 /2000 version of the software. This would indicate that the windows software was used with this Dyno at some stage.
    • Internetscooter: I can scan and upload these if you want.
  • I have contacted the manufacturer with serial numbers so we can establish exactly what we have here.


  • uprated roller - probably of no benefit apart from the possibility that a run takes longer making independant o2 readings clearer
  • the unit has the optional disc brake installed. As two strokes do not respond well to a lot of engine braking this appears to be an important feature (with hindsight). Especially with the large roller.
  • The fan. I also was given a huge blower. This may not be necessary for scooters as they have their own fan system for cooling, but is a critical factor in using it for nearly all other vehicles. Blowing the exhaust away from the operator doesn't hurt also.

Specs dump

Is this from the manual Scootute?

standard roller - 395 kg, 45.72cm diameter, 50.8 width, 'modeled mass' 204 kg

high inertia roller (what we think we have) - 295kg

What is modeled mass and can it help up calculate the inertia value?

using the spreadsheet calculator, assuming mild steel , drum walls of 10mm and axle of 700mm long and 60mm diam, i interpolated the inner diameter of the drum to be 297mm making the total weight 395kg inertia 13.4437kg/m2 - Problem is this is the normal model. we dont have the weight for the high inertia, only 'modeled mass' - edit - turns out the inertia mass is stamped on the roller. drum roll please.... it is 13.67. Not a bad guesstimate.

one guess for the meaning of modeled mass would be the mass it would weigh if all the mass existed on the outside diameter of the roller. (impossible) It would make inertia calculations easier and would explain why the figure is lower than the actual weight.

If this is true, then could it be possible that there is a direct relationship between the modeled mass and the inertia factor (kg/m2).  Meaning as the modeled mass of the 'high inertia' roller is 1.44607 times the modeled mass of the standard roller, the inertia factor of our one could be 1.44607 times 13.4437  =  19.440