Posted: Sun Jun 18, 2006 12:51 pm
Where to start:
1) Observation on the tire pressure is good. The scoot's only meant to hold 180 lbs, so I'm guessing the specs guy that put in the tire pressure based it on that and it's 30 MPH top speed. Also, the primitive Spree suspension probably likes 20 PSI tires. Try running at 30 PSI to see if that helps.
2) I understand the reference to the HPV's in terms of gearing, but keep in mind that HPV's only have about 1/3 HP to work with, ever. Human powered, after all. You can get more power from the Spree plant, which was left at 2 - 2.5 HP for regulatory reasons. If you follow a HPV design, you'd create a Spree recumbent... and risk getting run over.
3) All mods you do to the pulley will be on the inner half. If you want to be more careful, you can re-space the inner half around with thin washers to maintain it's centerline.
4) As for the larger belt, I think that is done to keep from spreading the rear halves of the pulleys any more than necessary, although variator designs use this spring loading as part of the variable ratio drive.
5) Top things are pulley mods, cleaning up the intake casting, fire-cleaning the exhaust and deresticting, and increasing compression by taking .020" off the head on a lathe.
If you want to go beyond that, look at the exhaust and transfer ports inside the cylinder. If you measure them, either with a scale or degree wheel, you'll note that they're smaller than the listed port timings in the Honda manual. These could use cleaned up too. A slight raise of the exhaust port should help, and a light porting on the exhaust transition to the pipe to match.
Also, I've started to build expansion chambers, having finally broken down and bought a home welder. These work wonders on increasing top end power over the stock system. LMK if you're interested.
1) Observation on the tire pressure is good. The scoot's only meant to hold 180 lbs, so I'm guessing the specs guy that put in the tire pressure based it on that and it's 30 MPH top speed. Also, the primitive Spree suspension probably likes 20 PSI tires. Try running at 30 PSI to see if that helps.
2) I understand the reference to the HPV's in terms of gearing, but keep in mind that HPV's only have about 1/3 HP to work with, ever. Human powered, after all. You can get more power from the Spree plant, which was left at 2 - 2.5 HP for regulatory reasons. If you follow a HPV design, you'd create a Spree recumbent... and risk getting run over.
3) All mods you do to the pulley will be on the inner half. If you want to be more careful, you can re-space the inner half around with thin washers to maintain it's centerline.
4) As for the larger belt, I think that is done to keep from spreading the rear halves of the pulleys any more than necessary, although variator designs use this spring loading as part of the variable ratio drive.
5) Top things are pulley mods, cleaning up the intake casting, fire-cleaning the exhaust and deresticting, and increasing compression by taking .020" off the head on a lathe.
If you want to go beyond that, look at the exhaust and transfer ports inside the cylinder. If you measure them, either with a scale or degree wheel, you'll note that they're smaller than the listed port timings in the Honda manual. These could use cleaned up too. A slight raise of the exhaust port should help, and a light porting on the exhaust transition to the pipe to match.
Also, I've started to build expansion chambers, having finally broken down and bought a home welder. These work wonders on increasing top end power over the stock system. LMK if you're interested.