Engine Intake Info
- 'some late 85's, 86's and '87 SLE should be a flat reed engine (the flat reed engine came into play in late '85)
- If the engine and swing arm move with the suspension, it is a flat reed
- If the motor is rigidly attached to the frame it's piston port or pyramid reed
- the 81 SLE was pyramid reed
- Derbi RD's were pyramid reed
- Derbi Diablos and Lagunas piston port
- the Derbi DS50 scooter is flat reed
Technical Specs
Piston port engines
- cylinder inducted
- stroke: 43mm
- bore: 38mm
- displacement: 48.7cc
- compression 8.5:1
- direction of rotation: counter clockwise facing magneto
Download the repair manual for Derbi piston port motors here.
Pyramid reed engines
- Pyramid 3-reed valve, Crankcase mounted
- stroke: 43mm
- bore: 38mm
- displacement: 48.6cc
- compression 8.5:1
- direction of rotation: counter clockwise facing magneto.
Flat reed engines
- Crankcase 2-reed valve induction with triple transfer port distribution
- stroke: 40mm
- bore: 39.87mm
- displacement: 49cc
- compression: 10:1
- direction of rotation: clockwise facing magneto.
- Max engine RPM: 6500
- Flywheel nut is reverse thread
See a PDF file of the flat reed engine repair manual here.
Make a Water-Cooled Derbi
Please see this discussion from the forums.
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