Recalibrage PZ30 pour l'altitude : Colombie
Client
An aftermarket distributor in Bogotá, Colombia
Secteur
Aftermarket Distribution
Indicateurs clés
Le Défi
Bogotá sits at 2,640 m, and much of the distributor's territory runs between 2,000 m and 3,200 m. Air density at that altitude is roughly 25% lower than at sea level, but the carburettors arriving from us were all jetted for sea-level use.
The symptom pattern was consistent: rich running above 2,200 m, black exhaust smoke, fouled plugs within a few hundred kilometres, and cold-start failures in the morning. Roughly one unit in five came back as a warranty return, and the workshop was spending more time cleaning plugs than selling parts.
The distributor had tried drilling jets locally. Because the modification was undocumented, nobody could tell a re-jetted unit from a stock one afterwards.
Notre Solution
We split the market into three density bands and calibrated a dedicated variant for each: 0–1,200 m, 1,200–2,200 m, and above 2,200 m.
- Jetting: main jet stepped from 92 to 88 and 85, pilot jet from 38 to 35, needle clip position raised one notch, air screw base setting shifted per band.
- Verification: every variant was run on a bench at simulated density altitude, not just at sea level, so the mid-throttle transition could be checked against the target lambda window.
- Identification: the float bowl is laser-marked with the band code, so a dealer cannot mix a high-altitude unit into a sea-level bike.
- Documentation: a Spanish-language jetting chart was packed in every carton, with the baseline settings and the correction steps for a further 1,000 m of altitude.
Le Résultat
Warranty returns on the PZ30 line fell 38% over the following two quarters. The workshop stopped re-jetting units by hand, and the distributor now orders in monthly batches of about 1,000 units, weighted toward the 1,200–2,200 m band.
The banding scheme was later reused for two other carburettor families in the same territory, and the jetting chart became the reference document the distributor hands to new dealers.
The problem with a single sea-level calibration
Carburettors are calibrated against air mass, not against altitude. A jet that delivers a correct mixture at sea level will deliver a mixture that is too rich as soon as the air thins out, because the pressure drop across the venturi pulls the same volume of fuel into a smaller mass of air.
In practice a customer never notices the theory — they notice that the bike smokes, the plug fouls, and the engine will not idle cold. In a market where the dealer is also the mechanic, that turns into warranty claims and lost trust, and eventually into a switch to a competing supplier.
How the three bands were defined
The bands were not chosen arbitrarily. We looked at where the distributor's customers actually ride: coastal and lowland routes below 1,200 m, the coffee-growing belt between 1,200 m and 2,200 m, and the high plateau above 2,200 m. Each band has its own typical density altitude range, and within a band a single calibration holds the mixture inside the target window across the normal ambient temperature swing.
Three variants were the minimum that kept the deviation acceptable. More bands would have improved the fit but would have made stock keeping unmanageable for a distributor working with limited shelf space.
What changed on the hardware
The castings are the same across all three variants — only the fuel circuits, the needle position and the markings differ. That was a deliberate decision: a shared casting keeps tooling cost flat and lets the distributor mix bands within one order without splitting the minimum order quantity.
Each variant carries its own part number and a laser-marked band code on the float bowl. The marking was the cheapest part of the project and the one that prevented the most errors.
What we would do differently
The first shipment shipped with an English-only chart, which the shop foreman translated by hand. Packaging the Spanish chart from the start would have saved two weeks of back-and-forth. It is now standard for any Spanish-speaking market.
Points forts du projet
- Méthodologie de développement agile
- Chef de projet dédié
- Support et maintenance 24/7
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