```
Horsepower = (Displacement in cc / 1,500) * (RPM / 5,252)
```
In this case, you have a 158cc engine. Let's assume you want to calculate the horsepower at 8,000 RPM. Plugging these values into the formula, we get:
```
Horsepower = (158 / 1,500) * (8,000 / 5,252) ≈ 18.59 hp
```
Therefore, a 158cc engine running at 8,000 RPM produces approximately 18.59 horsepower.