The Nitro 4 Tec has three drive belts that can stretch or become damaged over time due to normal wear. If left unadjusted the belts may start to skip over the drive pulleys, which can hinder performance and damage the belt's tooth profile. The rear belt tension is adjustable via belt tension cams in the right and left rear side plates. The rear belt in the Nitro 4-Tec transmits most of the engine's power. Because of the high loading on the rear belt, the tension should be checked every 3-4 hours (20-25 tanks of fuel) of running. If the rear belt can be deflected more than 0.25" (6mm), the belt tension cams should be rotated rearward to the next eccentric slot.
The Nitro 4-Tec's front and middle drive belts are designed to have a high initial tension. During the break-in period, the drive belts and pulleys will "wear in" and the belt tension will gradually decrease. Inserting shims under the front bearing block can tighten the front and middle belt tensions. Do not tighten the front belt tension unless there is more than 0.25" (6mm) deflection at the center of the belt. To tighten the belt, add the 0.1mm shim and retest. If the belt is still loose, remove the 0.1mm shim and add the 0.2mm shim and retest.
Electric 4-Tec belts must be replaced when they are worn or stretched.