1. TARGET UPSHIFT RPM: For some noted models maximum vehicle speed (mph) is limited by throttle (drive-by-wire). The throttle will close/open to match the load and limit speed to the programmed maximum. RPM will decrease/increase accordingly. For example, if the vehicle has a windshield and cab and is loaded the throttle may remain fully open and the vehicle not reach the programmed maximum speed. If the vehicle has no windshield and cab and is lightly loaded the throttle will close to hold the vehicle at the programmed maximum speed. The DURACLUTCH will adjust to the throttle position and compensate accordingly.
Start with the weight guidelines for elevation. To check upshift RPM start from stationary and push the throttle wide open. Observe RPM at mid-speeds around 30, 50 and 60mph. You should be in the target upshift range.
Also observe the following: If the engine seems to be lugging try a lighter weight. If it seems to run at a higher RPM without “pulling” try a heavier weight.
2. TIRE SIZE: RANGERS and RZRS are geared in the drive train for the stock tire size to provide the full CVT ratio capability. Tire diameter directly affects overall gearing. For example on a RANGER 900XP with 25″ stock tires, changing to 30″ tires is the same as a 20% gear up. This will be like starting out in 2nd gear with a standard transmission car or pickup. Overall CVT ratio is compromised and cannot be recovered. This is true for any clutch/CVT. No clutch/CVT can compensate for a gear-up from larger tires unless there is an off-setting gear reduction in the drivetrain. This can be done by installing portal gear reductions at the wheels, gear changes within the transmission or a combination of both.
3. TIRE SIZE AND WEIGHT: Both tire size and weight determine rotating inertia which affects acceleration. The rotating inertia is increased directly by the weight or mass (2 x mass = 2 x inertia). Also, the rotating inertia is increased by the square of the radius of the mass from the center of rotation. Assuming the mass is concentrated at the outer diameter (a fair assumption), changing from a stock 25″ tire at 25 lbs to a 30″ tire at 50 lbs (real numbers) will increase the rotating inertia by almost 3 times (2×152/12.52 = 2.9). Add to these 4 tires and the rotating inertia increases by 10 times! This is a very large increase and greatly affects acceleration. Because of this inertia increase LO gear must be used much of the time even if gear reductions are installed. If LO gear is not used as required the clutch packs will wear prematurely. The warranty will be void.