The 1985 Yamaha VMax holds a unique place in motorcycle history, not just for its impressive performance, but also for its role in dyno calibration. Dynojet, a leading dynamometer manufacturer, used the legendary VMax to establish a baseline horsepower measurement for their chassis dynos. This article explores the story behind this crucial calibration choice and delves into the performance capabilities of the stock 1985 Vmax.
The VMax and the Dynojet Dilemma
In developing their chassis dynamometer, Dynojet faced a significant challenge: accurately calculating horsepower figures while accounting for the varying inertia of different vehicle configurations. Traditional physics formulas proved inadequate, consistently underestimating power output compared to accepted figures. After extensive research and experimentation, Dynojet founder Mark Dobeck made a pragmatic decision. He chose the most powerful motorcycle of the era, the 1985 Yamaha VMax, as the benchmark.
The VMax boasted a factory-advertised 145 horsepower, significantly higher than the 90 horsepower calculated using standard formulas. Aftermarket torque-cell engine dynamometers, meanwhile, measured the VMax’s output at around 120 horsepower. Dobeck instructed his engineers to adjust the Dynojet 100’s calculations to display 120 horsepower for a stock VMax. This decision established the VMax as the cornerstone of Dynojet’s calibration, forever linking its performance to power measurements across the automotive world.
Unlocking the Stock 1985 VMax’s Potential
Achieving optimal horsepower from a stock 1985 VMax requires meticulous tuning. A crucial factor is the float level setting within the carburetors. Setting the floats to 17mm, a slightly leaner adjustment, often yields improved performance. The VMax tends to perform well with a lean air-fuel ratio, ideally around 14.0:1.
anecdotal evidence suggests that stock 1985 VMax models often produced between 105 and 115 horsepower on a dynamometer. One owner reported a dyno reading of 115 horsepower for a completely stock, original 1985 VMax. Variations in factory settings, such as float levels, can contribute to these differences in measured horsepower. One mechanic noted that factory-set float levels were often found around 12mm, significantly richer than the optimal 17mm setting. Ensuring proper float levels, along with comprehensive tuning, can help unlock the true performance potential of the 1985 VMax.
