Losing weight isn't just a perennial goal of human beings, it's the holy grail of motorcycle design, at least in terms of performance. If you want a motorcycle to accelerate quicker, stop faster, get better mileage or perform better in almost any area, just reduce the weight. Plastics have long been used for many reasons in vehicle design and weight reduction is certainly among them, so think about it, after removing the rider, where is the majority of the remaining weight in a motorcycle? It's the engine.
An interesting article in the New York Times talks about plastic auto engines, and they visit with Matti Holtzberg, an engineer and president of Polimotor (short for polymer motor) Research, who designed, built and even raced, plastic engines in the 1980s. He transformed a stock engine from a Ford Pinto, 88 hp and 415 pounds into a 300 hp, 152 pound engine.
... [he] used plastic for the block, piston skirts, connecting rods, oil pan and most of the cylinder head. Bore surfaces, piston crowns and combustion-chamber liners were iron or aluminum. The crankshaft and camshaft were standard metal components.
He raced a Lola in the IMSA Camel Lights series and had only one failure, a connecting rod from an outside supplier. Even with the success, interest from automakers was low, standard production and manufacturing techniques were working fine, why change?
Fast forward to 2009 and some companies are showing interest. Although iron engines in those days were heavy to start, plastic engines could even reduce the weight of today's aluminum engines by 30 percent. Technology has definitely advanced in the last 25 years so it seems natural to at least give it a try. Think about that sort of weight reduction on a motorcycle. In a car, the engine is a much smaller part of overall weight, on a motorcycle, it's the single heaviest piece.
Though other Polimotor engines were designed, no motorcycle applications were tried, from what I could find.
Polimotor attracted a lot of interest back in the 1980s, with articles in many publications but faded from the limelight. Now that there is a glimmer of interest, it's unlikely a motorcycle company would be in the position to take a chance on the technology just for its own use, but it might be the perfect place to test the technology for durability before using it in large scale application in the auto world. If it happened to work out, wouldn't it be neat if we got the benefit of some really lightweight powerplants in the process?
Link: New York Times