Belts… Break’em in or break down. On my first ride last year, I put a brand new belt on my vintage Puma and immediately went screaming across the lake. Eager to detect any performance gain over the old belt, I did plenty of hole-shots and speed runs. Then decided to go for a leisurely trail ride. A mile or two into the woods, we were traveling at about 15 mph when I heard a clanking noise and the engine stopped dead! When I reached down and tried to pull the starter rope there was no movement. Images of broken pistons or other hard parts ran through my head. I was kind of relieved to find the mangled belt when I opened the hood. Better than a blown engine, I thought.
After chopping out the Kevlar strands from around the clutch and crank, I installed my spare belt and figured I’d be on my way. I figured wrong. When I started the engine it idled really high and I realized the Kevlar strands tore out the crank seal. And if that wasn’t enough, I noticed the clutch wobbling. Upon closer inspection I discovered a bent crankshaft! That Kevlar is like steel strands, it wrapped around that comet clutch and tightened up so much it twisted the crankshaft to a stop.
After removing the spark plug wire from the cylinder with the damaged seal, I limped it back to the truck on one cylinder. Removing the wire prevented the piston from burning down from running lean. I took a good look at the belt and noticed the outside casing was still in one piece. The strands between the outer case and the inner rubber cogs are what bond the belt together. The strands are actually one continuous looped cord and it had caught one end and unraveled at rpm speed. Strange I thought, a faulty belt maybe? Or should I have gradually broken the belt in at various speeds, in a more civil manner?
Riding season had just begun and there I was rummaging through my donor pile looking for a good engine. You can bet the new belt will be broken in properly this time.
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