Stretching a scooter like the Honda Ruckus and the Zuma 125 isn’t very hard to do. Actually, the harder question to answer is where the trend originated. The common answer is that it started with the big bikes and their extended swing arms. Hill Climb Dirt Bikes, with their crazy big engine, nitrous fed, insanity used a stretched swing arm to overcome gravity and make the bike more stable going uphill with all of that crazy power. If not, they would probably end up going backwards far more often than up the hill. It also came from the drag bikes, with their longer swing arms to also overcome the power of the engine from lifting up the front of the bike as much as possible to keep it going with full throttle blasts. What it is doing is reducing the anti-squat of the rear wheel by decreasing the angle between the horizontal plane and the swing arm. It’s like changing the pivot point on a seesaw; the longer the unloaded end of the lever, the easier it is for the unloaded end to move the loaded end.
Some guys then saw the drag bikes and though, “hey, that looks cool!” Thus more and more street bikes began to stretch their sing arms to reproduce that same look. They weren’t after the gains in straight line speed, but just how the bike looked. Of course what happens in the big bike world also happens in the scooter bike world. Someone saw that big bike with its stretch and though, “I want me scooter to look like that!” Soon, from those custom jobs came the first stretch kits and the rest is history. Currently, there are many, many manufacturers of stretch kits for your Honda Ruckus, Yamaha Zuma, and even swapped engines. They range from stretches that look cool to guys who are hardcore about their drag racing scooters. They even range from weld to bolt in kits as well as from a couple of inches to over 12 inch stretches!
While it doesn’t matter how the stretch is achieved, the way a stretch is achieved on a scooter is the same from scooter to scooter. Instead of buying a longer swing arm, which is not possible in most cases on scooters, the engine, CVT, and wheel are all relocated towards the rear of the bike. However, just like their big bike cousins, many of the effects of moving the axle back are there. The bike will have less of a tendency to wheelie, it will be stable from mid-turn to straight, and won’t like tight corners. So, if you’re looking for a nimble scooter, you’ll want to stay away from most stretches. However, for you guys looking to maximize straight line speed and need something to help keep the front of the bike down as you accelerate, stretching the bike is something you should be looking towards. If anything, after making an engine choice, the stretch should be towards the top of the list of needed parts.