An important Troubleshooting Lesson

[bull]

Recently had a 50cc Peace Sports in for a performance problem. It was described as an intermittent loss of speed and power with an occasional stalling that would not immediately restart.

A visual inspection did not reveal any problems. The scooter had been well maintained and had plenty of power. A short test ride revealed it was a hidden 63cc from the factory.

I test rode it for a couple days w/o any problem, good idling, plenty of acceleration, and cruise speeds acceptable for my weight. I decided to go on a long test ride (10 miles one way).

Everything was fine for about 6 miles, then I ran across some railroad tracks somewhat hard. Immediately noticed the scooter had lost top speed, and a rhythmic grinding noise was now audible. Top speed continued to decline and eventually the scooter shut off completely at a traffic light.

It would not restart, so I pushed into a C store parking area. Tried it a few more times and nothing. Waited about an hour, still nothing. Started walking it home. As I walked it, I could hear a strain from the rear wheel area accompanied by an intermittent grinding which both stopped after about 1 mile.

About halfway home, it started right up as if nothing had happened and I finished the ride home.

After it cooled down, I removed the CVT cover, looked and saw nothing. Removed the exhaust and rear tire. Noticed that it contained "metal dust" and then saw that 1 brake shoe spring was missing.

Removed the brake shoes, used a strong magnet to fish the metal dust out, and found a very tiny piece of the spring left hiding in a crevice. cleaned it all up, replaced the missing / damaged spring and reassembled.

Retest rode it, same course and everything was now fine. Noticed I had more top speed.

What must have been happening is the extra load when the spring piece became lodged between the shoes and drum caused the engine to overwork and overheat ending in a stalling.