Rebuilding the China engine

[Edward]

Houston, we have lift off! Made it around the block and got it to idle. Can't do too much testing, as I haven't fab-ed the exhaust. The engine vibration is the same as when it had needle bearings, nothing too excessive but rougher than the 49cc. Babbit good so far.

 

[Cookie]

idea

Ed one of the guys on wone of the other sites uses an exercise stand made for street bikes to be used indorrs he got his from e bay you might want to try that

Cookie

 

[Edward]

Lol! Its the pedaling I'm trying to get away from, Munroe had this electric roller stand that rolled his rear tire up to speed before he engaged the clutch and started it. The engine being so damnably tight, the carb fritzing, and the ten degrees made the inital start an exercise in futility. It started today and had the whole neighborhood looking out windows. I welded a Suicycle exhaust diffuser on the end of the 4 inch pipe for tomorrows adventure, maybe this will make it quieter. or maybe not.

 

[Edward]

It vibrates to extremes, even for an 80. I'm going to tear her back down and have a look see, maybe I can suss out whats going on in there.

 

[tacoshell4]

so a starfire generation 2 takes a 6203?

 

[tacoshell4]

The 6202 bearing is a common bearing used in industry in small electric motors and easy to get hold of........ You can get the open no seals, screened with metal shields or sealed and greased for life...... When it comes time to change mine I would be using a sealed bearing and be removing the shield from one side of the bearing and having the bearing open to the crankcase so it is lubricated.... Leaving the screen on the other side gives you additional protection and acts as a backup shaft seal... I would stay away for bearings that use race cages with turned over metal tabs as shown in the picture as these tabs can snap off due to vibration and go through your engine damaging piston and liner.... The safer ones to use are rivited cages but they will have less balls in the bearing but still give good performance...... If the bearing is a tight fit on the shaft and in the case use a bearing with a C3 clearance....
Regards Al

Just my 2 cents. if you leave the outer seal on the bearing the outside mainseal wont get lubed by the fuel oil mixture thus runnig dry and more prone to fail.