Rebuilding the China engine

E

Edward

Guest
#1
Anyone have a source for the small stuff like side crank bearings. I'm working on replacing the lower end bearing with a solid babbit bearing. I've used a 70's craftsman 7/8 deep well socket cut to size for a new crank pin. Disassembly of one of these motors is a straightforward job needing only 2 specialty tools, one being the gearpuller included with the kit and a hammer/screwdriver. Pulling the side bearings off the crank is looking to require a small gear puller. Eventually some aftermarket replacement parts will need to be found to keep these things alive.
 


bamabikeguy

Active Member
Joined
Sep 30, 2006
Messages
1,935
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1
#2
Edward,

the site is new, don't know if all the bells and whistles worked, whether you got my personal message, if not, will repeat.....

It appears there are plenty of guys with this info, contact TWalker, Cookie, itzbenz or ringal, they probably could answer your questions.

Me, I know less about engines than I do about bikes, I'm only along for the ride.
 

Tom

Active Member
Joined
Aug 4, 2006
Messages
1,095
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5
#3
It seems like some of the other guys should know, but I personally don't. I will probably have to figure that out at some point or another once my engine needs a rebuilld...
 

E

Edward

Guest
#4
The side bearings are made by SKF which is a mega international corporation. They are stamped France 6202-27/C2ELHT25. Now to find a retail source. The craftsmanship on these really contrasts with the rest of the motor.
I look forward to getting these and testing this modification out.
 


E

Edward

Guest
#6
The correct number may be 6202-2Z its written very small, the 6202-2RS is a double sealed version by Access Bearings, Inc. The moto mud guys seem to swear by double sealed bearings.
 

R

ringal

Guest
#7
6202 Bearings

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
 


E

Edward

Guest
#9
Well in the rush to get it together in the small amount of free time I have, I forgot to pick the inner seals off, so we'll see how it works out. The engine is quite tight, as in difficult to rotate. I'm turning it with a 14mm socket on the crankshaft and its starting to loosen up. I'm dousing it in 2 stroke oil quite often to help matters.
 


E

Edward

Guest
#11
Even with the 6202-2RS\C3 the case has developed stress fractures around the bearing seat when the bearing was pressed into the case. Mao's boys are a little off on their machining, there's hope for us yet, but the Kings motor is doomed to structural failure at some point. Never the less I will "endeavor to persevere" with the project. So a warning to those that follow the RBI Bearing U.S.A. 6202-2RS\C3 made in China requires additional enlarging of the bearing seat to properly fit. -Edward
 




E

Edward

Guest
#15
My bike was a vibratory experience on the 101 mile ride that I made last spring. My hands didn't stop aching and swelling for three days. I would still do it again but cross country? Not yet. Must be some other guy, with a suspension. :D
 


E

Edward

Guest
#17
Used a dremel cutter tool to deepen the bearing seats. Not a precision job but eyeballed it old school. The engine halves slid back together and now the rotating mass is actually rotating without difficulty. Most of the extra bits are on and I'm trying to get these damn woodruff keys to stay put while I get the gears on...grrr.
 

E

Edward

Guest
#18
Well its all together, now to wait for all this snow and ice to melt. I'll pull off the toasted 49cc from the trusty Stingray and put the original 80cc back on.
 

E

Edward

Guest
#19
The engine swap went so fast it was unreal, setting me up for the inevitable, try to start this thing at night with the temperature at a balmy 10 degrees. So I pedaled and pedaled until I was ready to hurl and fall off into the welcoming snow. What was I thinking? I need one of those starter machines like Burt Munroe. Well everything seems tight, at least at this temperature. I'll wait until warmer air wafts over the prairie before I try again, like maybe above freezing.-Edward
 



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