900 mile teardown report...

jburr36

Member
Jul 17, 2008
285
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16
Idaho
Ok. Summer's over and I want to be ready for next year. I hate surprises so I had an itch to see what kind of wear 900 miles did to these cheap engines to get a heads up on any problems that may arise. So I took my 80cc apart and stripped the paint and degreased all the parts. I repainted the parts that needed painted and closely inspected the critical parts.

Here's what I found.

* The cylinder has slight vertical scratches but it didn't affect performance.
* Lots of carbon build up. Removed carbon and all seems ok there.
* Bearings on clutch shaft had translucent grease...like vaseline or something. Also one had some metal flakes inside the bearing that gave it a gritty feel. I sprayed some WD-40 to clean it out and repacked both bearings. Seems okay now.
* The clutch plate and friction wheel has ball bearings that had no oil or grease. There are 3 holes that access the ball bearings in the back of the clutch plate. I shot some grease in there being careful not to put too much. The clutch pads won't work well with grease on them.
* at close inspection of the bottom of the cylinder I noticed a peice that look liked it was cracked however it is a casting problem (see pic). It hasn't been an issue so far so I'm not going to worry about it.
* Cylinder head has some real cashing issues. It looks like some severe cracking but it is bad cashing. No cracks, just looks ugly (see Pic).
* Piston looks absolutely fantastic for 900 miles after I cleaned the carbon off.
* Needle bearings look great and so do the main crankshaft bearings.
* Replacing all the screws and washers with stainless steel due to the climate here.
* Yes, That's why I painted my magneto green and the magneto rotor vivid purple.

Now it's time to reassemble the motor. I'm thinking of electroplating a new motor I might get instead of painting it.

Time to get to work.

P.S. That starter motor will work nicely once I maching the parts to make it fit. Will take some time for that though.
 

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old motorbike

New Member
Sep 21, 2008
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Fl.
Nice job and great pictures. It looks as though the Chinese are getting their casting a bit better than it was.
I wonder what can be done with porting for a little more power?
 

Cr9ck

New Member
Sep 7, 2008
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nice man let us know how it goes. Im really interested about your freewheel and electric / pull start.
 

Goat Herder

Gutter Rider
Apr 28, 2008
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N.M.
Acumma Mentadata [ from the cartoon] don't worry be happy its all good!By the way Bobby Mechfarren The song Don't Worry Be Happy he commited suiside, I still dig it your good man ride on me boy(^)its gonna be ok
 

Dan

Staff
Staff member
May 25, 2008
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Moosylvania
Don't think my last chinagurl looked that good when it was new. Nice job!

Acumma Mentadata [ from the cartoon] don't worry be happy its all good!By the way Bobby Mechfarren The song Don't Worry Be Happy he commited suiside, I still dig it your good man ride on me boy(^)its gonna be ok
Oh man, ya scared me! I had to research Bobby Mechfarren thing. (great song!) Turned out to be a rumor, Thankfully. snopes.com: Bobby McFerrin Suicide Rumor

Sorry. I ramble off topic again
 

amealnet

New Member
Sep 19, 2008
22
2
3
do you think a gas/oil mixture adjustment would improve engine wear? or maybe a sparkplug change would help?
 

jburr36

Member
Jul 17, 2008
285
0
16
Idaho
Depends on what you are adjusting it from or to and what type of plug you choose. I usually follow the oil manufacturer's instructions for the oil and I go for the forum member's recommendations for the plug. Their experience with the correct plug temperature is based on trial and error.

I was quite surprised to see how well my engine was lubricated when I tore it apart.