China Doll woes

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highfuel90

New Member
May 1, 2012
24
0
0
bayville
Hey everyone, I just purchased my first china doll (although Id prefer a thai doll .xx.) And I have some concerns. It seems its 50/50 split on EVERYthing with this engine. Its the 80/66 cc kit. I knows theres variations of internals and all but id like to hear some answers.

Some people claim the engine implodes on them after 5 minutes of use. Do you think this is because of bad factory installation or user error in break in period?

I've read ALL of the posts about break in periods and 24:1 ratio bluh bluh bluh


Because of the variations in the engine, are they forged internals for upgrading one could do?

Im looking for a daily commuter but according to everything I read the engine will over heat from a short drive and eventually blow up.


I feel we need more structure in Identifying the internals and what can be done to make this "throw anyway engine" more reliable.

Thanks for everyones time!!!.bf.
 
Bikeguy Joe

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,837
252
63
up north now
They rarely if ever blow up in the first five minutes. You will know right off if you have an air leak, which is somewhat common, and will cause a lean condition, that could cause a "meltdown".

I have yet to ruin on and I have built several.
 
Al.Fisherman

Al.Fisherman

New Member
Sep 9, 2009
1,966
5
0
Calera, Alabama
highfuel90 said:
Hey everyone, I just purchased my first china doll (although Id prefer a thai doll .xx.) And I have some concerns. It seems its 50/50 split on EVERYthing with this engine. Its the 80/66 cc kit. I knows theres variations of internals and all but id like to hear some answers.

Some people claim the engine implodes on them after 5 minutes of use. Do you think this is because of bad factory installation or user error in break in period?
Don't know...Never had one implode (5 builds). I break in by running it about 30 min, let it cool and repeat for the first two tanks. I started with 16:1...never again. Go with at least 20:1, then up from there. I'm running 32:1, going to go to 50:1. Improper instillation can cause many different problems

I've read ALL of the posts about break in periods and 24:1 ratio bluh bluh bluh


Because of the variations in the engine, are they forged internals for upgrading one could do?

Im looking for a daily commuter but according to everything I read the engine will over heat from a short drive and eventually blow up.

Not true, if so it's not common.


I feel we need more structure in Identifying the internals and what can be done to make this "throw anyway engine" more reliable.

Thanks for everyones time!!!.bf.
Click to expand...
I have been running the same engine since 3/2009. This is what I do to all of my builds. I'm still running the OEM bearings, due to being lazy. When needed I'll change them out. I just hate to go through it right now.
https://docs.google.com/document/d/1GcesQihc7-mm3hJGf7UPiqOaRXZ8ekUT99QUZq2qXXE/edit
 
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H

highfuel90

New Member
May 1, 2012
24
0
0
bayville
Do you recommending anything before first initial start?

I know make sure head bolts/ all bolts down to spec via torque wrench. Should I open the head and lube the cylinder walls? Or see if the factory lubed the gears (I hear they said if doesn't need lubrication out of the box).

Thanks again!
 
Al.Fisherman

Al.Fisherman

New Member
Sep 9, 2009
1,966
5
0
Calera, Alabama
highfuel90 said:
Do you recommending anything before first initial start?

I know make sure head bolts/ all bolts down to spec via torque wrench. Should I open the head and lube the cylinder walls? Or see if the factory lubed the gears (I hear they said if doesn't need lubrication out of the box).

Thanks again!
Click to expand...
In short, read my Doc.
 
Al.Fisherman

Al.Fisherman

New Member
Sep 9, 2009
1,966
5
0
Calera, Alabama
:-||
highfuel90 said:
EDIT* I just read the attach document. Thank-you your information in MUCH appreciated! I know theres variation in the engines, but is there somewhere one could buy an upgraded piston bearing?
Click to expand...
Crank/clutch bearings....
6002 2RS (2RS= 2seals). remove the inside seal for the crankshaft

Wrist pin bearings
10X14X15 http://bearingsdirect.com/store/index.php?l=product_detail&p=3751 )2mm wider then below OEM)

10X14X13 http://www.motionindustries.com/motion3/jsp/mii/productSearch.jsp $4.91 or Sthil 028 bearing
 
rustycase

rustycase

Gutter Rider
May 26, 2011
2,746
5
0
Left coast
Four Stars for the Alf pre-build tear down and inspection routine.

Your chances of successful operation improve dramatically if followed. :)

In the least you will discover gaskets that do not come close to matching which will be digested by the new motor...

IMO
If I really wanted reliability, I'd go with a predator like some of the members are running now. They really are better.

Best
rc
 
Al.Fisherman

Al.Fisherman

New Member
Sep 9, 2009
1,966
5
0
Calera, Alabama
highfuel90 said:
EDIT* I just read the attach document. Thank-you your information in MUCH appreciated! I know theres variation in the engines, but is there somewhere one could buy an upgraded piston bearing?

Also, do you think the tensioner upgrade is worth it?http://www.ebay.com/itm/SPROCKET-AU...s=63&clkid=8110972955546288028#ht_1323wt_1290

Reminds me of tensioner on my timing belt in my honda.
Click to expand...
On Fleabay, there are two other tensioners that cost about the sane and are MUCH better.

http://motorbicycling.com/showthread.php?t=38913 (post #2) Mounts inside the cover.
OR
http://www.ebay.com/itm/230774323762?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649 Mounts outside the cover.
 
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