my opinion on the china girl motor ..

I am a master automotive technician & also the only guy in the USA remapping software for saabs so I am a tuner as well...Jak Stoll Performance

I bought an engine from boygofast & yeah I taxed its ass pretty good but it was perticularly out of ballance
I ended up having the piston ring locator dowel come out & lock the cylinder up
when i got in there the main bearings were bad & teh lower rod was a tad loose
I put that back together in haste & found out that the case got dammages when the bearing
:ride2:http://motorbicycling.com/images/smilies/bicycle.gif
:ride:
:bike2:

so in about 3 weeks this engine was a total messhttp://motorbicycling.com/images/smilies/smile.gif
:)

as I understand it there are several supliers selling for many shops in china....
my understanding now is that its kinda a pig & a poke which only 2 guys I fealt were strait with me
I bought 2 upperends& had a bttom from five flags sent up & the rod was longer on the five flags bije they are trueley helpoful spookuyoonootth seem like a nice groupl of folk
I also saw the htatsdax & spoke with him he seemed like a cool cat
I just get the feeling that some of us get great engines & others get crappy ones & it would be cool to know who has the good ones
some of the dtuff cant be missmatched as there are subtle changes which force one to employ Mcgavern techniques fro engine buildiing
ambien is kicking in :nite nite
jak stoll
 
Last edited:

old motorbike

New Member
Sep 21, 2008
352
1
0
74
Fl.
Re: my opinion on the china girl ..

I'm a retired Master Tech also. I always wanted to build a motorized bike and opted for a cheap China deal. It wouldn't start for a day and Finally found that the plug was intermittent. I've only been riding it for about a week and not too far, just in case it decides to lock-up. Using 16:1 oil and running it for all it can do. I figured I'd try to get it to lesser oil mixtures before trying to recalibrating the carb or using another. It starts quicker and runs better than last week. Also I found out it's only a 70cc rather than the 80cc I wanted. It runs ok with quite a bit of vibration for a small engine. I'm also reading that some of the newer ones have roller rod and wrist pin bearings?? I want to install a shifter kit before I inspect the engines internals, If it runs that long? I seem to have a good one after reading some of these posts, but I'm still skeptical.
 

jburr36

Member
Jul 17, 2008
285
0
16
Idaho
Re: my opinion on the china girl ..

Mine is in a thousand little pieces on the floor at the moment. I just finished stripping off the paint with a chemical stripper and tomorrow I will degrease the parts. I tore it down since it had nearly 1000 miles on it just to see what wear there might be. Surprisingly there was little to none. The only issue I had so far that was a manufacturing failure is that the muffler came apart at a weld but that was an easy fix.

I guess I can say that I ran this engine pretty hard as well for I had it wide open throttle going 5 miles up a 10% grade and on the freeway. I would go out for 30 to 60 miles at a time on some days. It's a powerking 80cc motor.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
237
63
up north now
Re: my opinion on the china girl ..

I'm a retired Master Tech also. I always wanted to build a motorized bike and opted for a cheap China deal. It wouldn't start for a day and Finally found that the plug was intermittent. I've only been riding it for about a week and not too far, just in case it decides to lock-up. Using 16:1 oil and running it for all it can do. I figured I'd try to get it to lesser oil mixtures before trying to recalibrating the carb or using another. It starts quicker and runs better than last week. Also I found out it's only a 70cc rather than the 80cc I wanted. It runs ok with quite a bit of vibration for a small engine. I'm also reading that some of the newer ones have roller rod and wrist pin bearings?? I want to install a shifter kit before I inspect the engines internals, If it runs that long? I seem to have a good one after reading some of these posts, but I'm still skeptical.

I'd go to 24:1 now, then re-calibrate the fuel/air mix.
You will find these are all just under 70cc, none are 80's.

The ones with wrist pin needle bearings were sold for awhile, don't know how they turned out....the one (needle upper) I have (new) is supposed to be a 60cc.

I can say I have had engines from thatsdax, livefast, and another undetermined seller...they are all pretty much alike. You can get good ones and bad ones, the majority seem to be somewhere around the middle.
 

deacon

minor bike philosopher
Jan 15, 2008
8,117
3
0
north carolina
Re: my opinion on the china girl ..

I must have gotten the good one. I'm a master photographer so I was pretty much lost. I screwed up the install and had a master mechanic give me advice when I replaced the rings.

That is the only trouble I ever had except stuff falling off because I'm too lazy to check the torgue before I ride. I had a muffler almost fall off today.

A lot of the kit non engine parts were trash but not a big thing. It was easy to work around them.

Then again I'm old and don't expect my bike to be a motorcycle or a fine German car, it's just a hundred and fifty dollar motor on a thrift shop bike. All together less than a fancy road racer bike and I can out run him, on a good day.

I would never buy another one because now I build and ride alternative engine bikes.
 

velardejose

New Member
Sep 9, 2008
120
0
0
Lima, Peru
Re: my opinion on the china girl ..

Hi
I read in some seller site that they offer japan bearings as an option
That must be because of a good reason
I ruined a master bearing after my break in week, mechanic said it was a defective part
Thanks to the info in this forum my china girl runs perfect now
Jose