man the police around me would probably just b**** me out, even though i can still pedal the bike.
My first motor I didn't know what is was doing at all. It seized on me but it wasn't my fault. The first mods I did were just port matching and it made a great difference. I will have to add though that I really didn't see a difference it made till after I got a better air fiter to allow the port match to work. I know this cause I ran it with filter off before port match then again after port match. I can tell you that you don't have to be in rocket science to do it either. It is well worth the 30 to 60 min of grinding to have a smoother, better breathing china girl.(More Breath=more Power) And Of course we all know none of this matters with out being properly tuned that's a given.
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I have never ported anything, however i would love to feel that power you guys talk about. I'm not exactly sure how powerful mine is as i just got it and its my first motorized bike. However im pretty sure it can top out at around 35-40 cause i ride on the main roads, on the side walks and bike lanes of course, and almost can keep up with the cars haha and the speed limit is 45. I always have people riding next to me and giving me thumbs up. They're and I am suprised at how powerful it is i havent ported it though like i said. I'm pretty sure its AN 80CC-66CC Engine cause the jug looks bigger then most peoples. Can someone make and put up like a list of things to get ported and mess with inside the engine cause i really want to port it and take a look inside the block,not much of a block but still haha. However i wouldnt want to take it apart do something then want to take it apart to do something else you know i just wanna do everything once its taken apart with testing it in between of coarse.
Also I am in Mesa,Az i was just wondering if anyone in the area could help me port and tune the engine as I'm sixteen and my Dad says i shouldnt try porting anything from lack of experience. I dont know to much about engines but its really not hard to figure small engines like this out with a little common sense, that most kids at my school in my auto classes dont have haha. Also what are some tips about porting so that i dont destroy the structure of anything for example if i port, i mean when i port, my exhaust i plan on reinforcing how its affixed to the engine so it doesnt break things like that.
So just a quick scan of this thread but I really didn't see a link to this thread that may be helpful to noobs to port matching:
http://motorbicycling.com/f52/basics-port-polish-port-matching-16646.html
http://motorbicycling.com/f52/basics-port-polish-port-matching-16646.html
Make certain you have a full set of tools, and I mean FULL. it's not so much a step by step process as the kind of thing you learn the theory on, and extrapolate.
Right now my motor case is split and cleaned in front of me, with the case transfers ground out and patched with JBweld putty, repacked the 'sealed' bearings with super lube grease, the inside of the crank case has been textured with a high speed steel cutter, the crank has been balanced (Albeit barbarian style) the CDI is being replaced with a high RPM puch CDI, the head has been replaced with a puch high comp head, and the cylinder has been ported out somewhat, with proper piston skirt clearance at TDC. On the next motor I do, there will be a high performance walkthrough made up.
Right now my motor case is split and cleaned in front of me, with the case transfers ground out and patched with JBweld putty, repacked the 'sealed' bearings with super lube grease, the inside of the crank case has been textured with a high speed steel cutter, the crank has been balanced (Albeit barbarian style) the CDI is being replaced with a high RPM puch CDI, the head has been replaced with a puch high comp head, and the cylinder has been ported out somewhat, with proper piston skirt clearance at TDC. On the next motor I do, there will be a high performance walkthrough made up.
Great pep talk on improvement ! Are the specs all in the porting and tuning thread with how they should be set up with a degree wheel?
DTG is spot on comparing this to guitar tuning. It's a back and forth adjustment process... one thing changed always leads to other adjustments that must be made before you get the most from the first change. Then it sings!
LOL
I just had to laugh...
'this is not so much precision work as fixing the horrid work by the mfg'
lol
THAT, comes very close to truth of the matter!
I'm sure any amount of cleanup work done in these motors will be beneficial.
Even if done somewhat improperly it could increase the life of the motor, by preventing a bit of casting slag from dropping into the chamber at 4krpm.
Best
rc
DTG is spot on comparing this to guitar tuning. It's a back and forth adjustment process... one thing changed always leads to other adjustments that must be made before you get the most from the first change. Then it sings!
LOL
I just had to laugh...
'this is not so much precision work as fixing the horrid work by the mfg'
lol
THAT, comes very close to truth of the matter!
I'm sure any amount of cleanup work done in these motors will be beneficial.
Even if done somewhat improperly it could increase the life of the motor, by preventing a bit of casting slag from dropping into the chamber at 4krpm.
Best
rc
The last few guys are absolutely right.
My last motor build where I did the whole cha-cha runs sick! It was the best mod I did.
All the aftermarket parts help too. But the motor work I did. Pssssh. Forget about it! Basically. Port it all. These motors are gonna break in one way or another after about a 1000 miles. Enjoy it while it lasts.
That's if you wanna do 35+ consistently.
My last motor build where I did the whole cha-cha runs sick! It was the best mod I did.
All the aftermarket parts help too. But the motor work I did. Pssssh. Forget about it! Basically. Port it all. These motors are gonna break in one way or another after about a 1000 miles. Enjoy it while it lasts.
That's if you wanna do 35+ consistently.
hey Skarrd do you think the cut on piston from Jake's is worth buying? or would i be better off just trimming the skirt myself? is so, by how much?
If you have the tools, just do it yourself, its pretty easy. If not then buy the piston since a decent dremel might run you the same or more in the end
Gotcha, how would i know how much to cut off? I just want a little more top end, not too much so i dont lose much pressure or torque. thanks btw
And since every jug is different, isnt it really impossible for Jake's piston to have the same results with every motor
And since every jug is different, isnt it really impossible for Jake's piston to have the same results with every motor
Really, don't waste time porting these engines. lol you're making me laugh cuz you think you know what you're talking about when in fact you don't have a clue.There are big gains in porting these motors, everyone does it because it works..
Nice contradiction there. "Don't waste time porting these engines"
Followed by
"There are big gains in porting these motors"
Um... Wat???
the unported cylinder makes good torque for half the engine rpm if you have it tuned up good. yea 40 mph tops vibrating up a storm but will cruise nice at 25/30 mph all day, with that being said who da fuh wants that nonsense! 
Found a decent/not perfect $15 dollar ported cylinder on a shelf with 20 other ones to pick out of cleaned it up a bit and grinded up a piston and she has a power band now like it should and vibrations way down. Fun project! FYI those 415H chains the master links fall off so better to mod the chain and weld the pinsAttachments
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**** Yes, I agree with Bairdco 100%, so far I only matched my exhaust and intake and I've seen a pretty decent amount of response with my 120.00 China Girl.. They are cheap but also to have fun with & experiment....I've seen guys make some ridiculously silly mods with upgraded parts and they run like absolute sht..i said it earlier, match porting the intake and exhaust flanges will give you a big increase in performance. or at least, in drive-ability.
i've matched transfer ports, and cleaned up burrs on engines, but i haven't gone as far as trimming piston skirts, or other internal mods. i'm not afraid to, i just haven't had to. there's simple mods you can do, and you don't even have to finesse it with special tools. i mean, i use a dewalt cordless drill and some grinder bits for everything. i don't even trace out the amount of meat i have to grind off an intake anymore, i just go at it with the drill.
like DTG said, these ain't RC motors with high tolerances. they're 1900's technology, stolen by the russians, then copied by the chinese. it's an (at least) 3rd bastardized generation stump puller motor. and it's cheap. don't be afraid to experiment with it.
i build, ride, and race, the fastest 2 stroke china dolls around right now, and it really ain't that easy to make it go fast, last a long time, and exceed all your expectations.
and, for the record, the only major mods on my race bike is reversing the jug, so the carb's in front and the exhaust is out back,, then matching the ports, and "blueprinting" it all. i still have the NT carb and the stock exhaust. yeah, i tweaked everything a bit, but i lapped everyone at the deathrace with their shift kits, expansion chambers, etc...
and i'm just getting started. wait till the willow springs race...
The first thing you want to do is blue print the engine to the manufactures specifications.
Before you go out and buy expensive after market you must first know what you have to work with the only way to do this is to go through your stock motor and make sure everything lines up ports and to remove casting defects. You also want to make sure your engine is up to manufactures specifications before starting any modifications.