300 $ to blow on a china girl motorized bicycle.....

ok i have 300$ to blow on a china girl, the 4 stroke trike is off... well the trike is on but my dad brought up a good point on the legality of a 212cc 4 banger custom trike .... if its going to happen its going to happen to me lol he said how would you like to get done building this thing and drive by a cop reving a 200 pluss cc 4 stroke strait piped that sounds like a harley with no plates and have it confiscated and go to court ? i said ummmmmm .... lol and its not like the china girl where you can not tell the diff between a grubee gt2 50cc and a dax f80 70cc motor, a lot of people know what a 6 horse 200cc motor looks like and most cops will see it in a second and know its not 50cc.

so i am taking the 300$ i have left from my trike fund for motor hop ups for the preddy and dumping it into a rock solid china girl.

option 1

-keep the bottom end from my grubee gt5 66cc 0$
-keep the 70cc puch high high head 0$
-get the arrow 3rd transfer port grubee jug and reed valve kit with dellorto carb 190$
-dax rt dellorto carb cable 20$
-titainium wrist pin 12$
-grubee gt5 piston 10$
- custom x chamber pipe for wide power band racing 0$


cut and mod piston skirt for optimum reed valve preformance and ramp piston dome
deck arrow grubee jug for correct squish band clearance with puch head
some custom paint VHT high heat .

tottal cost 220$
this would use my grubee bottom end (not balanced, but close as is and with 2,500 miles on it) and i would end up with a gt5 arrow street racer, basicaly an unbalanced version of there 4.5hp race motor useing the puch head instead of the fred head, will net the same compression though, only it would have a wider squish band for a lil more midrange less top end and a lil less over all rpm's

option 2

-dax balanced motor 70cc 120$
-puch head 0$
-15.75mm stage 3 walbro carb carb kit 125$
- titainium wrist pin 12$
-custom made exhaust 0$

tottal cost 257$

ok this would be one bad larry of a piston port motor especialy with the 16mm walbro butterfly carb ! i am shure with a light wrist pin and cut modded piston and a full port and polish and the throttle responce of a butterfly carb i would be looking a a real quick reving, high rpm motor right in the ballpark preformance range of the arrow option.

i would ramp piston and cut skirt
port and polish the jug mabey add a 3rd transfer port or run open transfers
deck the jug for optimum squish with puch head


will be run to a live rear axle with 2 26in rear tires and a 40t rear sprocket


what would you guys recomend if you had a 300$ limit to build a china girl but already own a grubee gt5 bottom end ? dump it and start new or use it and go all out ?

Re: 300 $ to blow on a china girl.....

maniac57 said:

I'd go with the Dax (or similar)balanced bottom and port the top end for a nice wide powerband. That's my plan for the new balanced bullet I recently ordered from motorbicycleracing.
Keep the revs down without sacrificing rideablility.

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yes i have heard that motorbicycleracing has balanced motors, are they the same 69/70cc balanced motors as the dax ? whats the cost ? and how does one go about getting one ?

my grubbe gt5 does not vibe that much believe it or not i have had it up to 9,300 rpms trying to blow it and she just wont quit lol it only has 2,500 miles on it and she runs smooth, i got real lucky with this one .



then again ..... i know the 212 preddy will get impounded right off the bat the cops around here are not stupid and know there stuff about moped laws, i have been stopped 3 times and asked about the motor, i say its a 50 cc bike motor kit and they say cool and let me go, i know if it was a honda gx or a brigs 5 hrs it would have been taken !
but the preddy 79cc stripped down mounted vertical looks like a large 50cc and i could probably get away with it if i slapped some 50cc generic stickers on it

would the 79cc preddy be worth it and powerfull enough if i have the stock cam shaft sent out and rewelded and ground for higher liftand good duration, also i have valve cutting tools for a 3-5 angle valve job, it will also be degoverned, and a custom intake manifold and atv carb would be added and the head would be decked for 10.5:1 comp. so preformance mods are open to me with this motor. i know what i am doing with 4 stroke valve train. i am just wondering if a 79cc 4 banger will be enough for a trike if its a single speed ?

i can get the preddy 79cc and a torque a verter and mod it all for around 300$ also

Re: 300 $ to blow on a china girl.....

what carb and intake would be best to use for all out power ?

options for carbs

1 the dax rt or dellorto 14mm
2 the walbro 15.75 stg 3
3 cns v3 16mm
4 the mikuni vm18mm
5 dellorto phgb 19mm

inatake options

1 billit intake
2 jnm hogsnout
3 freds power plenum intake
4 rse reed block
5 arrow reed block

i own 2 21mm kien carbs from a 3 wheeler and a 27mm mikuni with acselerator pump and can make custom intakes but i think the carbs are to large and they are primaraly for 4 smokes plus i want to keep it simple so the least fabrication poss is what i am after unless funds and preformance call for it

i am open to other carb intake options also plz let me know what you think

Re: 300 $ to blow on a china girl.....

maniac57 said:

Calm down roger....take two turbo hayabusa motors and call me in the morning.

Click to expand...

lol this is what happens when you have ADHD and 300$ burning a hole in your pocket...

Re: 300 $ to blow on a china girl.....

well i ordered a dax f80 balanced bottom end and a f80 top end -130$

still got 170$ for the carb and intake any suggestions ???

keep in mind this is going to be ported and piston ramped and piston skirt cut with a high comp head (around 12:1) jug will be decked also for tight squish band, and will have a free flowing exhaust with x chamber tunned length .

Re: 300 $ to blow on a china girl.....

i have acsess to a cnc bridgeport milling maching and a lathe so the stock jug is going to be decked and the intake surface will be milled down like the arrow big block jug just not as far and also i will be milling a boost port or mabey 2 skinny boost ports side by side going up the intake . i just need to research where to end the top of the boost port, what the average size the third transfer should be and sutch, and i will be ready for adding the 3rd transfer or 2 smaller transfers side by side. i am not the average guy who barely knows what he's doing though lol i am 32 and have been restoring vintage honda ATC's (the 3 wheeler) since i was 16 ! i know a good amount about engine dynamic comp and valve train componants and yes 2 stroke port timing so i know i can port a jug to do what i want.

the question is ... is it worth the extra money to go with the reed valve set up from arrow ? or just stay with a piston port motor ?

my current grubee gt5 has all the mods possable except for reeds and is a 40 mph bike ! so i do not think they are necacary for speed, but probably do help atomize and meter fuel witch means better milage more low end power and quicker responce.

i could run the volumizer intake from fred with my current CNS v3 carb and it probably would be sufficiant enough to get up to 40 and haul me around town without a problem but i am looking for a 1 shot deal here, i want to build it so there is nothing left to do to it, one stop done . so what i do to it now will be final and i dont want to be wondering if well mabey i should have got this instead or done that to it before.... nope i want the best most reliable set up off the bat and have it make the most power it can.... is that too much to ask ? lol

now i keep lookng at the walbro stage 3 carb from jnm motors, its boared to 15.75 mm so its larger than the delorto and i know from experiance that the walbro carb is a quality piece of hardware and they have an increadably quick throttle responce and are easy to tune as there are no jets, i just can not seem to find any feed back on people using this set up ! i would srsly like to here from people who have it or even from people running the smaller walbro carb the 14mm one ! or any walbro carb for that matter .

the next set up i was eyeing was freds pwer plenum intake and a mikuni carb or dellorto carb, i like the volumizer prinsipal and it seems that fred has put a lot of effort into making the chamber volume just the right size to hold a decent charge for our china girls. this intake i would imagine gives a good boost when comeing off the throttle and rolling on again

then there is always the shorty billit type intake and the cns or dellorto carb

and lastly i could just get the arrow reed valve kit and a dellorto carb or mikuni carb

the 2 i am realy torn between is the arrow reeds and carb or the jnm motors walbro carb and adapter. i just dont know and am not shure yet lol