Motorized Bicycle Engine Kit Forum  

Sponsors



Go Back   Motorized Bicycle Engine Kit Forum > Motorized Bicycle > Motorized Bicycle General Discussion

Motorized Bicycle General Discussion All topics regarding bicycles with engines.

Reply
 
Thread Tools Display Modes
  #51  
Old 03-10-2017, 06:15 PM
MotorBicycleRacing's Avatar
MotorBicycleRacing MotorBicycleRacing is offline
Motorized Bicycle Elite Member
 
Join Date: Jul 2010
Location: SoCal, Orange County.
Posts: 5,532
Exclamation Re: New China girl carb problem..help!

Quote:
Originally Posted by Agreen View Post
mm!? 70mm is almost 3 inches!
#70 drill bit = jet = 0.028" = 0.7112mm Jet size!!!!

#BitSize Inches Millimeters Jet Size

#80 0.0135 0.3429 34.29
#79 0.0145 0.3683 36.83
1/64" 0.0156 0.3969 39.69

#78 0.016 0.4064 40.64
#77 0.018 0.4572 45.72
0.5mm 0.0197 0.5 50

#76 0.02 0.508 50.8
#75 0.021 0.5334 53.34
#74 0.022 0.5715 57.15

#73 0.024 0.6096 60.96
#72 0.025 0.635 63.5
#71 0.026 0.6604 66.04

#70 0.028 0.7112 71.12
#69 0.0292 0.74168 74.168
0.75mm 0.0295 0.75 75

#68 0.031 0.7874 78.74
1/32" 0.031 0.7938 79.38
#67 0.032 0.8128 81.28

#66 0.033 0.8382 83.82
0.85mm 0.0335 0.85 85
#65 0.035 0.889 88.9

#64 0.036 0.9144 91.44
#63 0.037 0.9398 93.98
0.95mm 0.0374 0.95 95

#62 0.038 0.9652 96.52
#61 0.039 0.9906 99.06
1mm 0.0394 1.0 100
#60 0.04 1.016 101.6
Reply With Quote
  #52  
Old 03-10-2017, 06:23 PM
MotorBicycleRacing's Avatar
MotorBicycleRacing MotorBicycleRacing is offline
Motorized Bicycle Elite Member
 
Join Date: Jul 2010
Location: SoCal, Orange County.
Posts: 5,532
Default Re: New China girl carb problem..help!

Quote:
Originally Posted by crassius View Post
NT jets are in mm - a 70 flows more fuel than a 68
Correct.
A #70 jet is 0.7mm

Last edited by MotorBicycleRacing; 03-10-2017 at 10:22 PM.
Reply With Quote
  #53  
Old 03-10-2017, 06:48 PM
crassius's Avatar
crassius crassius is offline
Motorized Bicycle Elite Member
 
Join Date: Sep 2012
Location: USA
Posts: 3,072
Default Re: New China girl carb problem..help!

jets are in mm at .70mm
__________________
Sometimes I sets and thinks, sometimes I jes sets.
Reply With Quote
  #54  
Old 03-10-2017, 08:55 PM
Agreen's Avatar
Agreen Agreen is offline
Motorized Bicycle Elite Member
 
Join Date: Feb 2013
Location: Southeastern GA
Posts: 784
Default Re: New China girl carb problem..help!



(Sorry, arguing semantics is my form of entertainment)

Anyway, the point is that there are different ways that jets are labeled, so be careful!

A #70 is close in size to a .70mm jet, but that's the only one! A #68 jet goes up in size, but going to a .68mm jet is going down.
__________________
Never stop wrenching
Reply With Quote
  #55  
Old 03-10-2017, 10:10 PM
MotorBicycleRacing's Avatar
MotorBicycleRacing MotorBicycleRacing is offline
Motorized Bicycle Elite Member
 
Join Date: Jul 2010
Location: SoCal, Orange County.
Posts: 5,532
Default Re: New China girl carb problem..help!

Quote:
Originally Posted by Agreen View Post
(Sorry, arguing semantics is my form of entertainment)

Anyway, the point is that there are different ways that jets are labeled, so be careful!

A #70 is close in size to a .70mm jet, but that's the only one! A #68 jet goes up in size, but going to a .68mm jet is going down.
Not semantics, you are just wrong.
Jet are labeled by size in mm and not by the drill bit that makes them.

100 jet is 1.0 mm
70 jet is 0.7 mm
68 jet is 0.68 mm
34 jet is 0.34 mm

The jet sizes are the far right column.

The first column of numbers is DRILL BIT # or size.
You can't drill all jet sizes with what is commonly available.
You can drill a 66 jet then jumps to a 71 jet jumps to a 74.

#70 drill bit = 0.028" = 0.7112mm = Jet size!!!!

#BitSize Inches Millimeters Jet Size

#80 0.0135 0.3429 34.29
#79 0.0145 0.3683 36.83
1/64" 0.0156 0.3969 39.69

#78 0.016 0.4064 40.64
#77 0.018 0.4572 45.72
0.5mm 0.0197 0.5 50

#76 0.02 0.508 50.8
#75 0.021 0.5334 53.34
#74 0.022 0.5715 57.15

#73 0.024 0.6096 60.96
#72 0.025 0.635 63.5
#71 0.026 0.6604 66.04

#70 0.028 0.7112 71.12
#69 0.0292 0.74168 74.168
0.75mm 0.0295 0.75 75

#68 0.031 0.7874 78.74
1/32" 0.031 0.7938 79.38
#67 0.032 0.8128 81.28

#66 0.033 0.8382 83.82
0.85mm 0.0335 0.85 85
#65 0.035 0.889 88.9

#64 0.036 0.9144 91.44
#63 0.037 0.9398 93.98
0.95mm 0.0374 0.95 95

#62 0.038 0.9652 96.52
#61 0.039 0.9906 99.06
1mm 0.0394 1.0 100
#60 0.04 1.016 101.6

Jets for NT carbs are available here.
http://sickbikeparts.com/carb-jets-n...-5mm-main-jet/

Last edited by MotorBicycleRacing; 03-10-2017 at 10:32 PM.
Reply With Quote
  #56  
Old 03-11-2017, 12:01 AM
Agreen's Avatar
Agreen Agreen is offline
Motorized Bicycle Elite Member
 
Join Date: Feb 2013
Location: Southeastern GA
Posts: 784
Default Re: New China girl carb problem..help!

Well I'll just go ahead and... pull this foot out of my mouth here...

Ahh, that's better.

I guess I never made that connection somehow. Maybe because I drill all my own jets and don't fool with buying them. I don't like to wait for shipping
__________________
Never stop wrenching
Reply With Quote
  #57  
Old 03-20-2017, 01:14 AM
nomad69 nomad69 is offline
Motorized Bicycle Member
 
Join Date: Feb 2017
Location: midwest
Posts: 27
Default Re: New China girl carb problem..help!

The higher the # the leaner? 70+ or visa/versa?
Reply With Quote
  #58  
Old 03-20-2017, 12:26 PM
MotorBicycleRacing's Avatar
MotorBicycleRacing MotorBicycleRacing is offline
Motorized Bicycle Elite Member
 
Join Date: Jul 2010
Location: SoCal, Orange County.
Posts: 5,532
Default Re: New China girl carb problem..help!

Quote:
Originally Posted by nomad69 View Post
The higher the # the leaner? 70+ or visa/versa?
100 jet is 1.0 mm
70 jet is 0.7 mm
68 jet is 0.68 mm
34 jet is 0.34 mm

A 34 jet is leaner than a 68 jet because it's a smaller hole.

The jet that comes with most of the stock carbs is a 70
Going down to a leaner ~66 jet will make it leaner.

Also the needle tapers so as you drop it lower by putting
the clip on a higher notch the opening of the tube is reduced
making it smaller and leaner.
Reply With Quote
  #59  
Old 03-21-2017, 12:57 PM
Potato_In_Exhaust Potato_In_Exhaust is offline
Motorized Bicycle Elite Member
 
Join Date: Feb 2017
Location: California
Posts: 129
Default Re: New China girl carb problem..help!

For the love of gawd, someone go to the poor sap's house and help him out with his bike! I feel like the guy is on the verge of a mental break down!
Reply With Quote
  #60  
Old 03-23-2017, 10:52 PM
nomad69 nomad69 is offline
Motorized Bicycle Member
 
Join Date: Feb 2017
Location: midwest
Posts: 27
Default Re: New China girl carb problem..help!

Ahhhhh... I'm not about to break down, 20mph on 2nd tank full... I'm 245 with 50 cc bike, i'll tune it right, it ain't my first china bomb.

I'm looking for a muffler clamp that fits a 3 inch mountain bike frame?
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 02:57 PM.


Sponsors

Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
MotorBicycling.com