Removing welch plug HuaSheng 49cc 4 stroke

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
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That "was" an idle circuit screw. It did have a driver slot to adjust it. The counterbore just to the right is the plug you wanted.
Norm correct me if I am wrong.
Carbs a cheap. Welcome to the club.
Tom from Rubicon
You're correct.... that was a idle screw!

Actually, this would be a great time to swap out that carb for a 2-stroke carb conversion! ;)
 
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MotorBicycleRacing

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That "was" an idle circuit screw. It did have a driver slot to adjust it. The counterbore just to the right is the plug you wanted.
Norm correct me if I am wrong.
Carbs a cheap. Welcome to the club.
Tom from Rubicon
He removed the correct plug.
The plug covered the air mixture screw.
Do not remove the plug in the counterbore just to the right.

 

Venice Motor Bikes

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Mar 20, 2008
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Norm, I have a first build HuffyDavidson with carb trouble. What 2stroke carb do you recommend?
Tom from Rubicon
Tom, this is it... https://www.gasbike.net/collections/4-stroke-parts/products/4-stroke-nt-carburetor

This is a much better manifold... https://www.gasbike.net/collections...s/49cc-nt-carburetor-intake-for-4-stroke-long

If you use this carb?, you'll probably have to install a slightly larger jet. (or just drill it if you can get a 'jewlers' drill bit set)
 
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MotorBicycleRacing

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Thanks for the info Norm. what diameter drill. I'm a Tool and Die Maker with many drill sets.
Tom from Rubicon
Stock NT jet is a 70 so try a #69 drill bit
Use number drills.

#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
 
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Venice Motor Bikes

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I usually drill two sizes bigger, but your engine might want something different.

If you feel you've drilled too big?, you can easily close the jet hole with a pinhead size dot of electrical solder & re-drill it to a smaller size. ;)
 
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Tom from Rubicon

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Hey Norm,
#68 drill is logical, .003 larger won't over feed the engine.
Run it and give the sparkplug a hard look.
Been screwing around mounting Wald fenders on my Sportsman 80. Thanks for the input. Hope Mike is absorbing all this good info.
Tom from Rubicon