Removing welch plug HuaSheng 49cc 4 stroke

Mike_Honcho

Mike_Honcho

New Member
I though i would just post these pics to help, although i still don't know why I would make the bike run a little richer... The motor is running fine before removal, higher rev?
 

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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
 
Tom from Rubicon said:
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
Click to expand...

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! ;)
 
Tom from Rubicon said:
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
Click to expand...
He removed the correct plug.
The plug covered the air mixture screw.
Do not remove the plug in the counterbore just to the right.

image2-jpeg.100030
 
Tom from Rubicon said:
Norm, I have a first build HuffyDavidson with carb trouble. What 2stroke carb do you recommend?
Tom from Rubicon
Click to expand...
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)
 
Tom from Rubicon said:
Thanks for the info Norm. what diameter drill. I'm a Tool and Die Maker with many drill sets.
Tom from Rubicon
Click to expand...
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
 
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. ;)
 
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
 
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