HS 142F Low-End Bogging

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JeremyD

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Sep 1, 2012
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I find myself once again turning to the expert advice of the motorbicycling forum...
Anyway, my HuaSheng 49cc came in the mail on Saturday, and i finally got it mounted on my bike, along with the gas tank and did a test run (no drive chain). I have to admit I was slightly surprised that it started at all, but even more surprised that it started on the second pull. It idled like a dream, but when I revved it, it bogged to the point of stalling. I started it again and gave just a little throttle, but this time it bogged and just barely kept running but when I heard it bog, I immediately released the throttle, and it revs way up almost like it was catching up for all the gas it didn't burn while it was dieing. I've repeated this experiment after the engine has warmed for about 5 minutes as well.
I should also note that "the 2012 model engines will not have a fuel/air mix adjustment screw in the carburetor"! So I guess if that really needs to be adjusted, I would have to get a Honda carb, right? The point is, I don't even know if the carb is the problem!
I don't have a lot of experience with small engines, and I would appreciate any guidance!
 
MotorBicycleRacing

MotorBicycleRacing

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JeremyD said:
I find myself once again turning to the expert advice of the motorbicycling forum...
Anyway, my HuaSheng 49cc came in the mail on Saturday,
I should also note that "the 2012 model engines will not have a fuel/air mix adjustment screw in the carburetor"! So I guess if that really needs to be adjusted, I would have to get a Honda carb, right? !
Click to expand...
Are you sure that there is no fuel/air mix adjustment screw in the carburetor?

it's the screw on the left side right next to the engine.
do you have a pic of your carb?

You do not say where you bought your kit or what gearbox it comes with?

Your problems sound carb related.
 
The_Aleman

The_Aleman

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Jul 31, 2008
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If the new engines do not have an air screw, that does not bode well for their use on bikes. Well, at least until the carburetor is swapped for one that does! Double-check to see if it's there: it will be down and to the left of the idle adjustment screw. The idle screw is a large black Philips-head screw, the air adjustment screw is a small brass one with a slot-head.

One of the first things that should be done after mounting the engine, adding oil, and hooking up the fuel is to adjust the air screw. 2-2.5 turns out is the norm. Some engines like more, some like less, but a basic adjustment should be done before running the engine. After it's running and warmed up, then fine-tuning is in order.

It's also not really good to run a new engine without a proper load. The rings won't seat as quickly and with extended running without loading, may prematurely degrade the cross-hatching on the cylinder wall. Get your drivetrain finalized so you can run the engine properly!

If your carburetor does indeed lack an air screw, I recommend finding a Huasheng carb that does. A Honda carb lacks the throttle linkage (there are kits to remedy that tho) and it's been said that the Honda carb has a smaller main jet, too. A Honda carb + throttle linkage will be quite expensive compared to just a Huasheng carb.
 
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JeremyD

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I bet you $20 that you can't find a mixture screw on this carb.
It's just a brass circle where the screw should be.
Also it was from gasbike.net with a 4G belt.
 
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MotorBicycleRacing

MotorBicycleRacing

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JeremyD said:
I bet you $20 that you can't find a mixture screw on this carb.
It's just a brass circle where the screw should be.

Also it was from gasbike.net with a 4G belt.

Click to expand...
OK, I owe you $20 :)
Would like to see them but Your pics aren't working because they aren't jpegs

What model of 4G does gasbike have in the kit?
5/8" shaft or clutch built into the motor?

Sometimes those anti tamper covers can be removed.
 
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JeremyD

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MotorBicycleRacing said:
When the carb is off what does the needle look like in the carb throat?
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You'll have to bear with me, I don't have any experience with small engines other than my lawnmower (which is made in the USA and has worked flawlessly for 15 years, just saying).

Is this what you're referring to?
 
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JonnyR

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if you have a small enough drill bit and screw driver you an drill out the plug (carefully) and the screw should be behind it. i have done this to the stupid EPA CNS carb
 
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JeremyD

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Sep 1, 2012
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Colorado
JonnyR said:
if you have a small enough drill bit and screw driver you an drill out the plug (carefully) and the screw should be behind it. i have done this to the stupid EPA CNS carb
Click to expand...
A screw behind something that was never supposed to be removed? Bunch of real geniuses over there.
How thick was the plug? (So I don't screw up the screw)

And if I can find this elusive adjustment, do I need to go leaner?
 
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JeremyD

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Sep 1, 2012
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JonnyR said:
its thin as h3ll its 1/16 inch thick or so
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It was just over 1/8 inch on mine. I took it out two turns and she purrs like a kitten now.
I still can't believe someone in their right mind would sell a carburetor without access to the fuel/air adjustment. I would have had no idea what to do without you guys. Thanks a bunch.

.rd.
 
MotorBicycleRacing

MotorBicycleRacing

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JeremyD said:
It was just over 1/8 inch on mine. I took it out two turns and she purrs like a kitten now.
I still can't believe someone in their right mind would sell a carburetor without access to the fuel/air adjustment. I would have had no idea what to do without you guys. Thanks a bunch..
Click to expand...
It's 2012 EPA BS the same as they already messed up the 2 stroke carbs.

Thank you for the very good pics and the heads up on the new kits.

How did you get the plug out?
Did you check how many turns the EPA set the screw out?
 
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JeremyD

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Sep 1, 2012
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Colorado
BigBlue said:
It is easy to remove the plugs with a sharp scratch awl.
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It actually wasn't on mine. I found it much easier to get a drill bit slightly smaller than the plug and just make shavings til there's nothing left. (Well there was actually a thin lopsided cylinder left.)
MotorBicycleRacing said:
Did you check how many turns the EPA set the screw out?
Click to expand...
I didn't have the presence of mind to check it right away, but I said I took it out about 2- 2.5 turns, and I just checked now, it only goes in about 4 turns. (4 - 2.5 ~= 1.5?)
 
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