My 4g Huasheng runs reallllly sloooow.

GoldenMotor.com
Jan 6, 2012
8
0
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Mahomet Il
Well folks, after several months of working on my first build I was finally done. I was ready to cruise down the streets at around 30 mph. But when I rode my bike and give it all the gas, it moved at a snail's pace (No more than 5 miles per hour. My friend suggsted that it could be the gear ratio. I've also heard that I still need to break it in more. I don't think the weight of the bike is a problem and I certainly don't wiegh 500 pounds. So what is going wrong here?

I have a Huasheng V-frame engine with a 4G belt drive transmission. The drive has an 80/10 tooth set up (that is the large wheel has 80 teeth). And my rear sprocket is a 44 tooth (I basically wanted speed). Any help is greatly appreciated.
 

andrewflores17

New Member
Jul 12, 2010
479
2
0
colorado springs, CO
is the bike reving up like it should ?

did you leave the choke on

could the killswitch be just slightly touching something causeing a lack of juice

ur gear ratio sounds good are u realy only doing 5mph or is it a lil more
 

Dan

Staff
May 25, 2008
12,765
115
48
58
Moosylvania
I was thinking the choke as well but even full choke would give you more then 5 MPH. Your ratio should give you around 35 MPH if my questionable math is correct.

Does the engine sound like it is running smoothly?

How is fuel supply?
 
Hi Bronan the Barbarian,

If your primary drive sprocket has 21 teeth and the freewheel has 80 teeth the primary ratio should be 3.8095 X 1. If the output sprocket has 10 teeth and the sprocket on the wheel has 44 teeth, then the secondary ratio is 4.4 X 1. 3.8095 X 4.4 = 16.76 X 1.

If so:
6500 RPM = 30 MPH [29.966] with 26" wheels

Because of the clutch design and size, the ratio could stress the clutch during "take-off". Might try slower starting speeds, as the clutch may be slipping from the 16.76 X 1 ratio, and ease off the throttle to see if it "catches up". We use a similar ratio, however the clutch is much larger and operates differently.

It is hard to determine the exact problem with your build, however I don't think it is because of the top speed ratios.

If the motor doesn't rev-up, then take a close look at the carburetor, as new gas tanks may transfer trash to the carburetor. Often a new tank will have "paint chips" and dirt inside, and don't trust a fuel filter to trap it all. The jets are so small in these motors, it doesn't take much to stop them up.

Let us know if the motor is reving-up, and not getting power to the rear wheel, or it isn't responding to the throttle correctly [higher RPMs].

Have fun,
 
Last edited:
Jan 6, 2012
8
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Mahomet Il
Thanks for the various info everybody. I'm taking all of your advice into consideration and will be resuming work on my bike over spring break. Hopefully it will finally be up and running.
 

The_Aleman

Active Member
Jul 31, 2008
2,653
4
38
el People's Republik de Kalifornistan
The drive will be 20 ---> 80. Not 10, not 21. Assuming your 4G output sprocket is 11T (it could be 10 or 12 instead), that's 16:1. That's a bit of a tall ratio (near the same as my shifter 4G in top gear).

Mine is real sluggish off the line in top gear pedaling. You'd probably have better luck with a 48T. That would give you a 17.45:1 ratio, which would put you near the engine's HP peak at 30MPH. Let's look at clutch lockup speeds (~3000RPM):

10T output, 44T sprocket = 13.3 MPH (31MPH @ 7000)
11T output, 44T sprocket = 14.6 (34)
12T output, 44T sprocket = 16.0 (37)

10T, 48T = 12.2 MPH (28.4 MPH @ 7000)
11T, 48T = 13.4 (31.3)
12T, 48T = 14.6 (34.1)

I suspect you may have the 12T output sprocket. It's a newer, better freewheel output than the 11T, but combined with a 4:1 4G and 44T rear sprocket, it makes for a pretty tall gear ratio.

You didn't answer andrewflores17's question tho: is the engine revving up when you give it gas? If it isn't, you're down on power. If it is, your clutch bell may have seperated.
 

F_Rod81

Dealer
Jan 1, 2011
1,031
2
0
Denver, CO
Also take into consideration that you may have to adjust your valves. Not all 4 strokes are set perfectly from the factory, which could lead to poor performance. Don't neglect what the other members have suggested, but it could be as simple as a 10 minute valve job :). Both the intake and exhaust valve should be set with a feeler gauge at .004 -.005 before warming up the engine. Keep us posted !
 

The_Aleman

Active Member
Jul 31, 2008
2,653
4
38
el People's Republik de Kalifornistan
The valves being out of adjustment isn't going to cause that. My HS once had it's valves at .016/.024 intake/exhaust and I had no problems whatsoever accelerating to 25MPH. Over that it was very sluggish until the valves were adjusted tho.
 
Jan 6, 2012
8
0
0
Mahomet Il
I've made a few adjustment to my build but I'm running into the same old problem.

I think I've sorted out my issues with the choke. I warm up the engine by turning the choke towards the starter chord side, then turn the switch to the drive side to turn it off. Though I would like it if someone gave me a definitive rundown on choke operation.

There is no motor slipping as far as I know. But when I do ride it the engine seems to over rev and the rear wheel doesn't get much if any power.

The Paint and debris coming from the tank shouldn't be a problem, I've got an inline fuel filter. Fuel supply is a little weak with that filter in place but there is always a few inches of fuel in the line.

I think it might just be weight. I'm 6'4 and weigh 210 Ibs and my bike is pretty heavy as well. I might need some bigger sprockets to get torque I need.
 

The_Aleman

Active Member
Jul 31, 2008
2,653
4
38
el People's Republik de Kalifornistan
Attached picture may help with the choke. I drew it like that because I sawed off my choke lever for clearance.
I use full choke to start my engine and as soon as it starts I put the choke halfway. After the engine fully warms up, turn off the choke.
If you find your engine, after being fully warmed up, runs better with a little choke, you're running too lean. I currently have this problem myself.

Your power transfer problem leads me to believe you have an issue with your clutch or clutch drum. I'm almost 6'4" myself and about 25lbs heavier than you, my engine doesn't rev without transferring full power. My clutch almost doesn't slip at all, in fact. Of course these clutches aren't all exactly the same, there's some variance in them spring-wise. You also have not said whether you have a 10, 11, or 12T output sprocket. It makes a big difference. Your ratio seems to be rather tall, but we can't pinpoint it without more info.

Also, do you have a tapered shaft 4G (domed clutch drum) or a straight shaft 4G (flat-side drum)? If you have a tapered shaft version, your clutch may be spinning on it's shaft. if you have a straight-shaft version, you could be missing the key for the clutch.
 

Attachments

Jan 6, 2012
8
0
0
Mahomet Il
Thanks for the choke info. I also cut off the top of my choke lever for clearance.

The output sprocket is 10 tooth and I have a straight shaft 4G with the flat side clutch bell. By key I assume your talking about the Woodruff key that keeps the clutch in place. That isn't missing and it is in the right spot.

I'm still thinking that I just messed up on my ratio by making it too tall.
 

The_Aleman

Active Member
Jul 31, 2008
2,653
4
38
el People's Republik de Kalifornistan
With a 10T output, your ratio is actually quite decent. 17.6:1. You shouldn't be having trouble exceeding 5MPH lol

Did you maybe use too much oil on the bushing and shaft? More than a couple drops every few days can saturate your clutch.
 

Otero

Member
Feb 1, 2010
782
17
18
wa
I had a similar problem; my mixture was set too rich at 2 1/2 turns open. This
will also cause the gas to flush the oil off the rings and seriously damage them.
I was lucky someone clued me in before that happened. If your oil smells strongly
of gas this could be the problem.
 

d_gizzle

Active Member
May 29, 2012
1,102
0
36
43
ARDMORE,OK
Hey there bronan you might look at the one way bearing in the 80 tooth pulley wheel. If it spins freely to the front of your bike that's the REAL problem. I have this problem and for a quick fix imobilize your rear wheel and spin the pulley backwards. It should pop back in to place. If you want a replacement, gasbike.net has them for $10. Make sure not to throttle until the bike is going at least 8-10 mph. Anyone think that's wrong?
:-||
 
Jan 6, 2012
8
0
0
Mahomet Il
Thanks for all of the input everybody! By bike is finally up an running.

Concerning what you said d_gizzle, that actually was one of the problems. I took it apart, removed all of the innards (except the ball bearings) and had a guy weld it into one solid piece. It did shrink a little after it was welded solid but after some metal filing I got it to fit on the drive properly.