Flat out or nothing?

brett7777

brett7777

New Member
Is there any in-between way to ride with a China girl motor> I find that at half acceleration the whole bike shudders so much, it only smooths out at high revs (flat out), also shudders a lot as you accelerate.
 
Yes.

My 48cc grubee does very well at low and mid rpm even though it's running too rich.
Lots of torque for what the motor is. and I weigh 230.

Have a quick look at your sparkplug and see how it reads.

My guess is the carb needs re-jetting.

Good luck
rc
 
It runs fine, that's not the issue. There's no missing or anything like that. I just dont understand why it is that as you accelerate & release the clutch that there is so much vibration of the bike.
 
Make sure the motor is secure and tight to the frame. I have had the motor mounts break before and it feels like the motor has blown up, so check that...
 
Frame looks fine as far as I can see.
What I dont understand, is that when I rev the bike while it's stationary, it revs smoothly, but when I accelerate with the bike in motion, it shudders like crazy until it reaches near to or top speed.
Is there any clutch adjustment for these motors? Could that be something to do with my problem?
 
They all shudder a little bit on take off I would say thats normal . Are you pedaling on take off or trying to motor away from a stop. If you are trying to get it going without any pedaling you might have glazed the clutch pads . There is a clutch adjustment as well under the right motor cover . do a search on here should be easy to find .
 
Yeah once the motor is going I have been using the clutch to pull away from a stop. Are you not meant to do that? Should I be pedalling with the clutch in & then once I have some speed, then let the clutch out?
It feels like the feeling you get when your gearing is wrong for the speed you are going - that is, it shudders on acceleration AND deceleration, but is fine once you get up speed. It also shudders much more if you try & go up any kind of hill.
 
Sounds like clutch chatter to me, you may have glazed the pads on a hard take off... have a look, if its not glazed try adjusting the clutch "IN" tighten the star nut two turns at a time, remember not to loose the tiny clutch locking screw.
FR
 
FarRider said:
Sounds like clutch chatter to me, you may have glazed the pads on a hard take off... have a look, if its not glazed try adjusting the clutch "IN" tighten the star nut two turns at a time, remember not to loose the tiny clutch locking screw.
FR
Click to expand...

Thanks FR. Wouldnt even know where to start. This happened from the very first startup & run - since then Ive done about 20 trips up & down our little side street.
Would the clutch glaze straightaway like that?
Is this star nut under the gearcase cover somewhere? where is this locking screw that you speak of?
 
The cover he's talking about is on the right hand side of the motor. Its the only cover on that side. It has 5 bolts i think. Take it off then u see the big silver plate. See the screw next to the center star screw. Take the small screw out. Thats the locking screw. Then turn the star nut clockwise however many times he said, I think was 2 turns. Then, put the small screw back in, then the cover on , and tighten the bolts, then get on your bike, put the choke so the end of the handle is facing up and then hold the clutch handle in, pedal till your up to a decent speed and then let go of the clutch handle and give it throttle, once the motor kicks to life, pull the choke down. The choke handle is on the right side of the carbuerator. That is if u have the nt carb(one with the round air cleaner cover that has the vents on the bottom(looks like 4 pips coming out of the carb).
 
Thanks. For a brand new motor, where do you get the specs of using '2 turns' for the star nut? Is that just a standard adjustment for all new motors?
 
brett7777 said:
Thanks. For a brand new motor, where do you get the specs of using '2 turns' for the star nut? Is that just a standard adjustment for all new motors?
Click to expand...

What kind of motor do you have, specifically the carb?

These kits are NOT geared to be able to pull you from a dead stop, you need to pedal to get rolling and THEN let out the clutch. My brother has a couple 50cc minibikes, they have a 3 speed trans on them. After riding them I came away looking at my motorized bike like the first gear is the HUMAN gear, second gear is the motor, third gear dont exist! So you pedal to start, ride nice on the motor from about 5-30MPH and on the top end you can only wind it out instead of being able to shift to 3rd.....

Now, back to your problem. If you have a rough ride between 8-15MPH you might need to do some carb adjustment, specially if you have the CNS carb....
 
Someone finally answered my question about whether you can use the motor & clutch (without pedals) to take off from a stop - thanks. I will pedal until I have enough momentum.
I have the NT carb.
How do I adjust it? I only see an idle speed screw (which I had to turn in as it didnt idle initially)
 
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brett7777 said:
Someone finally asked my question about whether you can use the motor & clutch (without pedals) to take off from a stop - thanks. I will pedal until I have enough momentum.
I have the NT carb.
How do I adjust it? I only see an idle speed screw (which I had to turn in as it didnt idle initially)
Click to expand...

You're welcome.
I have the CNS carb and it's a really picky beast. I hear the Speed and NT carbs are easier to deal with, need less tuning etc. CNS has 3 jets, NT and Speed only have 1, NT and Speed carbs are reputed to run better without too much tinkering, the CNS is another (long) story.....
One thing that might need adjusting on either carb, specially if the carb does not sit level, is the float. I found my float was letting too much fuel in the bowl and that made my low end ride very rough (again, CNS carb), this MIGHT be an issue for you. Try this to test, warm up the bike then turn off the valve on the fuel line, if the bike starts running smoother shortly after the valve is turned off (before it runs out of fuel) then you probably would benifit from doing a float adjustment.
 
Thanks NC.
Ive already done that a couple of times (by forgetting to turn the valve on) & it didnt change anything. Also the carb is level.
I wouldnt have thought it would need a different size jet right from get go, would it?
I cant help wondering about the clutch. You know if I dont let the clutch lever all the way out (hold it in a bit & not fully disengage it) then all the shuddering disappears. Of course Ive only only tried that a couple of times because I can tell the motor is not fully engaging & I dont want to wreck the clutch. But it made me wonder.
 
Im not discounting the carb thing tho. I guess if it wasnt doing what it was meant to do then it could cause this problem. You are right, it's in the 8-15mph bracket.
 
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