New China girl carb problem..help!

nomad69 · Feb 27, 2017

I took off the float box, and that brass fitting that holds the throttle pin in place, wasn't even screwed into the main carb body. Someone at the factory forgot to screw it in...sheesh. Got it put back together and still having the same problem.

Is there an upgraded carb for this motor? an if so, where can I get one and which model would you recommend?

The first china girl I had a different style of carb, never had one problem with it!

IMHO this carb design...SUCKS

nomad69 · Feb 27, 2017

Took the float apart again and found that brass sleeve vibrated loose again. Took a wrench to it this time.

Got it started and got to idle fine. Now when engine is engaged and trying to get me up to full speed, I have to peddle assist it. I even think I heard it back fire.

Basically it's having a real hard time getting up to speed. I did move the "c" clip up one notch to make it leaner, because the plug was wet, maybe I should set it back at factory...any thoughts?

I'm still running the break in fuel mix...? could be the problem? 20:1

crassius · Feb 27, 2017

I'd just keep it running for a while, as it may be full of fuel and could straighten out as it dries.

nomad69 · Feb 28, 2017

Tighten the head, muffler, carb nut's. Cleaned the spark plug and adjusted the C clip back to factory setting and put some fresh gas in.

She idles nice now and runs much better through low to high with load on it, but it still seems she's kind of sluggish, maybe she needs a couple more tank fills. It seems she needs more air?

Is there a screen inside the muffler that gets clogged?

TIA..

Potato_In_Exhaust · Feb 28, 2017

nomad69 said:
Tighten the head, muffler, carb nut's. Cleaned the spark plug and adjusted the C clip back to factory setting and put some fresh gas in.

She idles nice now and runs much better through low to high with load on it, but it still seems she's kind of sluggish, maybe she needs a couple more tank fills. It seems she needs more air?

Is there a screen inside the muffler that gets clogged?

TIA..

Try running your motor without the filter on it, only the filter housing and see how she runs.... I bought mine that came without the filter and it hasn't cause me any trouble yet, the previous owner tuned the motor to run without the filter because when I bought a filter to put it on, it wouldn't even run so I didn't want to go through the headache of trying to make it run right and just left it. Plus it will increase a bit of horsepower, YO!

But just don't blame me should a pebble sneak up through there and destroy your motor.

Tyler6357 · Mar 1, 2017

Sorry I haven't replied lately but I don't know what to say, seems like a air/gas mixture problem. Make certain there are no leaks at the carb/intake connection, intake/intake manifold connection, and leaks around the head. If you don't find any, you could try running it without the air filter just to see if you are getting enough air through it. if it runs ok without the air filter it must be clogged or something, just replace the air filter or if you think something is wrong with the carb just buy a new carb. The other thing you could try is getting a smaller jet. I'm pretty sure that the stock jet that comes with the NT carb is #75.

Air Filter Stock NT--> http://www.ebay.com/itm/1pc-Air-fil...ash=item4ae02c73ba:g:ZsIAAOSw7NNUGpNC&vxp=mtr

Stock NT Carb--> http://www.ebay.com/itm/Nt-Carburet...ash=item43ea36a862:g:x60AAOSwQYZWzNno&vxp=mtr

Jets--> http://www.ebay.com/itm/231458900645?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

Jets--> http://www.ebay.com/itm/271748133936?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

nomad69 · Mar 1, 2017

NP tyler ... thanks for the reply

I'll take off filter and see if it runs better. Gonna pick up smaller jets too. Where is the jet located in the carb.

Can I run a hotter plug and what is the gap

Tyler6357 · Mar 2, 2017

nomad69 said:
NP tyler ... thanks for the reply

I'll take off filter and see if it runs better. Gonna pick up smaller jets too. Where is the jet located in the carb.

Can I run a hotter plug and what is the gap

Here is a video showing how to replace the jet--> https://www.youtube.com/watch?v=J6wcs6D2baM

Here is a video that might help you tune your carb--> https://www.youtube.com/watch?v=l0s-aCPJf4c

The spark plug gap should be about .025". I use a NGK B8HS spank plug but you could use a B7HS or B6HS if you want to try a hotter plug. Good Luck!

nomad69 · Mar 3, 2017

This carb ain't complicated, it's a whole lot of fine tuning. This is one way of getting to know your china girl.. My first girl ran like a charm out the box, but had a different carb... dunno.

Gonna take off air filter and adjust plug, and new jet.

She still is chugging and can't get up to full speed without peddle help.. something ain't right. I've ran 2 tank full's so far, and this problem should have gone away no matter what fuel mix I run.

New chain is working great and smooth, engine idles ok, but seems to need 5-10 min warm up and still cant transition from idle to full throttle smoothly or at all.... It bogs

Tyler6357 · Mar 4, 2017

Well, I upgraded mine to the RT type of carb (Dellorto Clone) and it seems easier to tune. But I have also upgraded my pipe with an expansion chamber, put a high compression head on, and put 15mm intake on it too, all of these things can change tuning. You should try jetting down, try a #70. Is it four-stroking?

nomad69 · Mar 4, 2017

What is "4 stroking?"

I start the bike, let it warm up, hop on and start peddling, I give it throttle and it bogs. I literally have to pedal assist the engine to maintain what ever speed I'm at. Won't climb even slight incline without peddle assist.

Is it starving for gas or is to rich? I have the c clip in the middle setting.. gonna take it out now with out the carb filter and see if that's part of the problem.

Potato_In_Exhaust · Mar 4, 2017

I think it's running too rich, you should try playing with the jets if you have any.

nomad69 · Mar 4, 2017

Took off filter got it idling and still the same problem. When I go from idling to full throttle it hesitates and sputters as it goes to full throttle...not very smooth nor quick.

Agreen · Mar 4, 2017

Sputtering is 4 stroking, and means it's too rich. Bogging without spits and sputtering is too lean.

I haven't looked back through the rest of this topic, but verify that your spark plug is clean, gapped at about 0.025", and all bolts (including head bolts) are tight. If it's all good, go down a size or 2 in the jet. You can either buy a jet kit or solder it and drill it out.

nomad69 · Mar 4, 2017

Well just got done doing another carb adjustment. All the videos I've watched say that these engines like the "e" clip 2nd from the top. So wanted to see if I moved the "e" clip 2nd to bottom. Here are the results. I can get up to speed much better and faster and stay there, but now I'm having constant back firing.

Any thoughts?

I've got jets on order 66 through 70....

nomad69 · Mar 4, 2017

Took the bike for a long ride and by moving the e clip down one notch from center, the bike is running pretty good now. She gets to 20 mph now and can sustain it...for the most part. Gonna fool around with the jets when they come in.

20 mph top end seems a little low though. My last china girl could reach 25-30 mph. dance1

MotorBicycleRacing · Mar 4, 2017

nomad69 said:
Took the bike for a long ride and by moving the e clip down one notch from center, the bike is running pretty good now. She gets to 20 mph now and can sustain it...for the most part. Gonna fool around with the jets when they come in.

20 mph top end seems a little low though. My last china girl could reach 25-30 mph.

20 mph is not right or good.
How does it run with the clip on the top notch?

just get a 65- 66 jet. Stock is usually a 70

When you put the 66 jet put the clip back in the middle needle notch.

nomad69 · Mar 4, 2017

Runs like crap 2nd notch from top. I'll put the new jet in next week and I'll report my findings.

Tyler6357 · Mar 4, 2017

Ideally, when the piston reaches it's top (closest to the head) compression is at it's maximum and the spark should explode the fuel. Four stroking is a condition where sometimes the ignition doesn't occur, this can happen once every several 100 strokes. You will hear it happening, a "pop, pop, pop" every few moments. It is caused by a rich condition and is solved by jetting to a smaller jet which will restrict the amount of fuel sucked into the intake. Often times as the engine warms up and gets hot it will run slightly leaner and the four stroking will stop. It's important to remember that it's always better to be too rich than to be too lean. A lean condition will cause increased heat and increased heat will cause engine failure. A rich condition causes four-stroking, bogging, and loss of power.

nomad69 · Mar 7, 2017

I put the #67 jet in and moved the clip to the middle. Lots of blue smoke coming out of the muffler. So I moved the clip back down one notch to 2nd from bottom, and it ran a little better, but still isn't running at full speed. Now I can only get to 15 mph. With clip in 2nd from bottom it doesn't blow smoke near as much. Engine still seems like she's sluggish

crassius · Mar 7, 2017

excessive smoke often means petcock was left in "on" position while nit running and this will clear up after 20min or so of running

New China girl carb problem..help!

New Member

New Member

Well-Known Member

New Member

Member

Well-Known Member

New Member

Well-Known Member

New Member

Well-Known Member

New Member

Member

New Member

Member

New Member

New Member

Well-Known Member

New Member

Well-Known Member

New Member

Well-Known Member