Cutting out at half throttle!

[Mr. Minecraft]

I need to pick your brains... Please

I recently cleaned my motorbike down to each part of the carb. Complete rebuild. I reset the valves to .004 intake and .006 exhaust, cleaned out the carby and all the jets, and fixed a few little thinks that needed fixing. The problem is now I have a nice lookin bike, but it won't run for ****. It is very hard to start, and the tuning screw on the side of the carb has no effect on how it runs. Once I get it to start, I can rev it up to 1/2 speed, then if I gun it, the engine chokes out and dies. If I slowly bring it up, I can get it to full speed, but it is not smooth. After this happens and I let off the gas, the engine dies and is VERY hard to start back up.

What do y'all think?

EDIT: This is on a Huasheng 49cc with no mods.

 

[maniac57]

Sounds like something clogging a carb passage. Check it again.

 

[Mr. Minecraft]

Alright ill tear it all apart again and clean it out. Can I just blast the **** out of it with my air compressor, or do I NEED to use carb cleaner?

 

[maniac57]

I use both but air is fine too. Be SURE all the jets are clear. Blow it from every possible angle and passage. I've cleaned them 4 or 5 times and still found trash.

 

[ocho ninja]

Make sure to clean the slow jet and the main jet.
The slow jet is under the idle screw, you need to pop it out and cleaning.
You can also clean the main jet using a thin wire, like a single strand of a break cable works.
Hope this helps

 

[Mr. Minecraft]

I am sure the low jet is clear because it fits i nthe nozzel of my compressor and i blasted it with 80psi . The High speed jet is also clear because did what you said with the thin wire. Still runs the same =/

 

[scotto-]

I need to pick your brains... Please

What do y'all think?

EDIT: This is on a Huasheng 49cc with no mods.

I'all think you should have left it alone as it was probably running fine in the first place. It's prolly a good thing that I'm not your dad cuz in the first place I would be working on my own bike (when and if it did need working on) and would be sure you were listening to me when I was trying to teach you something. I know you're a smart kid but you don't always need to work on things if they're not broken. Computers, bikes, relationships, families don't always need fixing or need to go faster than the speed of light, relax and enjoy them until they really do. Life is short.......enjoy life and your youth ( I must remember to instill this upon my own 4 sons).

Sounds like ya plugged the carb up, it's not hard to do on the 49cc Huashengs.

 

[Mr. Minecraft]

I'all think you should have left it alone as it was probably running fine in the first place. It's prolly a good thing that I'm not your dad cuz in the first place I would be working on my own bike (when and if it did need working on) and would be sure you were listening to me when I was trying to teach you something. I know you're a smart kid but you don't always need to work on things if they're not broken. Computers, bikes, relationships, families don't always need fixing or need to go faster than the speed of light, relax and enjoy them until they really do. Life is short.......enjoy life and your youth ( I must remember to instill this upon my own 4 sons).

Sounds like ya plugged the carb up, it's not hard to do on the 49cc Huashengs.

When I got into the scene of motorized bikes, one of the things that made me join is being able to tinker with the bike whenever I want to learn and improve... Or just for fun What you are saying is true for vehicles that need to be relied on or are important. Part of owning a motorbike is tinkering with the bike.

Also my bike was running kinda rough, and it was covered in dirt so I just did a full overhaul.

 

[scotto-]

When I got into the scene of motorized bikes, one of the things that made me join is being able to tinker with the bike whenever I want to learn and improve... Or just for fun What you are saying is true for vehicles that need to be relied on or are important. Part of owning a motorbike is tinkering with the bike.

Also my bike was running kinda rough, and it was covered in dirt so I just did a full overhaul.

You're right, you will never learn much about these bikes without gettin yer hands dirty. It's good to learn and figure out how to fix things at a young age.....I'm pretty sure I did the same thing as a kid

 

[Mr. Minecraft]

I am very good with engines and such, I just have not taken the time needed to fully understand the carby on these bikes. This is probably because they never break, thus I dont need to work on them.

So to get back on track, I am going to fully re-clean the carb tomorrow and see what happens.

PS: I'm 17

 

[Norman]

You might be beating on the carb instead of looking at other possibilities.
You said you adjusted the valves........ Not to be a smart a#$ but redo your valve lash double check it. Loosen up the adjusters and redo them not just run a feller gauge under them.
Could be you have one too tight or too loose.
I guess your engine was running fine before the tune up? Did you change the spark plug too?
Check your ignition wiring close could be one of the connections is loose or corroded. I think you said something about cleaning it, did you wash it? If so then look over the wiring really close!

 

[Mr. Minecraft]

As far as the valves go, I did fully re-adjust them. They were at .004 intake and .006 exhaust, and I changed them to .003 intake .004 exhaust. I read on here that those settings work well on some of these engines. After I set the valves, the bike was running like complete ****, much worse than now. I quickly switched back to .004 intake and .006 exhaust, and a slight improvement was noticed, but it is nowhere near what it should be.

I when I clean my bike, I get some WD40 and a rag and wipe the entire thing down. Every spoke, screw, and nut is shining when I was through with it. I don't actually spray the bike down like I do to my mountain bike because I believed that it is bad for the engine. Can I do that from now on? (It seems much easier )

Before the tune up it was running alright, but ut had an unstable idle and bogging at WOT, and the tuning screw would not correct these issues, so I suspected a dirty carb. My spark plug is the stock one that came with the kit and it has been working fine since I bought the engine. I live in San Diego and am used to the nice warm weather. Because of this, I am kinda a ***** when it is cold out (below 65f ) so i never ride when its under the 'cold' limit xD. I assume the temps I ride in will affect what plug to buy. What do you suggest?

 

[BigBlue]

Start your bike up at night and look for any arcing or sparks. It's a possibility that you have a cracked spark plug or a broken spark plug wire. Another possibility is to check the gap of your magneto coil and make sure it is securely tightened.

Good Luck,

Chris
AKA: BigBlue

 

[Mr. Minecraft]

Oh I also forgot to mention that I regapped the coil. I did what I do on my gopeds and used a business card to gap it. Is this wrong on these engines?

 

[GearNut]

Cleaning out the slow speed jet with 80PSI isn't going to do diddly if the piece o' crap stuck in it is bigger than the hole it is wedged into. All you are doing is packing it in tighter with 80 PSI of force.
I agree with the brake wire suggestion but I cringe at the size of the individual strands of wire that they are made out of and the fact that it is steel wire.
I recommend stripping back a section of copper speaker wire and using a single strand out of it. Depending on the gauge and construction of speaker (or extension cord, lamp, vacuum cleaner - you get the idea) wire you can get strands of all sorts of sizes to better fit the metering hole.
If you wish to "file" the hole clean you can kink up the wire with alot of bends and run it back and through the hole to really clean it. This will not hurt brass jets as the copper is softer than brass, but...BUT... remember that the slow speed jet on a stock Hua Sheng carburetor is made of plastic. Plastic is softer than copper so be careful that you do not enlarge the teeny metering hole.
Also carefully inspect the o-rings on the jet. If they are not sealing completely then the jet is not "jetting" (metering the fuel properly) and the carb will be all out of whack.

 

[GearNut]

A business card should be fine. I use a strip of 2 liter bottle. It sets the coil closer to the flywheel that specified, but I have never had any issues other than a stronger, hotter spark.

 

[Mr. Minecraft]

Ok so something I forgot to mention is that as far as something plugging up the low speed jet, I can see straight through the hole in the bottom. If i shine a light in the top I can clearly see it shining through the bottom which means there is no blockage there.

I thought about the O-rings being bad. How can you tell when they are not good anymore?

 

[GearNut]

If they are smooshed (pinch smeared?) out past the ring groove, the surface of them is scratched, the cross section of them is not round anymore and rather flush to the ring groove then suspect them of leaking. They need to be compressible by the action of sliding the jet back into the carb body by at least 20% or more.

 

[BigBlue]

Here's a video on cleaning the slow jet from Dwayne at ThatsDax. The jet is very tiny and I don't know if blasting air will clean it out. He uses some very small drill bits to clean out the jet. As Dwayne states in his video, don't make the just bigger. Like GearNut stated, you may just be lodging dirt farther into the jet: https://www.youtube.com/watch?v=QtBl63kWO7Q&list=UUG6sGQn2cjX0-Y6ymffT7JA&index=59

Not to question your skills, but you did adjust the valves with the engine cold and the piston at TDC? You also double checked the clearance after you tightened the lock nut. By the way, Dwayne recommends .05mm on both the intake and exhaust for the Titan.
http://thatsdax.com/TITAN_VALVE_CLEARANCE_ADJUSTMENT_PAGE.html

Good Luck,

Chris
AKA: BigBlue

 

[GearNut]

Some other thoughts I had on the carb.
We all here seem to be zeroing in on the slow jet due to the uneven idle you referenced to, yet you also have a high speed problem with dying upon dropping the throttle.
Enough with messing with the jet, how clean are the ports and passages in the carb body?
Does the throttle plate shaft have any slop in fitment to the carb body? If so then that is an air leak. How is the seal between the carb and the head? There are 2 gaskets and a plastic heat block there that can leak.

Air leak = weird idle and poor high speed performance.
Could also be an issue with the fuel...got water?
Float height could do it, set too low. Although the float did not look adjustable in mine when I dropped the bowl though, it is all plastic and I don't recall seeing a metal adjusting tang.
A restriction in the fuel delivery from the tank to the float bowl could cause high speed issues but not do much to the idle so I hesitate to go there.
The worst I can see as a culprit is a burned or bent valve. Can't rule it out, but I doubt it is the problem. Have you tried a compression test or leak down test? Don't go tearing into the head until the basic tests have been done first.