Troubleshooting a Huasheng 4-stroke Engine

[Member 28661]

UPDATE: So I took the carb apart and it doesn't look good. From the looks of the fuel bowl there's this flaky almost muddy deposit that's forming. This residue was on the jet as well (pictures below). Not even 3 weeks ago I cleaned and disassembled the carburetor. Could this be causing the jet to get clogged and not let in fuel? I'm trying to think where this is coming from, fuel tank or the fuel filter?

Here's the picture of the jet, as you can see it looks like that residue is on the the jet as well. I took a small bread tie, stripped it to the wire, poked it in the jet and freed anything blocking it. I tried to unscrew the jet counterclockwise and it won't budge so I'm not going to try. Don't want to chip another piece off of the brass.

I managed to clean and reassemble the carburetor. Now all that's left to do is put a new piece of fuel line leading to the fuel intake on the carb as it has a leak.
I'm trying to figure out why the deposit is forming and what it could be from. I'm not sure if it's from fuel sitting around as I put fresh fuel in the tank and it's been sitting for less than 3 weeks since the last carb clean.

 

[Member 28661]

BIG UPDATE: Great news! The motor has finally fire up! Idles sound pretty good. Not perfect, its a little chopping here and there. RPM stays low for the most part then occasionally goes up for a split second. Also it runs great without the choke on, if I put on the choke the motor sputters then dies. Also when I increase the throttle the motor dies as well. How would I be able to tune the motor to make it run better, A/F mixture and idle wise? BTW The A/F mixture screw is 3 turns out and the idle screw is 1-1/2 turns in.

 

[hazmat]

Hello MotorBikes.com I'm Matt, a new member to this forum, however I've been working at this motorized bike for close to 3 years now and I've only got it running a hand full of times unfortunately. First a little bit of background about the bike. I first purchased the Huasheng 4-Stroke engine kit at GasBike.net along with the 4 stroke shift kit at Sickbikeparts.com back in 2015. Also purchased a mountain bike and upgraded Shimano hydraulic brakes. After having assembled the bike in the summer of 2015, I did manage to get it running a hand full of times with the top speed clocked at 45mph. After about 2 rides on it I noticed the engine mount was sliding downward on the frame thus putting slack in the chain, fixed the issue with the mount.

After having the motorized bike sit for quite a while roughly 2 years, I tried to start it up again recently and it wouldn't fire up. So I took apart the carburetor cleaning every part meticulously (tons of old fuel lacquer inside the carb), cleaned the fuel tank, put in new fuel lines, new fuel filter, new on/off fuel valve and new fuel. I also replaced the cheap chinese spark plug included in the kit with an new NGK plug.View attachment 81202
This boils down to the current issue that I'm having with the Huasheng 4-Stroke 49cc engine not wanting to start no matter what I try. After replacing most of the fuel components, new spark plug and carb cleaning it's still a no go. I've even tried pulling the throttle a little bit to put some fuel in the cylinder when pull starting it, but it still doesn't start up. I've also looked at the engines compression and it looks good. View attachment 81204
After doing some research online I've come to the point that I think the reason for the bike not starting is that the air-fuel mixture is off. Doing some research I've found that the mixture can be adjusted with a screw located on the back of the carb(pictured above). It appears that the carb that came with my motor has a brass plug in the place of the adjustment screw.

Would this be a problem with the air-fuel mixture? If so should I replace the carburetor, and what carburetor would you guys recommend?

Hoping to get this motorized bike project up and running as soon as possible!

good job on the attempts to get it running but when gas gets gross it blocks those tiny jet holes buy a micro drill set / wire gauge drill set and drill out the jet keep the same size then go up one

 

[hazmat]

UPDATE: So I took the carb apart and it doesn't look good. From the looks of the fuel bowl there's this flaky almost muddy deposit that's forming. This residue was on the jet as well (pictures below). Not even 3 weeks ago I cleaned and disassembled the carburetor. Could this be causing the jet to get clogged and not let in fuel? I'm trying to think where this is coming from, fuel tank or the fuel filter?
View attachment 81455

Here's the picture of the jet, as you can see it looks like that residue is on the the jet as well. I took a small bread tie, stripped it to the wire, poked it in the jet and freed anything blocking it. I tried to unscrew the jet counterclockwise and it won't budge so I'm not going to try. Don't want to chip another piece off of the brass.
View attachment 81456
View attachment 81457

I managed to clean and reassemble the carburetor. Now all that's left to do is put a new piece of fuel line leading to the fuel intake on the carb as it has a leak.
I'm trying to figure out why the deposit is forming and what it could be from. I'm not sure if it's from fuel sitting around as I put fresh fuel in the tank and it's been sitting for less than 3 weeks since the last carb clean.

old gas even looks prematured gum what kind of gas do you use

 

[Deleted member 25783]

Drop a Gear, It's good to hear a happy ending with these Hua Sheng engines. Before I painted my gas tank, having read about the rust and grunge inside the tanks. I loaded the tank with BB's and denatured alcohol and shook the tank for a good long time. Dumped the BB's and rinsed several times. But now as I am experiencing similar trouble you have given me a good place to start. I have to make it a reliable runner as I mean to sell it or gift it to a grandson for transportation while attending college.
Tom from Rubicon, WI

 

[Member 28661]

good job on the attempts to get it running but when gas gets gross it blocks those tiny jet holes buy a micro drill set / wire gauge drill set and drill out the jet keep the same size then go up one

Thanks! Yeah I came to the conclusion that the culprit of it was the cheaper 87oct gas and the gas is of poor quality. Was thinking it might be the fuel tank, but the fuel filter is spotless. Next tank fill up I'm going to try 90oct and see how it works. If the motor doesn't want to start up in the future, I'll drill the jet slightly larger.

 

[Member 28661]

old gas even looks prematured gum what kind of gas do you use

Unfortunately I think that's the case as well. I'm, using 87oct currently. However I think it's of poor quality so I'm going fill the tank up with 90oct next time. I'm using about an 1oz-2oz of seafoam as well to help prevent this premature guming of the fuel, but 90oct is probably my best bet.

 

[Member 28661]

Drop a Gear, It's good to hear a happy ending with these Hua Sheng engines. Before I painted my gas tank, having read about the rust and grunge inside the tanks. I loaded the tank with BB's and denatured alcohol and shook the tank for a good long time. Dumped the BB's and rinsed several times. But now as I am experiencing similar trouble you have given me a good place to start. I have to make it a reliable runner as I mean to sell it or gift it to a grandson for transportation while attending college.
Tom from Rubicon, WI

I know right! I was getting really worried when it wouldn't start up after cleaning the carb. Turns out it was just a clogged jet and some premature fuel gumming. The fuel gumming is most likely from the cheaper 87oct fuel I've used, going to switch to 90oct the next refill. There's hope for these HuaSheng 142f motors!

I should have cleaned and treated my gas tank prior to having installed it, like you did. But I'm going with a machined aluminum fuel tank in the near future.

If you're having similar problems I would highly recommend pulling apart the carb and cleaning every nook and cranny with carb cleaner. And most importantly take a small metal wire and poke it in the jet; I stripped a bread tie to the wire and used that. It will release any debris there.

Best of luck with your bike!

 

[Member 28661]

Quick clip of the motor running. Looking for tuning advice at the moment. The idle looks and feels good. However when throttle is added the engine bogs a little bit then sounds normal. I'm 3.5 turns out for the A/F screw and 1-1/2 in for the idle screw. I'll tune the engine further when I install the chain tensioner and I'm able to ride it. I just want to get a base tune down. Or will this tune suffice?

Also you can see in the video the chain going to the freewheel is incredibly loose. It's not loose enough to take a half a link out unfortunately. Going to get a chain tensioner installed on it asap.

 

[Member 28661]

I think I'm satisfied with the idle and the tune at this moment. Keep starting up the bike every 2 days or so to keep fresh fuel in the fuel bowl. As well as have the motor run for a few minutes.

The current problem I'm running into is the loose chain going from the jackshaft to the freewheel (pictured below). It's the only thing left preventing me from riding the bike. The chain is quite loose, enough to cause teeth skipping and noise. Also it may even throw the chain , definitely not good! So i'm not riding it until it's fixed.

This is when the chain is tight. (picture below)

I'm not sure if this is the right thread to continue this on or if I should post this in another part of the forum, let me know.
Currently I'm looking to create or find a chain tensioner that would be able to keep this chain tight. I've been speaking with Jim over at Sick Bike Parts and talking about using the Right Side chain tensioner for this project http://sickbikeparts.com/chain-tensioner-right-side/ . However I'm not sure if this would work for this bike and he agrees. As you can see in the pictures above and from the product photo for the chain tensioner from Sick Bike Parts. The chain tensioner is supposed to be placed below the output sprocket of the jack shaft. It's made for the 2 stroke shift kit, while mine is the 4 stroke shift kit. So there isn't much metal to drill a hole for the bolt or the chain tensioner. Does anyone know of any good DIY or prebuilt motorcycle chain tensioners for example that would work well for this situation?