Huasheng 49cc wont run without some choke

[blackmarkus]

my Huasheng 4 stroke engine dies when i turn off the choke fully. It runs ok with a little choke. I have spent a few hours looking for an answer on here but only got a few ideas. anyway I think that there must be a air leak in carb or jets need drilling. Someone here must have found a quality replacement carb for this engine or a fix ??????????

This is probably about my 30th build but it is my first 4-stroke build. This site has helped me alot in the past with the 2-strokes so hopefully someone has my answers.
Cheers

 

[Quenton Guenther]

Hi blackmarkus,

Most likely the passages are retricted. The most common cure it to clean carburetor, sometimes after the motors are test fired a small amount of gas remains behind and evaporates leaving a partly blocked passage.


I would suggest removing the float bowl and taking a look for evidence of dried gas residue.

I alway use a little liquid Gummout carburetor cleaner in about every 5th tank of gas to keep the small jets clean.

Also be sure the choke is turned off, not on, as this is a common mistake.

Have fun,

 

[blackmarkus]

how embarrasing

took air cleaner off and yes i was operating choke back to front . so i relased some tension off the throttle cable,reset the idle and it's running sweet.
thanks

 

[Barry]

HS 5G 4 stroke

Hello,
I just finished my first 4 stroke project as well and have the same problem. There is no mixture control needle on my carb, only an idle stop adjustment. That said, mine starts on the first pull using full choke and I just run it using 1/2 choke which has been working fine for me.
Barry

 

[Quenton Guenther]

The biggest issue with all motors used for motorbikes concerns "dirty fuel". About 90% of the time the coating around the gas cap loosens while removing or installing the gas cap.

To avoid serious problems, simply remove the coating around the cap, clean the tank, then install.

Another issue on the 49 CC HS motor is the location of the pilot jet. Often the jet is over looked and when stopped up can cause a lot of problems [choke must be on, won't idle, won't take gas, etc]. The pilot jet is located below the idle adjustment screw[black plastic], and is easy to remove. Simply remove the idle adjustment screw, and lift up the jet with a small screwdriver. Be careful to keep track of the small "O" ring at the base of the jet fixture. DON'T use a drill bit to clean the jet, instead use a piece of fine wire [I use part of a broken throttle cable].

It is wise to use carburetor cleaner in about every 5th or 6th tank of feul to keep the small passages clean.

Have fun,

 

[rawly old]

Yea, I've got an HS power problem. I mounted a new HS to a belt drive
setup that's been working just fine with a GX35, but I wanted more power.
Running the HS static on a stand it revs right up to 6k no load at half
throttle. Yet when I get on the road it stalls at 4k no matter how slowly
I power up. At first I thought I was flooding it, but now it seems to just
lack the power to go further. I don't get it. It should have 60% more power
than the GX35, but it's not performing half as well as the honda???
What do I need to do?

 

[Barry]

HS Carb

I'm wondering if there is an aftermarket replacement carb that will fit the HS?
Barry

 

[Quenton Guenther]

Hi Rawly Old,

Still sounds like a carburetor issue. I would remove any oil sensor, disconnect the kill buttion, and remove the air breather filter during testing. I have seen a kill button short out at higher RPMs. I know for a fact the oil sensor [only used on the Honda 50 motors] will shut the motor down at higher RPMs and leaning over during sharp corners.


Which drive system are you using?

Have fun,

 

[rawly old]

I'm using a DYI belt drive that performed well with the GX35. Since
it's a rear mount, I went to a diaphragm carb. It revs like a bat outa
**** no load, I just don't seem to be getting any torque? I tried easing
the belt tension which helped a bit, but it's still pretty gutless for some
reason? I leaned the carb a bit with no appreciable improvement. I'm
stumped. Will try your suggestion.

 

[rawly old]

Well Quenton,
You called it; There was just a micro hair of exposed wire at the
connecter for the kill switch touching the U-bracket. I'da never found
it if I hadn't been looking for it. Didn't short enuff to keep it from
running, it took just enuff power to stop it pulling. It seems to still
need some tweaking, but it pulls a whole lot better now and should
improve with break-in. Sorting out the best belt tension and carb
setting outa do the trick.

THX