49cc 4 stroke will not run without some choke.

[Gerard jones]

Hi guys, first timer here.
I ran this bikeberry 49cc very nicely until it injested rust or dust from the tank, it clogged the carb, I clearned it out and it ran ok but I still noticed black dust in the fuel line. I installed a better filter and rinsed the tank out, no more junk in the line but now it won't run without some choke.
Today I pulled the carb again and ran wire thru the jets and blew everything out with compressed air.
Painted the used gaskets with some indian head gasket shellac, still no dice, only runs with half choke, wont idle and won't take gas or rev up once choke is off it just bogs down.
All the youtube videos infer this to be a fuel starvation problem, makes sense considering it ate dust but I can't get the jets cleared, I pulled the float jet and idle jet on the carb exterior. Not seeing any clogs but there are jets I'm sure that can't be seen.
I replaced the chinese plug with NGK , no difference.
Fuel is good, fires right up with choke but then revs way up high even at low throttle with the choke engaged.
Turn the choke off and rpm drops to idle , then dies, it will only recover if I apply choke again.

I'm thinking to toss in the towel and get another carb, this might have crap where I can't remove it.

Any other suggestions?

 

[Gerard jones]

Solved, I installed a NT carb, its a bit lean at the top end but that can be easily fixed when I get some jets to try.
Idles perfectly, very easy to adjust this carb, much simpler to clean. Rode it for an hour without problem.

I did a full autopsy on the original carb, drilled out the welch plugs to expose idle adjust screw and found nothing, no clogs, ran wire through the newly exposed ports, no dirt.
Without any regret I tossed it in the dumpster. Success can't be beaten.

Now if I didn't break my chain today..

 

[Choochoo_nesby]

I had similar issue, was dirt in the carb. I have seen several people on here suggesting the NT carb, I had a 2-stroke before and had a lot of problems, so as long as this works I am not changing anything. I finally have my second bike running right, now to work on my first bike. Have fun, and be prepared to buy plenty of spare parts.

 

[Gerard jones]

I had similar issue, was dirt in the carb. I have seen several people on here suggesting the NT carb, I had a 2-stroke before and had a lot of problems, so as long as this works I am not changing anything. I finally have my second bike running right, now to work on my first bike. Have fun, and be prepared to buy plenty of spare parts.

the original huasheng? carb was ok when it worked, then got crap from the tank in it and was never right again.
I found 3 gaskets just made it a pain to work with,
the NT carb only has 1 gasket, no plastic spacers etc.
Huashang idle jet is concealed behind a blank welch plug, you can't adjust the mix without drilling out the welch cover.

 

[curtisfox]

Huashang idle jet is concealed behind a blank welch plug, you can't adjust the mix without drilling out the welch cover.

That is how they get past the emissions standards, a lot of newer engines don't even have a adjuster screw...........Curt

 

[Citi-sporter]

Aren't these little Huangsheng carbs one of the simplest carbs sold for a small engine?

They have a main jet circuit and an idle circuit, right?
Gravity feed from the fuel tank and float bowl and the float needle?

Do any off you folks add a gravity feed carb fuel filter into the line from the tank to engine before you start your engine for the first time??

If you can't get into the idle circuit because of the welch plug, it's generally easy to remove the plug with a tiny drill and a sheet metal screw. Until you get into the idle circuit, remove the idle metering screw and figure out where to place carb cleaner hose to blow the dirt free, these otherwise easy to fix carbs are just going to become paperweights.

That's wasteful..

 

[Gerard jones]

Aren't these little Huangsheng carbs one of the simplest carbs sold for a small engine?

They have a main jet circuit and an idle circuit, right?
Gravity feed from the fuel tank and float bowl and the float needle?

Do any off you folks add a gravity feed carb fuel filter into the line from the tank to engine before you start your engine for the first time??

If you can't get into the idle circuit because of the welch plug, it's generally easy to remove the plug with a tiny drill and a sheet metal screw. Until you get into the idle circuit, remove the idle metering screw and figure out where to place carb cleaner hose to blow the dirt free, these otherwise easy to fix carbs are just going to become paperweights.

That's wasteful..

mine came with a filter in the tank and an inline filter, dirt got past both filters and was visible in the fuel line.
I removed the welch plug and needle, blew it out, didn't find any clogs.
I dont know what the problem was and just tossed it.
it might have been a gasket.
theres the air filter, a gasket, carb and a second gasket, plastic spacer and third gasket.
lots of opportunity for vac leaks.

the NT carb has only one gasket.
you can't beat success.

 

[curtisfox]

a filter in the tank and an inline filter Both China junk, clean and replace before use.

second gasket, plastic spacer and third gasket. All needed on 4 stroke, plastic spacer is for heat blocking to prevent vaper-lock............Curt

Lot of guys have good luck with them, and like said simple and easy.

 

[Citi-sporter]

Briggs makes a decent enough fuel filter for their smaller engines the little red colored gravity feed in-line fuel filter. I've never had issues with their filters. The tiny fuel filters made by Purolator aren't bad either.

 

[Citi-sporter]

a filter in the tank and an inline filter Both China junk, clean and replace before use.

second gasket, plastic spacer and third gasket. All needed on 4 stroke, plastic spacer is for heat blocking to prevent vaper-lock............Curt

Lot of guys have good luck with them, and like said simple and easy.

The built in strainers on the 2~2.5 liter CG engine peanut tanks are actually a finer grade of mesh than the strainers on 1960's-70's Italian motorcycles like the bevelgear head Ducatis. You wouldn't believe what would pass downstream of the strainers on the old Ducati single's tanks.

 

[Gerard jones]

Briggs makes a decent enough fuel filter for their smaller engines the little red colored gravity feed in-line fuel filter. I've never had issues with their filters. The tiny fuel filters made by Purolator aren't bad either.

Briggs filter is what I have now, the paper filter that came with the bikeberry kit was passing tank rust.
The in tank filter had fallen off and was rattling around in the tank.

 

[curtisfox]

The built in strainers on the 2~2.5 liter CG engine peanut tanks are actually a finer grade of mesh than the strainers on 1960's-70's Italian motorcycles like the bevelgear head Ducatis. You wouldn't believe what would pass downstream of the strainers on the old Ducati single's tanks.

Thing of it is there is junk in the tank to begin with, even new the need to be cleaned.........Curt

 

[Gerard jones]

Thing of it is there is junk in the tank to begin with, even new the need to be cleaned.........Curt

yeh I got that memo too late.
By the time I traced it to the tank and flushed it, reinstalled the in-tank filter and better fuel line filter the carb was clogged good.
Then removed and cleaned the carb 4 times before finding the hidden needle, by that time I already installed the NT carb and it ran perfectly.

 

[Citi-sporter]

I must be the exception to the rule. I bought my one and only 48cc CG bike engine back in spring 2018 and was expecting the tank was going to need an Oxalic acid treatment to get rid if the rust scale, and a big flushing to clean out the garbage that most buyer encounter in these tanks.

And the bike engine I bought a cheap one too! It was a Amazon $107 cheapy.

When it arrived, the fuel tank was the first part I inspected because it had a small dent. And yet it's inside was bright, shiny and clean steel, not a spot of internal rust, and I flushed it with a quart of denatured alcohol for a full day. Not much crud if any was present in the alcohol. So I mounted the tank and engine up after prepping and putting on a PW50 carb and a new B&S red filter. I've had the float bowl off the PW twice to solder up the main jet to run a little leaner and I've found no debris in the float bowl.

Ever..

I tell you what though, the outside of that fuel tank started paint blistering and rust spotting over our last wet winter and I had to give it complete wire brushing and a heavy coat of black Rustoleum enamel in a can. Hopefully the paint doesn't blister any more.