49cc HS engine keeps stalling

outlawbiker

Member
Mar 15, 2009
282
0
16
Chicago NW Suburbs
I got another one of those 7g ghost racer kits from gasbike, choke lever was broke and trans cover was cracked, sent off for the parts to fix it, installed it into a kent del rio and from the start it seemed like it was starving for fuel or air.But it would run and wouldnt stall out so, no big deal i thought for the first couple of weeks and it seemed to go away.

The day i get a buyer to pick it up,it wont stay running unless its choked, as soon as flip the choke off it dies and i cant get it running again unless i choke it. Fine, im thinking vacuum leak right?

Today I pull the carb off and put gas resistant RTV on all the gaskets thinking that will solve the vacuum leak...... nope. I check the fuel from the tank to the carb and its free and clear.

If i am able to keep it running with the choke off as soon as i give it some gas it dies, same thing with the choke on. the only thing i didnt do was check the float,but i thought if the float was stuck open gas would pour out of the overflow tube and thats not happening so i ruled it out. Maybe im wrong, but before i get anymore pissed about this I thought id throw it out there to you guys.

Any ideas whats going on?
 

outlawbiker

Member
Mar 15, 2009
282
0
16
Chicago NW Suburbs
what's the plug look like?
plug is black,pulled the plug out cleaned it up and tried tweaking the mixture screw under the brass plug, no luck.still stalling and fouling out the plug.

I ordered a new carb just incase,I know i could break down the old one and try to clean it, but i wanted a back up. Its been too hot today to tear into it.

Just want to get this bike done and get rid of it, its been bad luck from day one.
 

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
4,484
16
0
memphis Tn
The carbs on these motors are famous for this problem.
Best fix is swap for NT carb/manifold or better quality Walbro pumper carb
 

outlawbiker

Member
Mar 15, 2009
282
0
16
Chicago NW Suburbs
new carb fixed the problem,sort of. I cant get it to stay running at idle without the clutch trying to grab. Im not worried, I just want to get this bike out of my garage and get working on other stuff.
 

Jcs1989

New Member
Jul 31, 2016
37
0
0
Alabama
Check an make sure your fuel line is tight on the carb an the petcock from the tank. I have mine zip tied so there is chance of air getting in. Hope this helps..
 

outlawbiker

Member
Mar 15, 2009
282
0
16
Chicago NW Suburbs
The carbs on these motors are famous for this problem.
Best fix is swap for NT carb/manifold or better quality Walbro pumper carb
This got me thinking of a carb swap on another bike, How would you go about getting one of those Walbro's to work on a HS 4 stroke? Thought they needed some kind of back pressure to get the pump in em to work. Forgive my ignorance,but ive never worked with one of those Walbro's before, only know of them by skimming these forums for ideas and learning a few new things.
 

BikeSmith

New Member
Nov 28, 2015
15
0
0
North Dakota
You may have the same problem I just faced. a bad fuel cap. Mine was not venting, it would start on the choke and die just like yours. try taking the fuel cap off and start it. worked for mine, so I just blew out the vent hole with some compressed air and good as new.
 

Torriatte

New Member
Aug 17, 2020
1
0
1
50
I have similar issue. Brand new 4 stroke engine....ran great for a few days....then suddenly won’t stay started, and giving it gas has NO effect. I though it was the carb....or possibly broken flywheel. No...the problem is this new “upgraded” gas tank they put in my kit. It has the threads externally, rather than inside. So now on the petcock valve there is a bolt that affixes the spout rather than the spout being physically screwed into the tank. PLEASE keep in mind how difficult it is to not make jokes when using words like petcock and screw.

Anyway.... I found that my valve was crap, and the externally attached bolt had separated from the tube that goes into the gas tank.
There was literally just a drip of gas at most making it down into the line. The petcock SUCKS....another missed joke....but essentially the valve is garbage. I had to order another one on EBay for $8.00.

So although it looked like it was getting gas...it was not. And YES I had the valve open.
So check your fuel valve, and check your fuel filter. Those can SUCK too.
 

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Gerard jones

New Member
Aug 25, 2020
20
5
3
68
I have similar issue. Brand new 4 stroke engine....ran great for a few days....then suddenly won’t stay started, and giving it gas has NO effect. I though it was the carb....or possibly broken flywheel. No...the problem is this new “upgraded” gas tank they put in my kit. It has the threads externally, rather than inside. So now on the petcock valve there is a bolt that affixes the spout rather than the spout being physically screwed into the tank. PLEASE keep in mind how difficult it is to not make jokes when using words like petcock and screw.

Anyway.... I found that my valve was crap, and the externally attached bolt had separated from the tube that goes into the gas tank.
There was literally just a drip of gas at most making it down into the line. The petcock SUCKS....another missed joke....but essentially the valve is garbage. I had to order another one on EBay for $8.00.

So although it looked like it was getting gas...it was not. And YES I had the valve open.
So check your fuel valve, and check your fuel filter. Those can SUCK too.
That doesn't make sense, the engine should run on the fuel in the bowl until its gone.
I've driven mine to the store, had the engine fade out and die, then I realize I drove it there with the petcock closed.