I just put a new sky hawk engine on my bike. Got it fired up and it runs good. I just can't figure out why the carb is spewing gas out the bottom vent tube. This is my first ever build and I'm trying to get it running for my cousin. Thanks all
Carb leaking gas out vent
- Thread starter the hoove
- Start date
zip tie that vent to the top of the carb mine did this to the CNS V3 EPA carb is a pain in the but
if you didnt flush out gas tank,most likely a little debris made it into your carb.
i had to clean my tank a couple times.
removed the two screws and took off the bowl and cleaned the needle and seat.
cured it.
its my understanding some carbs may have little bits caught in them,best to check and clean them before installing.
i had to clean my tank a couple times.
removed the two screws and took off the bowl and cleaned the needle and seat.
cured it.
its my understanding some carbs may have little bits caught in them,best to check and clean them before installing.
I put the filter in the gas tank befor filling it. What do you.guys use to clean the tank out? Also, the bowl is at the bottom of the carb correct. Sorry new to worki g on carbs.
I will echo the comments that perhaps you have some debris from the tank playing he11 with your carb, the tanks usually have all sorts of crap in them when new. I would recommend you add a quality in-line fuel filter to make sure nothing gets into your carb. You also need to make sure the filter in the top of the fuel valve (that goes inside the tank) doesn't get clogged....
As for the reason for the fuel overflow, it is most likely float/needle valve related. The needle valve in the carb is the device that cuts off the flow of fuel into the bowl, if some debris gets caught in the needle valve and props it open then fuel will overflow from your carb. A simple cleaning of the carb and installation of an in-line fuel filter will fix this problem. Make sure you clean all three jets when you clean the CNS carb, the idle and enrichment jets are pretty small and clog easily, if the idle jet is clogged you will have a hard starting motor and your low end speed will probably be pretty jerky...
If debris in the needle valve is not the problem, and the carb still overflows, then you probably need to do a float adjustment. The float is the device that pushes up on and closes the needle valve when the proper amount of fuel is in the bowl. If the float is improperly adjusted it may never close off the needle valve and allow the carb to overflow. There is a small metal tab on the float that pushes up on the needle valve to close it, bend this tab slightly so it pushes the needle valve up further to fix this problem. If you clean out all the fuel from the carb and use some clean fuel line, you should be able to blow on the fuel line and it should flow freely when the carb is sitting upright, when you flip it upside down you should feel the flow being blocked off. This was helpful to me in getting my float adjustment into the proper ballpark...
As for the reason for the fuel overflow, it is most likely float/needle valve related. The needle valve in the carb is the device that cuts off the flow of fuel into the bowl, if some debris gets caught in the needle valve and props it open then fuel will overflow from your carb. A simple cleaning of the carb and installation of an in-line fuel filter will fix this problem. Make sure you clean all three jets when you clean the CNS carb, the idle and enrichment jets are pretty small and clog easily, if the idle jet is clogged you will have a hard starting motor and your low end speed will probably be pretty jerky...
If debris in the needle valve is not the problem, and the carb still overflows, then you probably need to do a float adjustment. The float is the device that pushes up on and closes the needle valve when the proper amount of fuel is in the bowl. If the float is improperly adjusted it may never close off the needle valve and allow the carb to overflow. There is a small metal tab on the float that pushes up on the needle valve to close it, bend this tab slightly so it pushes the needle valve up further to fix this problem. If you clean out all the fuel from the carb and use some clean fuel line, you should be able to blow on the fuel line and it should flow freely when the carb is sitting upright, when you flip it upside down you should feel the flow being blocked off. This was helpful to me in getting my float adjustment into the proper ballpark...
I flushed my tank out with water before I used it and used a microfiber rag on a coat hanger wire to get the last bits out and dry it out a bit, then let it sit overnight in front of a fan to dry. If you're already mounted then maybe drain the tank then remove the filter from the valve and run the fuel through the tank a couple times, letting the debris settle out of the gas so you don't poor it back into the tank. I recommend you eliminate the in-tank filter and add an in-line filter instead. They filter better and you can see the fuel flow through them, as well as any debris that may collect in them.
Yes, the "bowl" is the bottom of the carb which is where the fuel is held. The float sits in the bowl and floats up on the fuel, when floating high enough the float tab pushes the needle valve up and closes it, which stops the fuel flow. Its a rather simple little mechanism with only a few parts....
Awesome! Thanks guys! I will be doing this for sure. Just gotta pick up a couple of things then. When I have time I will show you guys the sprung tensioner I wielded up to the frame as I have had tension issues with the chain. All kinds of fun getting this bastard running
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Just one more question? If the carb is tilted more than say 15* will it cause this issue as well? The orientation of the motor has it tilting down a bit. And I think it is causing fuel to overflow out of the bottom vent tube.
Yes, if the carb is tilted and float is adjusted to keep the bowl rather full it could cause an overflow problem. A small adjustment to the float can fix this, bend the tab on the float so it closes the needle valve when it is lower in the bowl...