Air leak?

[LunchMoney]

Today i mounted a new carby on my engine, a delorto sha clone from aliexpress. It ran very rich from the start but i thought i could warm it up a little and it could lean out. Was 4 stroking for like 25 minutes but ran good when climbing hills. Got it nice and hot and it was perfect. Decides to stop for a bit and noticed when i pull in the clutch, the idle slowly comes down and the engine dies. Okay, i needed to get gome somehow. So, back on the road. It 4 stroked for like 5 minutes and started to run amazing. Saw a straight road and decided to test the max speed. Got to about 50km/ph and suddenly the engine started to stop on it's own.
Is it an air leak? I know it is definitely not near the intake. Can air leak to the engine thru the exhaust connection?

 

[Greg58]

Doesn’t sound like an air leak, it sounds like fuel starvation. At wide open it sound like the bowl is running out of fuel. I know it’s no comparison but I had a GTO with three two barrels that did the same, a electric fuel pump cured it, more fuel should help yours.

 

[Greg58]

Check the gas tank cap vent, if it doesn’t let air in fuel flow to the carb will be slow.

 

[GW's Motorized]

Sounds like your idle jet is way too rich as well as fuel starvation up top.

 

[DAMIEN1307]

Sounds like your idle jet is way too rich as well as fuel starvation up top.

Now all we need is for someone with experience with this type of carburetor to come along with some suggestions as to how to tune this type of carburetor properly for @LunchMoney...lol.

 

[GW's Motorized]

Now all we need is for someone with experience with this type of carburetor to come along with some suggestions as to how to tune this type of carburetor properly for @LunchMoney...lol.

Yeah, we can all tell him what he needs to do, but not how to do it

 

[DAMIEN1307]

Yeah, we can all tell him what he needs to do, but not how to do it

But we DO help people by telling them how to do it Gordy...lol...Have you been sleeping in class again when I help people tune their NT's and BoFengs???...lol.

 

[LunchMoney]

Yeah, i know this jet is crazy rich, i'll set it smaller, but why does it not idle after getting upt to operating temps and why does it starve fuel? The vent is okay

 

[LunchMoney]

Or can i fix it by making it smaller and maybe it won't starve that much?

 

[LunchMoney]

It idles great when it's cold