I know exactly what this issue is, having dealt with myself. The problem lies with the actual brass seat for the float need. this is held in place by a small screw which is located the edge of the seat. When the actual brass seat is removed you will see there is a O ring located in a groove on the outer circumference of seat and this where the problem lies. This o ring will let fuel enter the float chamber, bypassing the float needle and will flood the carburetor. These carburetors, due the emission regulations do not have overflow tubes to release the excess fuel that is entering the float bowls but will allow the fuel to rise up through the main jet and flood the relevant cylinder. This will cause a hydraulic lock in the cylinder and also allow fuel to seep through the exhaust valve into the muffler. This problem is most prevalent after the engine has been sitting for extended periods which allows the o ring to dry out and shrink ever so slightly. A word of caution, trying to crank the engine when there is a hydraulic lock has the potential to bend a conrod. The good news is that the o ring issue is a very inexpensive fix. However, were you to say bend a conrod, that would not be an inexpensive fix.
Why go from a carbed bike that gave you trouble to another carbed bike that could possibly give you the same issues? Get a bike with fuel injection like the VStar 950, problem solved🤷♂️
I know exactly what this issue is, having dealt with myself. The problem lies with the actual brass seat for the float need. this is held in place by a small screw which is located the edge of the seat. When the actual brass seat is removed you will see there is a O ring located in a groove on the outer circumference of seat and this where the problem lies. This o ring will let fuel enter the float chamber, bypassing the float needle and will flood the carburetor. These carburetors, due the emission regulations do not have overflow tubes to release the excess fuel that is entering the float bowls but will allow the fuel to rise up through the main jet and flood the relevant cylinder. This will cause a hydraulic lock in the cylinder and also allow fuel to seep through the exhaust valve into the muffler. This problem is most prevalent after the engine has been sitting for extended periods which allows the o ring to dry out and shrink ever so slightly. A word of caution, trying to crank the engine when there is a hydraulic lock has the potential to bend a conrod. The good news is that the o ring issue is a very inexpensive fix. However, were you to say bend a conrod, that would not be an inexpensive fix.
Ran into this same problem with my V Star 1100.
Even with new needle and seat assemblies I always close the petcock when parked just to be safe.
I live at 6000 ish feet and changed my stock 90 jets to 86 on my 650. She run great now
That bike should have stock jets With that set up low speed 17.5 primaries 115f-117b.
Why go from a carbed bike that gave you trouble to another carbed bike that could possibly give you the same issues? Get a bike with fuel injection like the VStar 950, problem solved🤷♂️
You’ll have to ask the guy that did the trade. I’m pretty sure he doesn’t even have the 650 anymore, think he traded it for a boat or something, lol