Post-carb cleanout & float adjustment, no start

[Aweebaweeba]

Update: I believe there's still too much fuel going through, because it floods very bad on the choke (black spark plugs) and won't stay running for long with the choke off. It seems like it wants to start, but the minute I give it gas the rpms plunge down and it dies. Is this an air/fuel mix screw problem (currently it is set at 3 turns from seated position)?

I'm going to be replacing the vacuum line hose with something more heat resistant. Also a note about the varnish seen in the pic: the tube was CLEAR before I had gone out for a spin, now it's all gunked up.

I now have a sneaky feeling that the petcock is broken because I nudged it pretty hard trying to get the fuel line off. We will do Gary's test to confirm the suspicion... if it is broken, will the rebuild kit suffice or should I get a new one altogether? All of the petcocks on mikesxs are non-vacuum types... Oh and another thing! The three positions I have on the petcock are PRI (3 o'clock), ON (6 o'clock) and RES (9 o'clock), this seems weird to me, because the ON position actually cuts the fuel off.

 

[5twins]

I think your carbs and petcock both need rebuilding, or at least a complete disassembly and cleaning. I don't know where guys get the idea they can buy 30+ year old bikes, hop on them, and just ride off into the sunset without having to do any work to them, lol.

Your petcock is vacuum operated. It should not flow any fuel in the "ON" or "RES" position unless a vacuum line is connected to it AND the motor is running to provide that vacuum. In the "PRI" position, it will flow any time. That position bypasses the vacuum part and just flows straight through like an old style manual petcock. If you buy a manual replacement petcock, you will need to cap over the vacuum nipple on the carb manifold. It will suck air and lean your mix way out if you don't. The bike will run like crap which you've already noticed when that vacuum line came off.

 

[xjwmx]

The vacuum tube is usually connected to the left side barb rather than the right like it is in your picture. The right side usually has just a cap on it. Neither side should be open. That clear tube will melt as soon as it touches the head, and it will. Then you will have an air leak, but it won't matter because you won't have any fuel flowing