I'm losing all hope. It must be the intake valve, or even something bigger

 

Do a compression test if it hasn't been suggested already

 

That was sand that had gathered on top of the head over time and you had to get rid of that before you took the plug out? Or was like attached the spark side of the plug??

FYI

 

That vid should give you a very good idea of how the diaphragm on the slide uses vacuum to lift the jet needle and that the butterfly connected to the throttle cable is what regulates airflow into the engine. If the diaphragm isn't sealing or is damaged, the slide and jet needle won't raise and the carb will behave like it is being choked. Another simple test to check the function of the diaphragm would be to remove the rubber boot between the airbox and the carb, start the engine and rev it. The slide should open as engine speed increases-it may not open fully but you should see it open. If the slide doesn't move then there is a problem with the diaphragm or the internal air passage to the top side of the diaphragm is blocked.

 

Maybe someone who has a CV carb can jump in here. If you have the boot off and twisting the throttle wide open, as the bike is parked, will the slide lift all the way?

I am having a hard time understanding the diaphrams action. With the wide open throttle (butterfly), the pressure differential from the air box side to the valve side can't be that much. Seems like the highest diff would be when the engine is just off idle, therefore raising the slide wide open> I think it is more complicated than that illustration, specifically the detail of how the port is installed in relation to the butterfly.

 

Engine load hugely factors delta V across the carb. Running it on the stand vs. under load will greatly change how the slide reacts. You never tune a carb on the stand, make your adjustments and run it on the road.

 

Okay, new problem. For 5 seconds that thing ****ing HAULED, so that problem is fixed. Came to a stop to turn around now every time I give it gas the motor decelerates.

Some more info, the throttle butterfly does work correctly.

It also idles fine with choke and without


Start at 1:40

When Im traveling back the bike has the choke on and I gave it no gas but left the clutch half out

 

Yah, sand is no good. Worn valves, blown rings, f'd up crank bearings. Did you change the spark plug at least after discovering it was caked with sand??

 

Yup cleaned it out and changed the plug and none of the sand actually got into to cylinder, did you watch the video?

 

So, you're saying there was sand on the OUTSIDE of the spark plug, down there in the spark plug well? Common. Road grit and dirt will collect in the well. Always try to blow the plug well out with compressed air before pulling the plug.

Are you out of fuel? Just checking . . .