I have a 05 650 V2, I cant get to run right, It idels good but try to drive and get a max of 10km/hr, I removed the air box cover and my Vacuum pistons do not move when i rev up the engine, I have removed the diaphragm & needles & every thing looks good, No crack or holes, I read on a previous post that there is a seperate vacuum hose that goes to the side of the carb but am unable to locate.

 

Put your hand over your snorkel once and try. If no luck there, try putting stock cdi back in, and i would suggest running a can of seafoam through it. You can dump a little of it VERY slowly down the throat of the carb while its running, and expect a little smoke from the exhaust, thats normal. Dump the rest into your gas tank. Just a few easy checks.

 

It sounds like you are in limp mode. but I will tell you that it wont run with the air box lit off. It will idle and that all.

 

it does run with the airbox lid off, when ideling or when i rev it up, there is no backfire at any time. but my vacuum pistons in my carbs dont move not letting air into the engine.