vac caps blowing off wtf?

took one hell of a mntn ride the other day and when i stopped i noticed my vac caps all blew off my carb boots. wtf are my valves out and back feeding or something?

that was my first thought. Were they newish or old and dry-rotted. May have just fallen off one at a time from being old and falling apart. Unless you checked them recently, can't say that's something I'd be likely to notice until I was in there doing something else. I'd think you'd notice a difference in how it runs when that hapenned.

Yea i was noticing alot of idle fluctuation i had to keep fiddling with it and i noticed they were most all off. some lying around plugs. maybe hard downshifts and engine braking?

www.z1enterprises.com/ItemDetails.aspx?i...plugs&item=KL11-4972

Good Fortune!

could be a weird one. I'd try replacing them with new ones and see if it happens again. If it keeps happening I'd be inclined to check for leaking intake valves, not sure what else would allow that much pressure to end up in that region.

I used some caps I got at the auto store. Before too long they cracked and fell off. Then I bought some caps from Z1 and no more losing caps.

Same happened to me two days ago (didn't lose them, but they were pushed out a notch) - aren't they supposed to be "sucked in"? Had the same thought as lushbaugh (blow back), but bike (1978 KZ650 - stock with air box - rejetted for 4in1) ran great - didn't notice a thing...

Maybe your guys engines are running backwards. :laugh:

I bought my replacement caps at ACE Hardware. They are vinyl and work great.

Clean the "nipples" and inside the caps with alcohol or some other volatile cleaning fluid like acetone. Let dry completely then spray the insides of the caps with hair spray. Slide the caps on before the hair spray dries. The caps will then be glued on and wont come off until you give them a little twist. This also works on handlebar grips that won't stay put.

Sounds like the carbs are "sneezing" or "spitting back" at idle or off idle. This is caused by a too lean condition. You might try opening your idle air screws a 1/4 to 1/2 turn.

Could also be a problem with the ignition advance. Clean and lube it then check your timing.

kaw-a-holic wrote: I bought my replacement caps at ACE Hardware. They are vinyl and work great.

X2, fit much snugger than the stock ones.