Carb Question about the Jets & Diaphram

[Old Geezer Richard]

 About how fast or at what RPM's do the slow jets fade off and the high speed jets kick in ? and also , what do those rubber ( neophrene ) like diaphrams under the carb caps do ? what is their specific job during the carb operation ... I'm trying to trace down what the problem is when I run my " Old Fat Lady"  thru the gears and as I'm getting up towards the 5,000 RPM mark it hesitates and won't go any faster ... my plugs are showing a nice coffee / cream sandy brown color . it picks up good , just mildly running thru the gears and it will acclerate going up thru the RPM range until I'm getting up to that 5,000 level ..  Just curious ....  Thanks the Geezer

[98valk]

slow jets affect small throttle position movements at WOT.
but this is usually the range of each circuit
idle-0 throttle - idle mixture screw
0-1/4 throttle - pilot jet
1/4 - 3/4 - needle
3/4 - WOT - main jet

all over lap somewhat and affect each other some.

go to factorypro.com at top row click on product support, then on CV carb tunning. also scroll down to "Cruise and idle, pilot jet, effect of size on - " or "Pilot jet, effect of size on idle and cruise" same article.

diaphrams create a vacuum/pressure differential in relation to throttle opening which brings the slide up or down which has the needle inside. this is the part that makes it a constant velocity carb.

I see from your pic u have cobras, if u have a K&N airfilter also and with the ethanol gas u most likely are leaned out at WOT.

[Old Geezer Richard]

  Thanks CA , yes sir along with the Cobra pipes I am using a K&N filter with out the pre-filter .....  I'm kinda wondering if I might have a small pin hole leak in ONE of those diaphrams ????? or MAYBE the jets need to be cleaned or just replaced because last summer CA , after having neck surgery from some Jackass hitting from behind in his pickup truck he blessed me with four herniated discs and eventual neck fusing , any way my bike sat up during the whole summer with no riding , I would just go out in the garage and running her for about 10 minutes every other day .... I know that ain't the same as riding but thats all I could do at the time ... now I had wondered if Maybe the jets had developed some some build up from this crappy ethanol gas we have to use from sitting up .... didn't think about putting some Stabil,  just used Seafoam Duh ... I'm trying to get around yanking out the carb cluster and replacing the jets .... if I do , maybe I ought to go with the bigger jets to compensate for the Cobra pipes ???? Thanks for the info CA    Thanks the Geezer....