stumble at 4000rpm

[Slamfire]

So ive been though the carbs. Dissasembled cleaned, set floats. I have not synced them yet.The bike works great.

Except cruising down the highway. I can ride at 4000 rpm for 10 minutes or so no problem. After that if I Give it a little throttle she stubbles then pulls. if I wack it to wot it takes off fine.


It may just be me but it seems to act up in the mornings and also if its foggy. on the way home from work in the evening its fine? So im kind of thinking a coil problem, but when I wash it, it still runs fine...

Im just wonding if maybe its alittle rich? At this rpm is it the mains or pilot?


thanks Matt

 

[06VMAXIMUS]

Believe the needles start pulling out of the mains at 4K. I'd sync them before doing anything else though.

 

[donnelly317]

more use full information would be are you running stock set up or stage 1 or stage 7 kit?

 

[Slamfire]

stock carbs, new spark plugs, stock air filter, cobra slipons . Idles great. On the sync note, isn't that notly noiced at idea and slight rpms?

 

[Slamfire]

idle screws set to 2 1/5

 

[davidon]

From an old carb guru's email (TC Campbell)

Cruise at 4k in 5th gear..hold RPM steady (count to 5) and then whack it WOT as quickly as you can...we don't want to feel the slightest delay or hesitation (if we do we have the needles set too rich). This does not work at 3.5 or 4.5k..only at 4k

 

[Slamfire]

I have moved the needle one notch ( Canadian bike) and now the tips are starting to go white. I don't really dare to go further?

 

[06VMAXIMUS]

stock carbs, new spark plugs, stock air filter, cobra slipons . Idles great. On the sync note, isn't that notly noiced at idea and slight rpms?

Not sure to be honest, but if its idling good they must be close:ummm:. You sure you have the little o-ring's in place on the slide covers?

 

[donnelly317]

Sync typically idle and low rpm. U didnt loose little oring in the cover? Did you really check diaphragm make sure no holes or tears? If its turning white I'd go back down with needle

Sent from my SCH-I535 using Tapatalk

 

[rebel318]

nope I know forsure the orings are still there.It worked great tonight but not this morning...

 

[06VMAXIMUS]

Try giving a little choke when it stumbles and see if it gets better or worse

 

[thor_eyerdhal]

With the Cobra slip ons, you should decrease the size of main jets...
Try 147.5 ones..

 

[jagco1]

Could be a jet not size right for the exhaust or carbs need cleaning.