Hey all I'm working on a friend's bike 2000 cbr600f4.. bike starts idles good revs in neutral good but when I'm driving it once it hits 7000rpm it cuts out until it gets to 9500rpm then it takes off really good. Things I have done so far new spark plugs, tested coils new fuel filter,cleaned carbs ,checked gastank vent line,tested fuel pump got 300ml in 5 seconds.. tested charging system at idle 12.5v reved up 13.8v ... anyone have any ideas what to check next thanks in advance

 

Welcome to the forum Darren, off hand can't think of anything other than Carbs coming onto the main jets, how well were they cleaned?

 

I took out jets needles and needle valve put carb cleaned through everything and blew out with air. The carbs were spotless when I took them apart

 

There are lots of internal passages that should also be cleaned, not just the jets. They do have a reputation for being very difficult to clean thoroughly.
However could not be anything to do with your issue. One of the other will be along shortly with other ideas that may help.

 

I blew put all passages when I cleaned everything as well

 

Air does nothing for secret hidden passages in carb-body. There are tight 90-degree bends that hangs onto clogs. Air will just pack clogs tighter into each other. Dried petrol turns to plastic that can't be dissolved with pretty much anything and needs to be mechanically scrubbed out. Also all bleed holes in carb-venturi, jets, emulsion tubes need to be poked out with matching gauge soft copper wire. You'l find they'll push out little plastic plugs of dried petrol like little grains of sand.









I've done this on at least 100 sets of carbs that were stumbling just like yours. Same story every time with exact same solution.

Here's scrub-brushes:
And use PEA-based fuel-system cleaner:

- Red Line SI-1
- Techron Concentrate Plus
- 3M Max Strength Fuel System Cleaner #08814
- Royal Purple Max Atomizer 18000
- Gumout All-in-One (might be off list soon due to lowering amounts of PEA)