Im at a loss right now. ive been through EVERYTHING on this bike.
Problem started last summer

Work done last fall
carbs clean, rebuilt, sync'd.
Jetting as follows: (Bike is stock minus Jardine RT-One Slip on)
Pilots all 40
Needles all 3rd up
Mains 138/140/140/138
tank cleaned
new fuel filter
new fuel lines
new air filter
new coils
new spark plugs
Problem was completely resolved for about 3 weeks
then it came back


Idles fine
No problem reving in neutral all the way to the limiter
Go for a ride is its fine to about 6k then flutters to 7k, straightens out after that
It gets a second wind and takes off like a bat out of hell to redline.
Let off and its has no power back down to about 5k then comes back. Starts first turn of the starter EVERY TIME.
ideas? suggestions? I have an idea in my head but dont want to influence suggestions

 

Bottom line, carbs aren't OEM factory clean. And/or not configured to factory specs.

Carb-restoration required to take everything apart down to every last nut, bolt and individual components. Scrub out hidden/secret passages in carb-body with scrub-brushes and PEA-based fuel-system cleaner. Ultrasonic soak everything and micro soda-blast before re-assembling. Replace ALL rubbers: float-valves, float-bowl seals, fuel-rail O-rings, and even slide-diaphragms if needed. Set float-levels with wet-test to confirm. Sync carbs. If any of above was left-out, it would certainly cause running issues you're having.

Also ALL factory components needed: all jet sizes, all needles, all filtres and airbox. Common mid-range issue I've found is aftermarket needles from jet kits. They often don't match engine's configuration and its transition in mid-range. Fought exact same problem you had for years until one day I decided to completely disassemble carb and check to make sure each and every part was OEM factory. Turned out someone had replaced needles with some aftermarket parts and different mid-range transition caused super-rich spot in mid-range which caused stumbling.

Bike ran perfectly fine when leaving showroom floor. Will do so again when everything is restored to OEM factory condition.

 

im open ears to this but this wouldnt explain it running like a top for 3 weeks

 

Ok, something degraded in 3-week's time.

How was it running before those 3-weeks?
And for how long was it running like that?
What changed on bike recently?
Any kind of maintenance? Parts replaced?

 

it was running exactly as it is now. Pulled it off the road for maintenance immediately. all the work listed above was done, and it rode fine for 3 weeks then reaquired the exact same issue

 

I agree with dannoxyz on the break down of the carbs. I also go farther and remove the butterflies and run the carbs through a hot sonic bath. Helps with cleaning all the passages in the carb.
Did you make sure that none of the jets between the carbs didn’t mix? They are different between 1/4 and 2/3.
As for the stutter at 4K to 6k rpm, check to make sure carb bands for the insulators have not loosened up. Check to make sure air supply hoses are properly fitted. If these are all snug and fitted, pull the plugs and check the condition. This will let you know the carbs are tuned properly and not running lean or fat. Check the plug gap while you have the plugs out. If that checks out, check coil wires for visible damage and then check the resistance. If good there, check the peak voltage and resistance of pulse generator. If that checks, check the peak voltage and resistance of the coils.

 

updating as idig
plugs all look good and are gapped to .35 (ngkR cr9eh)
coils on the other hand....
the 2/3 coil is reading 8.6 primary/ 14.79k secondary
the 1/4 coil is reading 6.0 primary/ 0.95k secondary

i guess ill take a decent coil suggestion

 

Post updates as i tear the carbs apart again

 

Remember last "cleaning" only lasted 3-weeks. You gotta take completely down to every last piece possible. If it can be separated further, do it.



Spray "carb cleaner" no longer works due to removal of chlorinated compounds. So you gotta scrub out all hidden passages in carb-body with brushes and PEA fuel-system cleaner. It's the crap in these passages you didn't clean out last time. And the moved over time and clogged your jets and bleed-holes in carb-venturi. Gotta do complete job back to OEM factory-fresh clean. Otherwise it'll get clogged up in short time again.












Completely disassemble emulsion-tube and pilot jet. Poke out all lateral bleed holes with soft copper wire. Dried petrol turns to plastic and cannot be dissolved again. Must be mechanically scrubbed away. Also poke out all bleed-holes in carb-venturi towards float-bowl. Especially the mixture-screw hole.



Ultrasonic soak everything for days (except rubber parts). Micro soda-blast to clear out all grit and chads loosened by scrubbing and soaking.

Bike ran perfectly fine when leaving showroom floor. It will again when carbs are restored to factory-fresh clean with all factory settings.

 

thanks for the pics. They are completely broken down and the bodys went out to the local carb guru to be soaked in the ultra sonic cleaner. No shortcuts this time. cleaned before they went and will be cleaned again before reassembly. I updated the original post to show current jetting as well. Considering it just has a Jardine RT-One slip on exhaust does current jetting sound reasonable?
250' above sea level, pretty much riding between 50-90*