XT600 Carb Secondary Issues
 

Working on the rehab of my 2nd '86 XT600 (should have never let the first one go). After doing all the major service, it now runs great except for one major problem. It starts well, idles well, has good throttle response, and pulls hard at lower RPMs. As the RPMs climb, it suddenly and repeatedly dies and then immediately pulls hard again. It is violent... pull hard, nose dive, pull hard, nose dive, pull hard, nose dive, etc... just that fast.
It's as if when the secondary slide opens it just dies and then when it drops again it takes off.

I thoroughly cleaned the carb (including ultrasonic), cleared all passages, new rubber and o-rings where required, set float height, set sync screw, etc. I'd like to think I'm pretty proficient with moto carbs so I'm pretty sure everything is OK, but obviously it's not.
I pulled the secondary jet to make sure it was clear and fuel was getting to it.
What in the world am I missing?

What rpm does it die at ? 3500-4000 ? consistently ? no matter how slow or hard your accelerating ? Or will it go higher/lower depending how the throttle is manipulated ?

might be way off line here but is the diaphragm ok?...

Thanks for the replies.
This carb has a piston, not a diaphragm.
Cuts out around 4-5K rpm (tach doesn't work).
I can't say how it acts at part throttle. I was only doing full throttle pulls.

Fuel cut, check filters first.

yes, there is plenty of fuel flow to the carb.

Ok, had same problem when filter inside carb had some rust around, only cut at high rpm. Cleaned carb and extra filter before carb and problem solved, this is many years ago and never had any problem like this,