Quarter throtle stumble

when I clicked on new topic I had the feeling it was a lie, but I searched and couldn't find an answer. Went through the carbs of my seca 650{hitachis} cleaned color tuned synced. Changed out the 110 main for a 112 due to the use of a K&N filter. Idels great at 1000 or so puls very well at any thing above about quarter throtle. Fromjust off idle to just over quarter throtle it burbles like a two stroke with a foweled plug. Heavy load lite load coming down from above quarter hard on the gas light on the gas. It dosnot seam to care how. When it is at that throtle seting it burbles misses. Tryed switching out the spark plugs just incase, nothing. Float levels check out. HELP!!!!!!!!!!!

 

I am having an identical problem with my XJ750 Maxim. Found its from a very lean condition. Prob. caused by my 4 into 1 Jardine exhaust. Still with stock jets. I am going to try shimming the needle up one position and see if it helps.

Try riding in that condition and open up the enrichener, if it is a lean issue it will go away or improve.

 

Read the Plugs.
If it looks like you can afford to Enrich the Mixtures some ... do it.

Remember, when you are close to where the Engine is running really well all you have to do is move the Pilot Mixture Screws a couple of degrees to change the Aiir~Fuel Ratio.

It's a FINE adjustment. In some cases it's not more than a nudge to add a bit more enrichment to a Cylinder that is not optimum, but close to being so.

Spread the Tweak over a few sessions rather than doing it hit and miss.
Move the Mixture Screw in the appropriate direction for what you are dialing-in.

Usually, its OUT to rectify a Lean condition.
A degree or two and some road testing is the best method.
You get to feel-it if your Tweak was enough or not.