82 XJ 550 Stutters on acceleration after 65mph

Was running fine last summer.
Over the winter, I installed new intake manifold rubbers and gave the carbs an overhaul.

Upon putting her all back together, I installed a fuel filter that I got from our beloved Len.

NOW, at low speeds I have all the get up and go that I would ever need.
She idols fine, even when hot
Rode her to work today and tried to pass a 18wheeler.
I opened her up and she stuttered and took her time gaining any speed.

Possible reasons I thought of:
* Lack of proper fuel flow from the new fuel filter?

* float levels out of wack? (even tho I didnt adjust them, just cleaned
carbs and put all back together)

Stupidly I didnt remove the petcock... guess that filter could be all gummed up also...

I look forward to ideas from this awesome bunch of XJ enthusiasts


Dave

 

Float levels need to be verified using fuel and the "clear tube method" the 550s are FINICKY about float level.

After cleaning did you Bench Sync?

What method did you use to vacuum sync?

Where did you set the idle mixture screws to begin with, and what adjustment procedure did you use for those?

ARE THE VALVES IN SPEC? When were they last done? If the valves aren't in spec, you won't get a decent vacuum sync.

The valve clearances need to be attended to BEFORE any carb tuning; or you won't get far.