'82 XJ650 Engine feels lumpy 1,300 to 3,000 rpm

1982 XJ650 Seca 12,000 miles, no mods, overall good condition.
Just bought the bike last Friday and Im loving it but have a question when pulling away from idle at 1,300 rpm to 3,000 rpm the motor feels lumpy,not smooth and has mild coughing effect. After 3,000 it pulls very clearnly, any suggestions on curing this?
As an older biker I ride most often in the 1,300 rpm to 4,000 rpm range on local journeys.
Ive attached a picture of the bike.

 

You need to get the valves in spec and service the carbs. And run it over 6K with some regularity; the powerband pretty much STARTS at 6K.

 

Welcome simon! I won't help you with the question, since I don't consider myself one of the experts here. But add your bike details in your signature so anyone can quickly see what you need help on, and in my signature you will find the list of what to do to any old XJ that isn't mint.

 

Fitz advice is pretty much par for the course for a new-to-you bike. You'll solve a lot of carb gremlins with valves in spec and freshly cleaned carbs.

Also, bring your tires, and brakes up to snuff, and consider fluid changes and a new battery if you don't know it's already been done. It's been repeated many times, but rubber brake lines, master cylinder seals have a service life of 4 years, caliper seals have 2 years, and only brake pads, shoes, and tires can crumble/delaminate with age. While there is a safety margin built into those numbers, 30 years is way past it.

Also check steering head, swing arm, and wheel bearings, as well as fork seals, and the output of your charging system.

Though it sounds to me like your carb problem is related to the pilot circuit, so pay special attention to it when cleaning your carbs.

You'll likely notice that there's barely any torque below 3000 rpm, and peak torque is around 6000. The "power band" doesn't start until you hit peak torque, so when you fully tune your bike, get used to running it up there. You'll need to be closer to your power band if you need to sprint out of trouble (i.e. a situation where accelerating past danger is safer than stopping). If you're just putting along, you don't need the extra torque, but if you need to move, dropping a gear or two to put the engine in it's power band is required.

Also, you pic didn't attach.