1982 XJ 650 Maxim rough running.... Help!

Hello!

I am new to riding in general, and managed to pick up an xj650 maxim a few weeks ago for a couple hundred bucks. It was in decent shape, a fixer upper, and I've fixed several things on it so far, but I can't get it to idle smoothly without dying.

So far, all the work I've done to it (not a whole lot, but still), is;
Replaced the spark plugs
Replaced the starter button (it was held on by tape.. Go figure)
Replaced the oil filter with an oil change
I have an air filter on the way in the mail to replace that
Replaced the throttle cable

I only run 93 octane in it.

Yesterday, when I was taking it for a spin (a mile up the road and back maybe 2 or 3 times, it was COLD out lol), everything was fine. After letting it sit for a few hours, upon going to start it, it didn't want to start at ALL. Running it on choke and prime got it to go and it idled around 4k RPM, and after taking it off of choke and prime it idled at what it usually does, around 1000, but then would slowly peter out. Giving it some gas wouldn't help it either, it just... Poof.

I'm thinking it needs some help with the petcock and carbs because it does have a slight misfire when it's cold and idling it high gives it a minor backfire, and considering who I got it from, I wouldn't be surprised...

Am I stepping in the right direction?

I just made this account to post for help, since I've gotten all of my information from this website so far and it helps me so tremendously. Anything is appreciated greatly.

 

Are the valves in spec?

This is the first thing to check before any carb work should be done.

 

I honestly have no idea.. I'm such a rookie with this kind of thing. How would that be checked?

 

not necessary, regular works fine

your bike has a vacuum fuel valve that lets gas flow when vacuum from the engine opens it, prime setting defeats this and gas flows all the time. it has uses but leave it on "on" normally

these bikes are cold blooded, yesterday you would have to had ridden it 2 or 3 miles before the choke could be taken off, you have to ease it off
test for the petcock, engine off, lever "on" pull fuel line off the petcock, should get no gas dripping, lever "prime" gas all over the place, be careful

 

Welcome to the group , agree valve clearance should be checked. Sounds like you have a vacuum leak and good chance you need to take your carbs to the church of clean . Leaks at the butterfly seals is a good possibility also have probably never been replaced. Go to xj4ever st to of the page chacal sells the seals and read the overload hour . Unless you already have one you should invest in a manual to help you in maintaining your bike. Cheers

 

Thank you everyone for all of your help. I have downloaded a copy of the Haynes manual so I consult that PDF every time I need help, lol. I was thinking the same thing with a leak somewhere...
The carbs are something I can't do personally, so will have to take it to get done.
How is the valve clearance checked?

 

Bigfitz's AIRHEAD VALVE ADJUSTMENT with Pics - parts I & II

 

we have a few members who can do the carbs for you,

 

Thank you everyone for all of your help. The more the merrier, I am very thankful I found this website!