fouling #4 plug

Hey guys, I'm new. I live in Arizona and picked up a 1982 xj650 as my first motorcycle a few months ago.

The bike had pretty clearly been sitting with somewhat less than a half hearted attempt at cleaning it up for sale and I paid accordingly. I fixed some electrical issues, rebuilt the petcock, and cleaned a very small amount of surface rust from the fuel tank through electrolysis. I inspected the brakes and changed the oil.

The bike runs rough. It idles rough and stumbles when you give it gas. If you're gentle with the throttle and patient it'll rev to about 4k rpm and it smooths out a lot and rides pretty happy above there. I pulled plug wires and determined I was only running on cylinders 1-3. All of the spark plugs were fouled so I replaced them to see what happened and the bike ran beautifully. It was fast, very eager to rev, it idled very smoothly. It did smoke from the right tail pipe. After the first ride plug 4 was fouled again and it ran poorly again.

I have purchased a motion pro valve shim tool but haven't checked clearances yet as I'm not clear on which valve cover gasket to order.

I am hesitant to tear into the carbs myself as I think they're smarter than I am and they greatly outnumber me. Local shops have given me really high "I don't want to work on that" estimates and I suppose they would double or more on a non-running bike I've inexpertly hacked into.

I guess I'm at a point where I'd like to get the engine running well for around $200 and maybe 8 hours of my time or move on. I'm not broke or afraid of getting my hands dirty and I could certainly maintain the bike as issues arise beyond that, but I really want to ride more than I want to tinker and test ride. Today was our first day of the year over 100 degrees and pretty soon you won't be able to swing a dead cat without hitting a young kid begging to ditch his modern reliable fuel injected bike for anything with doors and AC. After it cools off in October or November I suppose I could easily sell the XJ for what I have in it as a "been sitting - needs a tune up" special.

Any thoughts?

 

dont fear the carbs. take your time. read a walkthrough. feel accomplished when you defeat them.

 

I felt like you when I got my bike, and I've worked on cars for all my life. So I let a shop clean the carbs and it cost $225. Within a week it had fouled out the plugs and so I decided to give it a try. I read all the instructions on this forum and took my time and it really wasn't bad at all. The hardest part for me is getting the carbs back on the bike. I've done it 10 or 12 times now and it goes quickly. If you have any mechanical ability and experience it will easy if you follow the instructions. Take your time and be patient. And don't be surprised if you have to take them off several times before you get it right. I can't remember who said it, maybe Fitz, but if you can't work on these bikes yourself, it's going to be very expensive. One suggestion--take pictures as you dissemble and refer to them as you reassemble.

 

Brakes, valve clearances, carb cleaning, those are just the tip of the iceberg and will eat up your $200 budget and way more than your allotted 8 hours.

So if you stick with this bike there's definitely some tinkering in your future.

If it's a 650 Maxim with a YICS motor, you need the rubber gasket with the hold down donuts.

If it's a 650 Seca with a non-YICS motor, you need the fiber gasket and probably the rubber plugs.

 

Valves are in spec, I broke the rack, individually cleaned every tiny crevice in each of the four carbs to their original gleaming bare aluminum "Christmas morning 1982" luster (they honestly looked good already with no plugged passages and the carb cleaner left in the tub was barely tinted) and got everything back together, and got it to run pretty nice for about 7 miles, BAM, now 3&4 are both fouled.

On the plus side, Mrs. Rico agrees that $7,990 plus tax, title, license, and doc is a small price to pay for more family time and less garage time. I will take one for the team and graciously accept a zero mile 2014 FZ-09. You know, for the kids.

 

After mine were cleaned by the shop they also fouled a couple of the plugs and the others were black. I went back and cleaned the carbs myself, verified that the float levels were correct, the right size jets were installed in the right place, the slides really "clunked", and then re-synced the carbs. I used a colortune plug to get the pilot screws slightly in the blue and then through a series of very minute (thickness of a dime max) adjustments to the pilot screws finally got my plugs running clean. Before every adjustment I would clean the plugs and then I would run the bike for 50-75 miles over a few days in both city and highway driving. Not only are my plugs running clean but my fuel consumption went down. So, if you have everything cleaned, installed correctly, synced, and, of course, for Bigfitz--valves adjusted, I would concentrate on the pilot screws.

 

sometimes the enrichment circuit needles dont seat well (marring on the needle, or the fingers which pull up on them are in the wrong order), and leaks extra gas into the system. I had a helluva time figuring that one out.