Carb problem

[Guy]

I purchased an XJ in Nov with 15K, need lots of tlc.
When I cleaned the front caliper it ran well. With it I got new carb manifolds. When the weather got cold I decided to clean it up and put on the manifolds. I have removed and polished all aluminum, crank covers too, except the shocks and fork tubes. Just cleaned on the bike. Have done the Nyalic thing to all. Checked out second gear while down, looks good. Changed all fluids except fork oil. Had to replace the tach as well. Cleaned outside of carbs, removed bowls one at a time, very little residue in bottom, blew out with carb cleaner and replaced. Discovered that air intake nozzle was out of air box inside and allowing air to bypass filter. Filter was probably original. Dumped the gas, did not look good. Now all back together and flood out the air box. Pulled carbs ( a little silicon sprayed on the boots helps) and found #4 float hanging. Carbs back on and no leaks. Fired up, warmed a few minutes, Idle is a little rough and will not rev well, sounds like slight popping out the right exhaust almost like slight backfire. Well out on the road, a little rough at start, but open the throttle and good by. So I have a low speed circuit problem?Where should I look?

[TopCatGr58]

Hey there Guy,

A little spray of carb cleaner will not do the trick. The Idle circuitl is full of small holes and passages and are easily gummed up with the varnish from old gas sitting in there. You will really need to pull the carbs, turn them upside down and pull the jets, both main and idle, and give them and the circuits a good going thru. BTW, the XJ carbs idle set screws, commonly called the pilot screws are near the top front outside edge of the carbs where they slide into the intake boots. You may see four round brass plugs in the holes across the bank of 4 carbs, which will mean that they have not been pulled, and therefore the Idle circuit can't get truly cleaned without removing them. They are pressed in, you can take a small drill bit and drill thru them, they are only about 1/8" thick so you have to go slowly and gently to drill thru them without damaging the adjusting screw head below. Then I used a sheet metal screw, screwed it into the cap, and then put a pair of lockjaw pliers on it, and then used a small hammer to tap against the pliers to pull/pop the caps out!! Once out, you can then remove the set screws and then ensure the idle circuit path is clean, then replace them and set them to 1 1/4 turns out from a GENTLE seat, the tips are very fragile and can get broken very easily!

Do a search on carbs, check the tech tips, you'll find lots of info regarding cleaning/synchronizing, tuning the carbs! Good Luck.
T.C.

[mitch]

Guy

Guy , I would start with a complete dissasembly of the carbs, how to do this is in the maintence and repair sections, make sure you push out the emulsifaction tubes as well . Then when they are clean bench sync the carbs again that info is posted on the above sites. Did you run it with the dirty filter out if so it might be leaning out , You need to have the filter in, just a thought HTH good luck and enjoy your XJ they are a great bike..............MITCH

[Guy]

Thanks for the quick reply. I understand the need for cleaning, however the bike was running well when I removed the carbs. They were not varnished, really clean, just more of slight discolored. They sat about a month before I got them back on.
I guess I will pull them again ( not one of Yamahas better ideas).

Guy

[mitch]

Dirt

Dirt tends to get dislodged when you take the off and move them around . Once your here a while you will notice almost everybody ends up cleaning thier carbs 3 times or more LOL. Hence the term triple clean,Been around old bikes all my life never could afford new ! Trust me these guys know what they are doing . Welcome to the site and good luck on the XJ.........MITCH

[John]

Instrument Cluster

Guy, how does the new cluster work? Good I hope. This is the John in Texas who sold it to you. The odometer is showing 12k miles on it , right?
Looks like Mitch and TC gave you some good advice on the carbs. Read all you can on the topic, and take your time. It's not riding season yet any way. You should be to do it. If you have the carbs out, remove the main jets, and push the tubes that the mains screw into (emulsion tubes) out from the bowl upwards to the air horn, or throttle body. You'll need to have the slides removed to do this. Check and clean all of the little holes in the tubes. They affect the throttle from idle to about 1/3 throttle, Then the main jet needles take over.
Good luck, and don't be afraid to ask any questions. Remember, the only stupid question is the one that you DON'T ask.

[Guy]

Hey John I just sent an e-mail direct. Tach works well, as I said I removed the tach mechanism and replaced the one in my cluster, which had a better face.
Well, I pulled the carbs a third time and checked the pilot jets. one may have has a slight something in it. I had about 100 precision drills given to me late last year. I found one that just fit in the jet and just lightly passed it through each jet. Using a length of clear 1/4 inch tubing I blew through everything I could find. I did not drill out the adjusting screw covers on top of the carbs. When reinstalled the bike idled smooth, reved and runs well.

Thanks
Guy