XJ650 carbs are a PITA

[XS1100 Newbie]

Been trying to set the floats on my XJ650. I have reset them 6 times now. I have been setting them at 17.5 MM as the book calls for. Measuring from the gasket surface (less gasket) to the top of the float, at the opposite end from the needle and seat. I have tried tilting the carbs so the tang contact is very light on the needle and setting. I cannot get the fuel level up high enough when i put fuel in the bowls. I have the tank set up above the carbs, so i can put fuel in the carbs like the bike. I have also tiped the carbs a little instead of being level, and still the level is not high enough. I am going to try setting the floats at a level that will give me a good wet setting, and then see where i end up. I have never had this much problem with carbs, on autos anyhow. Any suggestions from you folks that do this blindfolded? LOL

[Yahman]

Setting the floats dry only gets you close. If everything is in new condition then it will get you a little closer. The most accurate way to set the floats is always by the actual level of fuel in the bowl. I set mine on the bench with everything level and fuel in the bowls. I use a small gas tank hanging above the carbs. When they are all at the same and appropriate level, and they stay that way without changing, then I put them on the bike.

I find that if I measure them after they are all at the same fuel level, that the floats are all set differently.

Larry

[XS1100 Newbie]

Thanks Larry. I will set each one independently wet. A little bit of a hassle draining the gas each time, but if it works, it works.
Bob

[yozzie]

just wondering if you have a hard cold starting problem with your 650. I've got an '82 650 and it never got enough gas when cold starting. Once warm, it started great. I took the carbs apart and cleaned them multiple times and could get gas shooting out the choke tube in the bowls. But just never enough to start the bike. I read about other people with these bikes having the same problem and just resorting to shooting starter fluid through the air box.
I ended up drilling the choke tubes in the bowl a tiny bit larger. Now the bike gets lots of gas at start up.

[SFerinTEXAS]

are you useing sight gage tubing to see the actual fuel level?

[XS1100 Newbie]

Just got them all set finally. Yes i was using a clear tube. Had some trouble with number 4, but finally got it. I have not had this thing that long, but it definately starts hard. From what i have read, they all do. They don't have a choke, just an enrichment valve. I am thinking about trying to start it with it in the PRI position, and give the throttle a pump. First i better see if it will even run after working on the carbs.

[XS1100 Newbie]

I finally got around to reinstalling the carbs after surgery on my hand. The bike starts great, but it does not want to come off idle. I have to leave the choke (enritchment) on full to get much response. It also will idle high that way. Seems like it may not be getting enough fuel. I will see what the clear tude says while running. This is pretty much the same problem i had to begin with, only worse. I am in the process of trying to get the plugs out for the air/fuel screws.

[XS1100 Newbie]

Well, i got the plugs out, and done some adjusting. What a difference it made. I have not synched yet, but i bet that will help also. I suppose i need to readjust, and synch again to get it real close. Part of my problem was also a fuel filter that was to small, and cutting off the supply.

[wingnut]

Newbie the Hitachi's are a PIA that's for sure. The XJs are one of the most cold blooded machines I have messed with. I have to run mine with the enricher open until the motor is really warm or the throttle response is for s#$T. One thing I found was that the induction system, the air filter and air box are the choke points for this engine. Any air leaks between the front of the air filter and the cylinder head will cause you grief. They run the best on the verge of self destructive lean. I fought with mine for weeks before I got them right. The seal surface on the air cleaner must even be good or it will run lean. The best improvement I made was taking the mains and the pilot jets up one size. The US bikes use one size and the rest of the world use the next size up. You lose about 1 MPG but the engine runs cooler and more responsive. Guy over on the XJ web site will sell you all 8 jets for about $30 for new. You have the float levels right so it would just be a matter of changing the jets, readjust the idle mixture screws and sync. I had mine on and off so many times I was thinking of Velcro if you get my drift.

[XS1100 Newbie]

After adjusting the air fuel mix, which helped tremendously, i synched the carbs, and wow what a difference. This little bike pulls really good. Absolutely no problems with cold starting, and the plugs are looking really good. I feel good about this job. Now i don't worry so much about taking on my XS1100.
This 650 is a fun little scoot, but i would not take it on a long trip. Compared to my XS1100, it feels like i am on a mini bike, on a bumpy road with flat tires.

[wingnut]

Glad you got it running right. They are really fun in the twister's. They pull as well as the 1100 up to about 80, after that its see ya later. After riding the 1100 thru the curves and then jumping on the 650 its like you just think about going into the corner and its done. They are about 200 lbs lighter. I haven't tried going further than about 150 miles on mine at one time but then why would I with the SH sitting there waiting to take me where ever I want to go

[Geezer]

The enrichener circuit does the same thing as a choke. Anyway the hard starting problem is probably because the tiny passages in the float bowls that feed the pick up tubes are plugged. I've seen this hundreds of times and it's not a hard fix...

Geezer

[daveyg]

My '82 XJ 650 was picked up with 18K miles, and ran fairly good when I got it, I did an oil change and then sync'd the carbs and put in a UNI air filter, and the difference was like night and day, that little bastard pulls hard from 0-100 with no problem at all. My buddy gets all pissed cuz he can't keep up on his '05 Ninja 650. But after almost 6K miles last year, it feels like it needs sync'd again and the air filter cleaned. But I can't compare it to the 11, cuz well... I got it for $25 cuz it hadn't ran in decades and I haven't gotten it together yet lol.