mileage... a whopping 10 mpg!! and ideas?

I hoping you will be able to help, i've been messing around with my xj700 for about a year now. I've went through the carbs multiple times, ive replaced the plugs multiple times, and other this' and thats'.

my bike runs great, it idles ok, the major problems are that it only gets about 10mpg, and that at take off it "cuts out" or "bogs down" until about for a second or two, and then seems to run great, or great for how it has ran since i've owned it.

I the plugs foul out as fast as i put them in, and the mixture seems or is really rich, i mean in the garage or i guess the neighborhood stinks bad Shocked .

I'm going to take the carbs off again and take the mixture screws out and see if all that stuff is there. I guess my main questions were if you got terrible mileage before you found that you were missing pieces, and also any other ideas, i still haven't messed with the floats, another thing i'm going to do with the carbs off.

Hopefully this reaches you, i really wanna ride my bike. Thanks for any advice, Scott

 

-Valves in spec?

-Float levels set using fuel and the "clear tube method?"

-What method are you using to vacuum sync?

You're "dumping" fuel at that rate; there's a reason for it.

 

Sounds like you went part way through the carbs multiple times. You are saying now that you are going to take out the mixture screws. That should have been done at the initial cleaning. Don't try to take short cuts. You have to completely clean all the orifices and ports. When you do part of the job, you will be in there time and time again. All settings must be correct. After completely disassembling and cleaning, bench syncing, clear tube method of float adjustment, then reinstall and vacuum sync but as Fitz says, start with the valve adjustment before trying to sync the carbs.

 

An XJ could get 5 MPG if all you do is tune in the garage and ride up the block. But if you went 30 miles on 3 gallons, then yeah, you win the prize for thirstiest XJ !!

 

LOL yeah about 30 miles a take for the last year, it's cheaper to put on the back of a truck and have someone drive me around. anyway...

Here's whats going on now, i took the cabs off again and went through the mixture screws.

Next thing i'm gonna do is check the floats using the clear-tube method.

Is there another thread that talks about checking the valves, or/and vacuum syncing.

Im no mechanic, but really good, well somewhat good at following directions. Do you guys think i should take it to a shop.

I must say, i do appreciate you guys, thanks a ton.

Scott

 

You should check the float levels with the bike running. Use the clear tube method and I bet your levels are way high.

 

Sorry, but that's wholly incorrect. Float levels are BEST checked and adjusted with the rack off the bike and mounted in some sort of fixture so that it's level in all directions. By all means use the "clear tube method" but you don't do it (on or off the bike) when the engine is running.

Valve adjustment how to: http://xjbikes.com/Forums/viewtopic/t=14827.html and addendum: http://xjbikes.com/Forums/viewtopic/t=29209.html

I would rule out taking it to a shop. Most shops simply won't touch bikes this old; those that do often have no clue as to what they're doing and can quickly make matters worse (or just lighten your wallet.)

 

thats what i kinda figured about a shop, plus what fun is that??

Checked out that valve adjustment link, that is awesome, great job on that, makes someone like me feel pretty confident about undertaking the task.

I planned on rigging something up to feed fuel into my carbs while there on the bench, so i can get them right without putting them on and taking them off 20 times, oh the joys.

thanks guys, i'll let you know how its going, cuz i'm sure i'll have tons of new questions.