PLEASE HELP- Low mpg!

I've been riding my xj 650 for a couple months now and this is my first motorcycle, but I think my bike is getting really crappy gas mileage. From what I've been able to gather my tank is about 4 gallons from completely empty. But when I ride I only get to 55 miles max before I have to switch to reserve. When i refuel at that point it takes 2.6 gallons. This is only 21 to 22 miles to the gallon. Because of my trouble I've had with running out of gas and being stuck on the side of the road I refuel when I switch to reserve. So my question is: Is this normal or do I have a problem here? I understand this is an old bike but I get about the same gas mileage in my suv, and I dont have to refuel as often. lol I want to use this bike as a commuter to college, but its about a 1 hr and 45 min drive and I cant make it on one tank and its the desert so gas stations are few out there. If anyone has any advice or knows of ways to fix this PLEASE help! I really want to start commuting on her!
Also, in the past few months I've cleaned and synced the carbs. Was having trouble with it running too rich and backfiring while riding, but I've adjusted my fuel mixture screws down to exactly one full turn out and seems to run smooth now.

 

22 mpg is low, my 1100 s get 38 mpg. I would think you should get in the 35 to 40 mpg range. Have there been any modifications done to the bike or is it stock? There are many things that effect fuel milage, tire pressure , riding habbits are a start. Look at your plugs and air filter, are the plugs black and filter dirty? Carb tuning is important also, do you know what size jets are installed?

 

Have you:

-checked and adjusted the valves?
-bench sync'ed the carbs?
-checked/confirmed or adjusted the float levels using a clear tube and fuel?
-done a running vacuum sync? (YICS blocked if applicable.)

I would strongly suspect float levels but the above need to all be done, and pretty much in order.

 

+1 on above advise,
Lay your plugs on brown cardboard,(1,2,3,4) and post-up a picture here.

 

if you have low compression you'll have lousy gas mileage. check your engine compression.

standard should be around 156. the bike originally got 60 miles back in its day.
todays fuel won't get you that though.

i had 140 compression and got 38 miles on my 81 xj650.

check your air filter box for any type of oil trace where the crankcase breather connects to the air filter box. that will indicate blowby from the engine.

check for fuel leaks. although you should probably smell something there.

my suzuki gets 42 miles. but when it sits for the week. miles go way down. the gas seems to be vaporizing. can't smell anything but every weekend i go riding. it always takes about 3 gallons to top her off. no matter how much gas she has sitting during the week. and she holds the same 3.4 gallons.

 

Ok I will be checking the plugs. But to answer a few questions I have bench synced the carbs, and done a running vac sync (yics blocked), and changed the oil, but could not get the damn filter off. Any advice to get that off. All I have to unscrew is this tiny little metal piece that I couldnt grip with anything. Also I've noticed some oil leaking down the engine mostly on the right side. Could that be a factor in this? Or what would cause that to happen in general?
Not really sure how to: check and adjust valves
check engine compression
check jet size
I've seen some articles on checking the float levels with the clear tube method. Any advice on how to do that Bigfitz52?
I'm low of $ right now, so anything too exstravagant or a trip to the shop is out of the question right now. I have limited tools as well.
Also, about checking the plugs, should i take them out, clean them, then ride for a certain amount of mileage, then check them? Because I was running very rich before and I would think this would make them sooty to begin with and wouldn't provide accurate results to go by what they look like right now.
Thank you for the advice and continued help

 

Having your pilots screws only one turn out is a sure sign that
way too much fuel is being used (at leased at idle to 1/8 throttle).
On most bikes that would cause such a lean condition that engine
damage could occure.

The filter should have a standard bolt in the center facing towards
the front of the bike. Unless it's been rounded off, a socket should
work just fine.
If rounded, a simple fix is to first try a vice grip and try to get
it to turn.
Or..flatten two sides with a file, grinding wheel (on a drill), or
whatever, down to a size that will fit a socket or wrench.
Contact Chacal for a replacement part as that bolt is the end of
the filters flow assembly.
As for running rich...that would be a cause for poor fuel economy
but 1/2 or less mpg is an indication several other factors are at play.
You will find all the info you need to do all the advice above on this
site. RickOMatic,Bigfitz, and many others have outstanding step-
by-step tutorials with all the details carefully covered.

Take the time to read all you can find on tuning your bike BEFORE
jumping in. The answer is here,but may have more then one cause.
So get to know HOW the fuel/combustion system works. Then the answer
will be found.
Good luck.

 

also, if the plug is rounded out. y ou can find a socket that will fit tight and beat it on with a hammer. that should get a bite enough to pull the bolt out. and it's long enough you can use your hand to wiggle it out of the socket.

basically it's making the socket bite into the bolt. i've used that method a lot back when i worked on cars. rounded lug nuts were all too common.

 

How Long does it take to do the valve shims?

 

Give yourself a couple of hours the first time; it's not a complicated process but it pays to take your time and be methodical: http://xjbikes.com/Forums/viewtopic/t=14827.html

It's usually a "two-step process" first step is to pull the cover, measure clearances and "read" any out-of-spec shims; then order new shims, gasket, donuts if applicable.

Second step is install the new shims, re-check all clearances, install new gasket, etc.

 

Quick Question: The legendary "Clear Tube Method"
Maybe I dont quite understand the entire process but is there a certain diameter tube I should use, and how do I measure the mm that comes out of it. Or do i simply get a clear tube, get one carb perfect, and then match all others to the amount of gas it fill in the tube?

 

Do a search; somebody just recently posted pics.

It's not a matter of what comes out of it; the method is outlined in both the factory and aftermarket service manuals.

It involves attaching a piece of clear tubing to the carb drain and opening it, and holding the tube up next to the side of the carb. The fuel level in the tube will indicate the fuel level in the carb bowl. The spec is very close, usually a 3mm range, and varies slightly bike-to-bike (Mikunis vs. Hitachis.)

Chacal (XJ4Ever) sells a metric-marked gauging tube that makes the measuring part easy. I put a piece of masking tape on the side of my carbs and mark that using a super-fine point drafting marker. (Overkill, admittedly.) Or you can use a piece of plain tubing and a metric ruler. (Remember the 3mm range.)

And yes, the easiest way is to get one right and then match dry. But you still need to check (and adjust if necessary) each one individually with fuel.

Tip: When adjusting: If you know you bent the tang, then you went too far. Think "nudge."

 

THANK YOU so much! I wanted to give this a shot, but didnt want to start without verifying first. Thanks Bigfitz i can always count on you for a prompt and accurate response.

 

Remember rack has to be level side to side and front to back. You can do it on the bike by propping it up; it's a lot easier with the rack off the bike and mounted in a jig (I use my 4 1/2" bench vise) completely level.

 

Remember rack has to be level side to side and front to back.<quote>

Level from side to side, yes, but you should try to have them slightly inclined from front to back, to simulate the 'on bike' possition.