How best to check the jets

My pilot screws are less than one turn and I'm still a little rich. How is the best way to check and see if the jets have been drilled. They have the correct number and look good the the naked eye, but damn, the gas has to be coming from somewhere--and it's the same on all cylinders. 30mpq around town and 35 on the road at best.

 

Have you checked your float valves? Does your oil smell like gas by chance?

I just went through the same thing. Super rich. Wasn't the pilot screws, which were backed out a lot as well.... It was the float valves.

 

If you know a machinist who does precision work he could measure them. Most people don't have access to the tools so the best way to know is replace them.
You have more than pilot jets that will effect fuel mileage. Clean well tuned carbs, proper float level , functioning slides, proper main and pilot jets all have an effect on mileage.
Don't forget that valve adjustment.

 

I've clean and wet set the carbs several times, as well as getting the valves in spect. All the slides, floats, etc are clean and appear to work well. I have replaced the float valve seats and needles. When I bought he bike it had a uni filter, and I've replace it with the stock filter. That's why I've come to the conclusion that it must the the jets. If I can't find a machinist, I guess I'll just buy new ones.

 

My 700X had the pilot jets drilled out when I bought it. A tiny bit goes a long way. I pulled my hair out truing to get that thing tuned, with the screws closed it still was too rich. Since the jets said they were the right size I didn't think they were the problem. I have a s set of numbered drills that help when checking jet sizes. I don't remember if I figured it out by checking with the drills or if I replaced the Jets out fo frustration. Anyway replacing the jets fixed my problem.

 

Thanks. I have a set of carbs coming and I'm probably going to swap out the jets and try them before ordering new ones. I assume that you replaced the main jets, not the pilot jets--correct? Did it help with your fuel consumption? I'm getting only about 30 in town and 35 on the road and I'm easy on the throttle.

 

The handy dandy chart right here....

http://xjbikes.com/Forums/viewtopic/t=28026.html

BUT you are going to use the ass end of the drill bit to measure the size of the hole. dont use the pointy end! it's soft brass, you run the risk of scratching or cutting the jet which would ruin a potentially good jet....

 

WAIT, whoa--- "appear" to work well?

Have you WET-SET the float levels? Carbs off the bike, level, using fuel and clear tubing? Individually and accurately?

If a float or floats aren't working properly, or are for that matter, you would SEE it when wet-setting the floats.

If you already have, then OK, proceed with replacing jets. If not, go back and do it, and correctly.

 

Damn Fitz... remind me to watch what i say around you...

 

Oh, yes, I've wet set them several times. When I had them out I even floated the floats to make sure they all floated at the same level.

 

OK, cool. There's a big difference between "seem to work well" and "wet-verified." I thought you had, but the wording left it open to question.

Carry on with the jets.

 

Tabaka45,
It was the pilot jets that were drilled out. I am currently running 107.5 main jets. It starts easily and warms up quick but is hard on gas. I have bought some 105's, which is the stock size, but haven't gotten around to installing them. I'm currently getting about 45MPG.

 

Thanks for the info. I would think I had died and gone to heaven if I was getting 45mpg.

 

I'd love to get 45mpg.

I doubt I could have a Jockey take-off on my 750Max and get close to 45.

What do your Plugs say about being so stingy on the Go-juice?

 

Plugs are still rich, even with the pilot screws open less than one turn. I can almost close the screw and still have the blue flame. Since I've done everything else several times, I'm considering the jets as a last measure. Barely getting 35 mpg at 60 mph just seems low.

 

"Still Blue" with the Pilot Mix Screws almost closed means you are too dependent upon the Main Fuel Jets.

Bench Sync to make the Throttles close.
3X5 Card Strips tight.

Adjust the Mix Screws to make the Plant IDLE without the Throttles open.
Get Blue that way.

Then, add some additional Richness to overcome any hesitation at the instant you go Off-Idle.

When you arrive at this point, ... you'll be very close to having Fine-tuned the Plant.
"Tweaks" away.

Tweak = about the width of a Dime.
NOT at 1/4 Turn or 1/2 Turn.

Make it IDLE right, ... first.

 

My plugs show a little rich, maybe I'm not getting 45MPH I get about 80 miles to the tank so maybe my mileage is really 35 to 40.

 

I'm guessing you're talking about your XJ700N?

My XJ700XS MPG was in the upper 20's to a high of 34 and I had the carbs apart three times to make it as new. For me it was #3 & 4 cylinders that were the bugger with #4 the only one I couldn't resolve. A 2nd opinion and going over by exhondahack found the emulsion tube was worn on #4 which he replaced with a good one and new pilot jets were installed at the same time. Since those replacements my best MPG to date now is 49 MPG and I get around 43-45 MPG on the interstate if I stay steady around 65 MPH.

My 82 650 maxim with YICS eliminator can get up to 54 MPG if I ride like an old lady and I can't seem to get less than 47 no matter what I do. The carbs on that bike work beautifully.

My XJ1100 carbs have the Dynajet Stage 1 kit installed and the bike gets around 34 if I don't treat it hard, 29 if I get aggressive with the throttle. It also has the YICS eliminator installed. I'm currently putting new jets in a spare carb set and have stripped them down to metal and carb dipped them for several days & now in the process of reassembly. I'm curious to see what difference in "drivability" and MPG there is between the two carbs. Bottom line - I really appreciate the acceleration and throttle response with the carbs with this dynajet kit in it and hope not to lose much performance with stock carbs but I would like to see better MPG than a top of 34.