Only getting about 22 MPG?

[XSNate]

I have replace a lot of parts including buying new carbs. New coils and points charging pretty well. This bike is now running pretty darn good! But only getting about 22mpg? I heard of guys getting close to 50! What do you guys think? Is my motor just tired at an estimated 20k miles? Runs strong though?

 

[650Skull]

At 22mpg you will wash the bores and be up for a rebuild. Identify your carbs, (Pics are best), and check out the set up in them.


Your bike should have BS38's 2F0's

 

[Growl]

Is something rubbing? Like a tire against the frame or fender? Brakes dragging?

What color are the spark plugs?

Is your odometer wacked?

 

[XSNate]

For some reason my bike has bs34's. I'm running 45p and 142.5main 1 1/2 turns on mix screw.

My rear brake rotor may need a look at? It never felt good? Plugs are chocolate.

Odometer? Well I really don't trust many parts that are over 30 years old

 

[650Skull]

The 34's are good carbs. I'm not really a carb guy but the mains and pilot are to high, especially the mains.

Original setting 132.5 mains and 42.5 pilots. your bike seems to be pretty much standard, ( No drag pipes or pods), so there should be no need to deviate from original settings.

I wouldn't do to much more running around till the carbs are set right.

Have you done a compression test?

 

[gggGary]

check the float valve o-rings. even if you are riding it like it's stolen it's hard to get much below 35mpg.

 

[grizld1]

Thought you wrote that you bought "new" carbs, Nate. Evidently you mean that you replaced your old carbs with better old carbs. Follow Skull's advice and return to original jetting. While you're replacing PJ's and MJ's, have a look at the pilot air jet in the back of the intake bell and be sure that's right as well--and no, I won't give you a number, click on "Tech" and click the link to the XS650 Garage Carb Guide. Also examine the needle jets and jet needles (and no, I'm not talking about the float valve seat and needle). They're the primary metering elements in the cruising range, and are often the cause of excessive fuel consumption when worn or damaged by aggressive cleaning.

 

[XSNate]

I bought a completely rebuilt carb with all new parts from old school carbs. The stock jetting was way too lean. I was not able to get good plug readings until I moved the pilot up one size. ( I practically had the mix screws almost all of the way out! Over 4 turns!) I now get a good chocolate color after a plug chop. ( I have lots of extra plugs now) the main might not have needed to be bumped up but since I had them open I feel it's better to be a bit rich and run the risk of fouling a plug rather than lean and fry a piston! It runs good through the rpm's.

I will get a compression test hopefully tomorrow.

 

[grizld1]

"Chocolate brown" insulators means the mix is right? Gee, the things ya learn on this board! It's obvious that you know more about reading plugs and tuning carbs than I do, so adios and good luck.

 

[XSNate]

Well I didn't think they were bad, and it runs good. No bogging no hesitation, snappy throttle. On this chart when it had stock jetting I had numbers 22-25. With the richer jetting I have numbers around 15. Do you not agree with this chart? If not do you have one you like better?

 

[650Skull]

Grizld and 5twins are pretty much the ones to listen to about carbs. their patience is almost as bad as mine, but remember these guys must get tired of people who don't read the Carb Guide and then question what they say.

Not a criticism just a fact.

Here is a link to the "Carb Guide" through the 'Tech Menu' here.

Read the Carb Guide, the holy grail to BS carbs, (no not short for Bull shit).

an extract from some posts from the next best person i would take advice from, xsjohn. (alas no longer with us, RIP), and you will find a pic here to help you.

 

[XSNate]

Oh I fully understand. That's why I didn't snap back. I do have experience with mikuni carbs on my Honda four wheeler that I used to race. I just have something weird going on here? I would be more worried about the jetting if it didn't run well but IT DOES! So I will have to investigate further???

Forgot to mention... At a stop I have an almost unbearable amount of fuel smell? I installed a new gas cap seal. That did not help.

 

[gggGary]

Have you smelled your oil? What taper, needle jets are in there?

What mufflers and air filters do you have?

An electronic ignition will usually improve fuel milage, but not double it....

 

[XSNate]

Stock exhaust ( some rust holes in the bottom) so they leak. I do have mikes pods on it until I get some uni pods.
Stock needle

 

[gggGary]

"mikes pods on it" That could do it right there. The real cheap mikes pods block ports on the carb bell.

 

[angus67]

did you say you were getting color after plug chop?
Its hard to get color on a plug these days because leaded gas is hard to find. that's what colors plugs quickly.
I understand you have experience with carbs on your racer, but I find it hard to believe your getting plug color on new plugs after a(one) plug chop.
most of the charts you find of plug colors are old, when leaded gas was still around.
I agree with leaning your carbs. get rid of those pods and get your unis.
http://www.motorcycle-superstore.co...ID=AvantLink|NA|55963_d3fe7c65&WT.MC_ID=54020
the above link is priced for two.

 

[650Skull]

If you don't re-jet and start again then a new thread in the future is going to be "why am i burning oil and my oil smells like fuell"

 

[XSNate]

Angus67, agreed about the chop. But when it's lean I can read white hot. I ditch those plugs then adjust.

 

[wherearewe]

What about a simple fuel leak? I mean if you can smell fuel when you stop, perhaps you have a petcock leak, split in fuel hose, bad tee joint between the carbs or some such.

 

[Brian902]

Just to be clear.

Here is what you get for mileage if you are getting 22 mpg compared to 50 mpg.

How much gas to you put in and what is the miles you traveled?

Miles/Gallons = MPG

55/2.5 = 22

Numbers rounded up so chart shows rounding.