Fuel economy

I finally was honored with a free bike. This happens to be a 93 vfr750 11000 miles. Needed a carb. clean and synch new plugs and hydraulics touched up. Not bad. Its bone stock with no aftermarket parts and stock jets and needle height. The rear plug indicate a lean mixture and she likes getting choked even on hot days. The problem is after riding through two tanks of 93 gas Im only getting 100 miles of in town commuting before the fuel light comes on. I could probably push it to 120. This kinda sucks I was excited about having touring bike not a bar cruiser. Any thoughts. Tires are okay chain has some stiff links sprockets fine. Have not checked compression or valves.I apologize if this was covered. I only saw newer bikes in the search for cures.

:xxx::bootyshake2:

 

The bike has a totally analog fuel "measurement" system save the low fuel light. Stop by any paint store and get a stir stick to measure fuel level. 100 miles on a full tank means something is haywire.

For service IMO you are best off staying oot of the local Honda shops. Same deal.. They will have some dude that is not as old as the bike working on it.. If they even smell "valves" your free bike will not be free for long. A really skilled mechanic can "hear" if the valves need attention.

My two-bits says, check your tires again or have them checked. If the bike needed the carbs hosed oot, no telling how long the rubber has been on your bike. Again, same deal avoid the dearlerships.

 

Thanks Billy

I avoid dealers like chinese tires. They probably wouldnt touch it anyhow.My bike is older then 5 years. I work for an independent shop so cost is no object thankfully. I think I m going to load up a gallon of gas and ride her till she poops out and see. Tires are spec psi. I think Ill go through the carbs again if the compression check and valves look good. Thanks for the help boss

 

that bike will hold 5 gal. fill up ans see how much you put in, this will tell the accurcy of fuel gauge

 

Why are you filling up with 93? These bikes are happy on 87, you're not pouring in extra power just wasted $$

 

Hard habit to break. I used to own a k bike :crazy:

 

As a wild-assed southern-boy i would say the carbs need cleaning since you indicated that choke is needed even when hot.

This tells my haid that the pilot circuit is not working correctly.

As you know, the pilot jets are the smallest and hardest to clean and verify opening diameter, plus the emulsion holes, plus the mixture screw port thru which it idles.

It the pilot circuit is no-op due to the mixture port clogged, then the throttle plates had to be screwed open wider than intended with the idle speed adjust screw in order to keep the fuker running at idle. The throttle should be totally closed at idle, but if gapped open will expose the transfer ports under the throttle plate and this pulls a huge amount of fuel at very inefficient airflow rates thru the venturi.

Did you happen to pull the mixture screws when cleaning?

 

Having dealt with the now tits up U-Honda and spoiled rotten having as "my guys" in the form of George Dean and Mick Vallantine and a couple of other BMW fanatics. I think the culprit will be found.

A short version of one I read aboot in Cycle World mag..

Dude does a frame up on an older Harley. Rides the bike to the Spring Farklefest in Daytona. May have been even a Knucklehead.. Aboot the same time the "World's Largest" HD outfit opens in Daytona. Dude needs an oil change and this 5 story HD boutique service dept. doesn't know how to do it. The procedure is terribly complex and requires technical expertise in things like opening up the filler cap and removing the drain plug. Oh! and having something to catch the oil in. They probably had an official bar and shield drain pan for that.

 

Yep I pulled everything include the o rings and washers on the air fuel. I wouldnt be shocked if It ate something or I missed something. The rock ape that owned it before hand was a piece of work. Thanks for the help.

 

the fuel light on my 93 comes on at about 120 miles. Filling up right then, it'll take 3.5 gallons, so I figure I've got 1.5 to go once the light comes on.
Total range would be about 170 miles.

That's about 34 mpg, not much better than my Civic, but I'm pretty she's running pretty rich (based on smell).

 

Its a official. I ran it till, pop fart blahhhhh. It was a disappointing 132 miles. Im going to clean and adjust the carbs again then valve and compression check. Thanks folks for the input.