Fluctulating Idle Speeds/Poor Gas Mileage??!!

I did a quick search on this topic, hope this isn't a repost!

I bought a 87 VFR700 last summer off a kid who had pretty bad debt troubles for a really cheap price, and she runs like a champ. I put her away for winter while I was up at school - did the usual: Threw some Seafoam in the tank, ran it through, then topped her off with some Stabil, and ran her with the gas off to drain the carbs.

She started up great this spring, but I've been noticing more of a fluctuation at idle speeds. She'll sit at a somewhat constant idle, but if I blip the throttle, she won't return to the same speed, it'll even go over/under by sometimes as much as 400rpm. My fuel light comes on alot earlier as well not, yesterday it brightened up after only 150 miles! I used to be able to go almost 180 miles before she came on!

I'm guessing that it is a vacumn problem...?

Have any of you run into these problems??

 

Could be a possible vacuum problem, or clogged pilot jet that is making the carbs run out of balance. Spray some WD40 down near the carb boots to see if you have a vacuum leak. You'll have to pull the carbs off to check your jets and you'll probably want to check the floats and float height. If you are still having problems after that you might have to synchronize the carbs.

 

What would I look for after spraying the WD-40?
I would think WD-40 would cause the engine to run rough if it gets into the intake system.

 

You spray the stuff near your intake boots to see if there is a vacuum leak there, if there is your RPM will change. If not, no leak down there.
Do it with the tank and airbox still on of course.

 

I too have the fluctuating idle problem... If i'm sittin' at a light, it'll be idlin fine and then jump up on me... *sigh* seems I may need to go over carbs again...

 

I figured it was something like that, wasn't sure of the flashpoint of carb cleaner.

Try running some Seafoam in a tank first, that will help clear some gunk.

 

the carb cleaner will make the idle pick up if there is a leak.... check your vac hoses and make sure they are all connected and not cracked...aflter all it is a 23 year old bike and 99% sure that they are the original hoses.....

 

Try synching the carbs, and be sure the throttle cables have some slack.

 

With my old CB750 i had a similar problem. Check for cracked vacuum hoses and make sure the tank vent hose is not clogged or crimped. You'd be surprised how much can be fixed by checking that tank vent hose!

 

I would guess a vacuum problem as well, the seafoam (or more likely age) could have brittled up one of your vac lines. inspect each one at a time... look for poor seal, plugs or cracks.