i just got my 92' f2 started, but the idle is extremely high (no tach, so i dont know the exact rpm). here's the story:

after sitting for over a year without running, i finally got the extra cash i needed to fix her up. took off the carbs and noted rust dust sitting in the bowls. also, replaced the float needles since the carbs began furiously leaking last year. to clear the rust up i put a gallon of phosphoric acid in the tank and let it sit in a few different positions for a couple hours. dumped it and rinsed it with gas. also, my overflow hose has a hole somewhere in the tank causing about a gallon of gas to leak out, so i plugged the end with epoxy putty, allowing me to fill the tank up to prevent further rusting. sprayed the carbs and jets with carb cleaner and took the d-shaped idle mixture screws out to be cleaned. after spraying starter fluid in the carbs and sucking on the vacuum hose to get fuel running into the empty carbs, she started up. battery doesn't hold a charge anymore so i jumped it with my car. however, the idle was really really high.

i thought it might be the mixture screws so i adjusted them to factory setting (2 1/8 turns out), but the problem persists. there is a little bit of play on the throttle; i noticed i can push it even further shut, causing the idle to come down slightly. when i let go and let the throttle sit, the idle picks right up again. when i open the throttle, the bike's rpms soar but dont fall for a few seconds after letting go. the idle screw isn't engaged at all.

maybe the answer is obvious and its simply running way too lean because of poorly adjusted mixture screws, or the throttle can be adjusted on the carbs and i don't know how, theres an alternative way to set the idle that i overlooked, or maybe i didn't rinse the tank out well enough and the gas is bad, causing the lean-esque feel. what do you guys think? thanks.

 

1. Never jump bike with a car...running. Try push start.

2. Hearing the detail, sounds like the throttle cable/ throttle sensor adjustment is off, something mechanically not right.

3. Try lubricating the throttle cable.


Ern may be able to give better suggestion.

 

First thing I'd check is the throttle cable/linkage and adjustment/lubing, as mentioned
by estate. Get that operating smoothly without hanging up. Regardless of whether it's
the issue or not, it needs to be addressed. Check the choke for the same-type issues.
I recently heard of one of the screw/bushings for the choke-plate falling out and causing
it to bind on one carb, so that it was never off choke. So eliminate all of that easy
stuff and get it behind you.

If you've done any adjustment to the mains, you'll need to go for the whole carb sync
and then idle adjustment, to get the carbs right. If you can't afford the guages, RPM
meter and right-angle adjuster, check your local tool rentals. If you plan on doing all
of your own maintenance, though, they will pay for themselves, quickly. That and a
factory manual.

On a side note, you mentioned, you had to block the vent hole on the tank.
The first warm day, you're going to flood the engine...all of the way through
to the exhaust.

I had a blocked vent-line on my F3. Got a warm day and while parked,
the heated fuel expanded through the lines untill it ran out on the ground,
at the mid-pipe. (Yeah, I had an exhaust leak, as well.)

If you can't fix the leak and un-block the vent-pipe, you're probably going to have to
replace the tank. I hate to give bad news, maybe someone will have some other
ideas on that front. Just wanted you to know the possibilities.

Hope this gets you headed in the right direction, Ern

 

i checked the throttle/choke cables and they're in working condition.

the tank has two extra hoses coming from it: one is a vent and one is an overflow hose - i plugged the overflow hose (the hole you see when you open your gas tank) which shouldnt cause venting problems.

the carbs were sync'd before i began endless maintenance, and i havent touched those adjustments at all. but would out-of-sync carbs cause the idle to skyrocket? what about the mixture screws?

 

nah, but a broke *** choke cable would

 

As mentioned earlier, if you do any work to the carbs, you should re-visit the vacume sync and then re-do the idle adjust, if you want the bike to run properly.

But first, assure proper operation of all of the sub-systems to the carbs.

Ern

 

i figured i'd take it all apart and put it back together again, just in case i missed something. re-cleaned the carbs, was very careful reconnecting the choke and throttle cables, looked for any cracks in the hoses, made sure the air filter was clean and the screws were tight. started the bike up, and it idled perfectly (and the idle screw does what it's supposed to do, unlike before). so that problem is fixed. HOWEVER...

now i'm experiencing a different problem. right after i started the engine, i gave it some throttle and it worked flawlessly. but once it warmed up for 10 minutes or so, any time i tried to give it throttle it died. i'm still wondering if the gas in the tank is bad... but what other things should i focus my attention on to troubleshoot the problem?

 

This maybe silly? But did you take off your fuel filter and try blowing thru it? Is the color of filter dark brown....clog?

Many may overlook this, but a clog fuel filter, will idle fine but once you throttle, flow is disrupted (starving gas) engine die out....

Or Air flow? Make sure no vacuum hose are disconnecting, bent, pinch?

 

In addition: don't know if you have this on your bike, there is also a part call a throttle sensor, if not properly install, will cause symptom like yours ....die out when throttle

 

now it won't start at all; I took the tank off and poured fuel directly into the hose with a funnel to bypass the vacuum to make sure that the vacuum wasn't the problem AND the fuel in the tank wasn't bad, but to no avail. it sounds like it wants to start (a little rumbling in the engine) and occasionally there was a slight cough coming from the muffler (but not a backfire). I lubed the choke and throttle lines and they work correctly. And I replaced the battery, in case my previous problem was caused because there wasn't enough power for the fuel pump to do its job(?) (according to a different forum post from someone experiencing a similar problem).