idles great but dies when I accelerate. acceleration problem [Archive] - Kawasaki Vulcan Forum : Vulcan Forums

: idles great but dies when I accelerate. acceleration problem


marcmjc
07-10-2011, 11:56 PM
First forgive me if this problem has been answered b4, I am hoping that since it is July 2011 that there are some new solutions to my problem. I have a 2007 Vulcan 500LTD which sat for about 12 months. I replaced the battery, cleaned and re-oiled the air filter, changed the spark plug, added sea foam with new gas to tank,(but did not completely drain the tank). The bike idles great, from full choke to half then to closed, but when I engage the throttle the bike dies. The bike will slightly run in first gear with the choke in half position, and sometimes the bike will accelerate fast and stick there then come back down, sorta freaky. The bike dies with choke in completely if I try to accelerate. I am now stuck. Is this a vacuum problem? I see some varies suggestions yet none that really sticks. Any new solutions to what seems to be a problem alot of us have?

pacomutt
07-11-2011, 02:17 AM
First forgive me if this problem has been answered b4, I am hoping that since it is July 2011 that there are some new solutions to my problem. I have a 2007 Vulcan 500LTD which sat for about 12 months. I replaced the battery, cleaned and re-oiled the air filter, changed the spark plug, added sea foam with new gas to tank,(but did not completely drain the tank). The bike idles great, from full choke to half then to closed, but when I engage the throttle the bike dies. The bike will slightly run in first gear with the choke in half position, and sometimes the bike will accelerate fast and stick there then come back down, sorta freaky. The bike dies with choke in completely if I try to accelerate. I am now stuck. Is this a vacuum problem? I see some varies suggestions yet none that really sticks. Any new solutions to what seems to be a problem alot of us have?

You could clean the gunk off of the main jets, which conveniently sit in all the crud at the very bottom of your carburetors. That means removing the carb bowls and maybe the carbs themselves to do it right.

Blaine
07-11-2011, 06:52 AM
You could clean the gunk off of the main jets, which conveniently sit in all the crud at the very bottom of your carburetors. That means removing the carb bowls and maybe the carbs themselves to do it right.
Ditto: Sounds like the pilot jets are plugged also.Sometimes it takes a couple of days for the Sea Foam to work.You can add about twice the amount of Sea Foam if needed.Also should be filled with fresh gas.The old dead gas won't burn properly,no matter how much Sea Foam is added.
:):cool:

marcmjc
07-12-2011, 12:57 PM
now after cleaning all the vents for the gas cap, rechecking the ground on the battery (still no throttle acceleration) I am going to completely empty the tank, clean her out and get her ready for some total fresh petrol, and c where we end up then off to the carbs and jets. thx for the replies, very much appreciate the time.

here is a mechanic 101 question, why does the bike idle so dang smooth either full choke, half, or closed choke, but the acceleration is unobtainable and the bike dies? why does the idle not keep the bike running even if I pull the throttle?

Pete7874
07-12-2011, 01:32 PM
here is a mechanic 101 question, why does the bike idle so dang smooth either full choke, half, or closed choke, but the acceleration is unobtainable and the bike dies? why does the idle not keep the bike running even if I pull the throttle?
Maybe someone can correct me if I'm wrong, but the engine needs a specific mixture of fuel and air to run. Your partially clogged carbs/jets prevent this proper fuel-air ratio from occuring which results in a stall.

At idle, the holes in the jets are big enough to provide the little fuel that is needed, so the fuel-air ratio is good enough for the engine to keep running. Now, the result of you rolling on the throttle is that the engine is supposed to be given more air as well as more fuel. Well, it is probably given more air at that point, but it's not given more fuel because the jets are partially clogged and the fuel can't flow any faster. So there is a mismatch in air-to-fuel ratio and the engine dies.

pacomutt
07-12-2011, 01:38 PM
now after cleaning all the vents for the gas cap, rechecking the ground on the battery (still no throttle acceleration) I am going to completely empty the tank, clean her out and get her ready for some total fresh petrol, and c where we end up then off to the carbs and jets. thx for the replies, very much appreciate the time.

here is a mechanic 101 question, why does the bike idle so dang smooth either full choke, half, or closed choke, but the acceleration is unobtainable and the bike dies? why does the idle not keep the bike running even if I pull the throttle?

There are usually three jets, or metering systems in carburetors. It appears that your idle jets are clear, but remember that idling uses very little fuel. The pilot and main jets are the critical areas where the real flow is. When you open your throttle beyond idle, the air/fuel ratio changes to mostly air, starving the engine of the ratio it needs to run. Quit wasting your time and take care of the carburetors that sat neglected for a year!
Once you drop the bowls, you'll see the mess inside. Gummy gas, water, and the chemical reaction between the water and the various metal parts in the carbs create real havoc. Take the carbs off. Take them apart. Remove the jets. Clean them with carburetor cleaner and blow out with compressed air. Look through the jets with a strong magnifier to determine if the holes in the jets look clear and round. Don't try to run any drill bits, wires, etc. through the jets. The most I will do is to take one strand from finely stranded copper wire, and very gently try to clear a jet hole.
Get a manual and follow it for the reassembly and float adjustment.

Here's a product to remember at the end of this riding season: Sta-Bil

Pete7874
07-12-2011, 01:45 PM
Here's a product to remember at the end of this riding season: Sta-Bil
Yup. That's what I used last winter. And even with it, after 5 months of sitting, I observed similar effect to what the OP is describing, but not as drastic. The engine would choke and hesitate a bit, almost as if ready to stall when I gave it gas. However, after about 15 minutes of running and then a few miles of riding, it seemed to be back to normal. I ran some Yamaha RingFree in the next tank just to help clean things out.

pacomutt
07-12-2011, 01:56 PM
Yup. That's what I used last winter. And even with it, after 5 months of sitting, I observed similar effect to what the OP is describing, but not as drastic. The engine would choke and hesitate a bit, almost as if ready to stall when I gave it gas. However, after about 15 minutes of running and then a few miles of riding, it seemed to be back to normal. I ran some Yamaha RingFree in the next tank just to help clean things out.

Pete, you beat me to the last post. Yeah, gas today seems to turn to sewage after about thirty days. As soon as someone starts producing unleaded aircraft gas, which is required by law to keep its freshness, I'll start storing the bike with that in it- plus some Sta-Bil. Of course if you have a bike with no cat converters or oxygen sensors.....

Leaf
07-12-2011, 02:21 PM
If you have crap in your gas tank, clogging the petcock, that can also cause this sort of behavior, even when the carb is squeaky clean. Imo, drain it, check for rust/crap in the tank, run some new gas and seafoam, and proceed from there. :3

marcmjc
07-12-2011, 11:45 PM
whoa guys a big thanks this is the best forum yet you guys seriously rock. I havent messed with engines in a great while so I am rusty, so your help is a GREAT help!

thanks.