bike won't stay running

[cabeenaz]

Hi,
I can not get my bike to stay running. when I give it gas it will rev up but then quickly drop back down n stutter like its about to die and will die if I don't let go of the throttle. this problem just happened today. what could be the cause of this? If more info is needed i will be happy to provide what i can.

[Skippii]

Originally Posted by cabeenaz

Hi,
I can not get my bike to stay running. when I give it gas it will rev up but then quickly drop back down n stutter like its about to die and will die if I don't let go of the throttle. this problem just happened today. what could be the cause of this? If more info is needed i will be happy to provide what i can.

Okay, let's see.

You didn't say if you are using the choke or anything, so I'll just start from the very basics.

To start you bike, put the choke on full, then start. It should start, and then rev up high. Let it rev the first 30 seconds.
As the bike starts to warm up (after 30 seconds), reduce the amount of choke to keep it idling between 4,000 and 5,000 rpm. In this weather (about 30*F for me) the bike really takes a surprising amount of time to warm up--2 or 3 minutes just isn't enough time, and it will want to die pulling away from stops. Let it completely warm up..might take 5 minutes.

After 5 minutes, turn off the choke and go for a ride. After you have been riding for a few miles, and you are sure your bike has completely warmed up, you can set the idle level--this is the knob under the gas tank, beneath the carbs. Set it so that the bike idles around 1,800 rpm. A lot of people don't have this set right, because they set it before the bike is completely warmed up--it really does take a few miles of running before it's up to temp.

Try this, and report back to us.

Oh, one other thing:

[the bike] will die if I don't let go of the throttle.

This doesn't make sense to me, so I just ignored it...the bike revs when you give it throttle, but will die if you let go? So it stays running if you remove your hands?

[flynjay]

Originally Posted by cabeenaz

Hi,
I can not get my bike to stay running. when I give it gas it will rev up but then quickly drop back down n stutter like its about to die and will die if I don't let go of the throttle. this problem just happened today. what could be the cause of this? If more info is needed i will be happy to provide what i can.

It sounds like your float bowls are filled when you first start, but are not be replenished fast enough when you give it throttle.

So I would assume a fuel delivery problem. Check any fuel filters you have. If you don't have any filters (you should) then maybe the fuel intake passage is blocked.

Also - Check the fuel petcock vacuum port maybe it is not opening all the way.

[cabeenaz]

i know to use the choke to start the bike and how to set the idle didn't think to put that part in. the bike is warmed up when I'm giving it throttle. as for the part you didn't understand, when i twist the throttle it will rev up then bog down tell it is about to die. if i keep the throttle twisted it will die, if i release it while soon enough when it bogs down the engine will stay running at idle. as far as the second post i don't have any fuel filters i know shame on me i just haven't gotten around to installing any yet. the rest of what you said i am not sure how to check any of that.

[choneofakind]

OP, 1st off, welcome to the forum.
2nd, we need a little background on the bike;

1 maintenance history
2 intake/exhaust/jetting setup
3 have you made any changes to the bike before it started giving you issues
4 how long have you had the bike for/ do you know what's been done to it?

anyhow, start with the basics. Check to make sure that your petcock is on the correct setting and is working. Check to make sure that it is not clogged where it gets fuel from the tank.

if that doesn't work, take the carbs off and clean the carbs. make sure you get the jets and all the idle circuits and check that the floats are set at the correct height.

for the record this site is really great for lots of help troubleshooting pre-gen bikes.

[flynjay]

Originally Posted by cabeenaz

i know to use the choke to start the bike and how to set the idle didn't think to put that part in. the bike is warmed up when I'm giving it throttle. as for the part you didn't understand, when i twist the throttle it will rev up then bog down tell it is about to die. if i keep the throttle twisted it will die, if i release it while soon enough when it bogs down the engine will stay running at idle. as far as the second post i don't have any fuel filters i know shame on me i just haven't gotten around to installing any yet. the rest of what you said i am not sure how to check any of that.

There are two hoses attached to the fuel tank petcock. One is the fuel outlet (larger) the other is the vacuum line (smaller diameter).

First check - normal engine produced vacuum is opening the petcock valve:

Turn the petcock valve to OFF.
Remove the hose from the fuel port (larger), some gas will come out so be prepared to catch it with a glass jar.
Turn the petcock valve to ON or RES.
Thumb the starter for 5s or so, be ready to catch the gas coming out of the tank. Fuel should come out of the tank in pulses.

Second check - Vacuum diaphram is intact and working properly:

Turn the Petcock to OFF.
Pull the vacuum line of the petcock and attach a hose to the vacuum input (smaller).
Manually apply vacuum to the hose (suck on it equivalent to drinking water through a straw). Too much vacuum could damage the diaphram. You should only be able to suck for a little bit and feel resistance.
If you don't feel any resistance STOP. The petcock diaphram needs to be replaced.
If you do feel resistance, continue.
Turn the Petcock to ON or RES.
Apply vacuum again, this time be ready to catch the fuel that comes out of the other port. Fuel should flow at a pretty good pace.

If either one of those doesn't flow gas well then you need to clean or rebuild the petcock. Also, there are fuel filters inside the tank attached to the inlet tubes (on my bike at least) so those could be clogged as well.

[cabeenaz]

I've had the bike for a little over 6 months. the oil has been changed every 1500 miles since I've gotten it. bike now has a little over 6000 miles on it got it with 2800 miles. every thing is stock as well as i am aware but i am at least the third owner. was running fine other then a dead battery but that was in the height of summer here in az. she was running fine in tell yesterday then this problem started. as for the website you suggested i cant seem to get it to work. flynjay i will go out n try that here in a min and report back to you guys. and thank you all for the help so far.

[flynjay]

Another possible cause is the main jet in the carbs is clogged. This is the jet that controls fuel flow in the upper throttle ranges.

Pull the carbs and clean them out.

I would still do the petcock tests. as you will be pulling the lines when you pull the carbs anyway.

[whatitstrue]

Just wondering is the choke closed when your doing this? if so you may be flooding it.(more fuel than air). I wouldnt aply throttle till the choke is opened up more as the bike warms up.

[whatitstrue]

Originally Posted by flynjay

There are two hoses attached to the fuel tank petcock. One is the fuel outlet (larger) the other is the vacuum line (smaller diameter).

First check - normal engine produced vacuum is opening the petcock valve:

Turn the petcock valve to OFF.
Remove the hose from the fuel port (larger), some gas will come out so be prepared to catch it with a glass jar.
Turn the petcock valve to ON or RES.
Thumb the starter for 5s or so, be ready to catch the gas coming out of the tank. Fuel should come out of the tank in pulses.

Second check - Vacuum diaphram is intact and working properly:

Turn the Petcock to OFF.
Pull the vacuum line of the petcock and attach a hose to the vacuum input (smaller).
Manually apply vacuum to the hose (suck on it equivalent to drinking water through a straw). Too much vacuum could damage the diaphram. You should only be able to suck for a little bit and feel resistance.
If you don't feel any resistance STOP. The petcock diaphram needs to be replaced.
If you do feel resistance, continue.
Turn the Petcock to ON or RES.
Apply vacuum again, this time be ready to catch the fuel that comes out of the other port. Fuel should flow at a pretty good pace.

If either one of those doesn't flow gas well then you need to clean or rebuild the petcock. Also, there are fuel filters inside the tank attached to the inlet tubes (on my bike at least) so those could be clogged as well.

If the bike has been riden recently and starts back up after it stalls I doubt it s a fuel delivery problem. Sounds more like its not properly warmed or inproper fuel/air ratio?

[cabeenaz]

they both seem to flow pretty good and bout the same. how hard are the crabs to clean? can i do it myself i wouldn't call myself mechanically inclined but i can change the oil and that kind of stuff. as for the choke no its not on when i apply the throttle.

[whatitstrue]

Originally Posted by cabeenaz

Hi, when I give it gas it will rev up but then quickly drop back down n stutter like its about to die and will die if I don't let go of the throttle.

If this is the case it sounds like too much fuel not enough air "FLOODING"
Thats why when you realeses the gas its ok.
I would sugest a little longer warm up and less choke before applying throttle and once you do apply thrtlle little bits till the bike warms up. Before you go tearing stuff apart.

Possibly dirty air cleaner but thats a streach.

[cabeenaz]

no matter how long i let it warm up it still does this. last night i let it warm up for a good 15 min and it still would bog down when i applied the throttle.

[whatitstrue]

when was the last time you rode it, before this happened?

[cabeenaz]

Tuesday to and from work

[flynjay]

Originally Posted by cabeenaz

they both seem to flow pretty good and bout the same. how hard are the crabs to clean? can i do it myself i wouldn't call myself mechanically inclined but i can change the oil and that kind of stuff. as for the choke no its not on when i apply the throttle.

The hardest part of the whole process is removing and reinstalling. I'd recommend looking at the Ninja250.org wiki page for intake
http://faq.ninja250.org/wiki/Intake

[flynjay]

Originally Posted by cabeenaz

no matter how long i let it warm up it still does this. last night i let it warm up for a good 15 min and it still would bog down when i applied the throttle.

If you ease the throttle up can you get it past the point where it bogs?

[flynjay]

Originally Posted by cabeenaz

no matter how long i let it warm up it still does this. last night i let it warm up for a good 15 min and it still would bog down when i applied the throttle.

If you leave the choke on a little bit, does it help or hurt?

[whatitstrue]

If you rode it that recently, with no problems I doubt its a dirty carb. It was raining tuesday, did you notice any problems then? Do you keep your air cleaner good and oiled?

Also will it hold revs above 2- 3,000 with the choke aplied? And what weight oil are you using?

[cabeenaz]

it seemed fine when i was riding and now that i think bout it it did something similar to this. it only happened in the morning so i always just assumed it was the cold. if i apllie the choke n give it throttle it does the same thing except drop back down to were the choke has the revs at n kinda bounces around a bit. im running 10/40 for the oil as for the air filter i was getting ready to do that today on my day off then this happened. i dont know bout the oiled air filter i was goin to look up how to do it. i can not for the life of me get ninja250.org to work on my comp but i can on my phone grr.

[whatitstrue]

So if you leave the choke on some it will hold? If thats the case just leave the choke on enough to where it will ride then get a couple miles on the bike and push it in. In the colder weather I usually have the choke applied some for the first few miles. Thats not unusual

[cabeenaz]

no it wont hold the revs just wont die on me is all. still bogs way back down. just looked into the airbox i really wish i had done this a long time ago as there apears to be no airfilter in the box. and now i just feel really dumb.

[flynjay]

Originally Posted by cabeenaz

i can not for the life of me get ninja250.org to work on my comp but i can on my phone grr.

Have you tried a different web browser? Firefox, Chrome, Safari, etc...

[flynjay]

Originally Posted by cabeenaz

no it wont hold the revs just wont die on me is all. still bogs way back down. just looked into the airbox i really wish i had done this a long time ago as there apears to be no airfilter in the box. and now i just feel really dumb.

Did you remove the snorkle an just see the two plastic frames with no foam filter?

No air filter would make it run lean. Colder air is more dense than warm air. So maybe you just went past the too lean to run mark.

You definately need an air filter. It is just a piece of foam (right shape and density) that is coated in oil.

[whatitstrue]

Well if its warmed up and dies or bogs way down to almost stalling when you apply throtle with the choke bothe opened and closed. Then theres really only one place left and thats the carb. You can start with emptying the float bowles and see if there is any water in there..And give the carbs a cleaning could maybe help. possiblely check your spark plugs also (for fouling)? And clean and oil your air filter.

[whatitstrue]

Originally Posted by cabeenaz

no it wont hold the revs just wont die on me is all. still bogs way back down. just looked into the airbox i really wish i had done this a long time ago as there apears to be no airfilter in the box. and now i just feel really dumb.

If theres no air filter deffinetly pull/drain your float bowles and check for water if you were riding in the rain the other day. That means there was nothing to stop the rain from comming into your intake.

[cabeenaz]

thank you all for the help everything i can do now will have to wait for my girlfriend to get home so i can go get parts.

[flynjay]

Originally Posted by whatitstrue

If theres no air filter deffinetly pull your float bowles and check for water if you were riding in the rain. That means there was nothing to stop the rain from comming into your intake.

The stock intake has a pretty tortous path for water to get into the intake boots, but it is possible. You would see water puddled in the intake box.

Draining the carbs is never a bad idea though. It should give you an idea of how dirty the carbs are.

Note that after draining the float bowls, the bike will take a little longer to start as you have to refill the bowls.

You can get around this somewhat by applying manual vacuum to the petcock valve to get fuel to flow and refill the bowls.

[whatitstrue]

Originally Posted by flynjay

Did you remove the snorkle an just see the two plastic frames with no foam filter?

No air filter would make it run lean. Colder air is more dense than warm air. So maybe you just went past the too lean to run mark.

You definately need an air filter. It is just a piece of foam (right shape and density) that is coated in oil.

No filter would cause a leaner condition but if that was the problem I would think choking the carb of air would have cured that.

A filter is most definetly a must though

[whatitstrue]

Originally Posted by cabeenaz

thank you all for the help everything i can do now will have to wait for my girlfriend to get home so i can go get parts.

Good Luck, let us know how it goes!!!!!!

[flynjay]

Originally Posted by whatitstrue

No filter would cause a leaner condition but if that was the problem I would think choking the carb of air would have cured that.

A filter is most definetly a must though

I was thinking along the same lines, but I don't know if the choke is effective through the whole throttle range.

Carb cleaning is definately in order, espically with no air filter.

[flynjay]

Originally Posted by cabeenaz

thank you all for the help everything i can do now will have to wait for my girlfriend to get home so i can go get parts.

If you do end up doing the carb cleaning. It is worth it to do the battery box mod.
It makes it sooooooo much easier to get the carbs on and off.

Down side is getting the airbox out of the bike. Easiest way is to remove the rear wheel and internal fenders.

[cabeenaz]

what is the battery box mod? and i will definitely let you guys know how it goes n now that i see some kool local guys Im think i might keep the ninja and just get a second bike instead of replacing this one.

[flynjay]

Originally Posted by cabeenaz

what is the battery box mod? and i will definitely let you guys know how it goes n now that i see some kool local guys Im think i might keep the ninja and just get a second bike instead of replacing this one.

Basically just cut the battery box off the airbox, making sure not to puncture the airbox. You then reinstall both pieces.

When you go to remove the carbs, you remove the battery and box which allows you to slide the airbox farther back making getting at the carbs easier. The ninja250.org wiki has a description.

[cabeenaz]

well got an air filter on it and drained out the gas put a little bit of new gas in and seems to run great now so heres hopin. thanks again everyone for the help

[whatitstrue]

Originally Posted by whatitstrue

No filter would cause a leaner condition but if that was the problem I would think choking the carb of air would have cured that.

A filter is most definetly a must though

Originally Posted by flynjay

I was thinking along the same lines, but I don't know if the choke is effective through the whole throttle range. Carb cleaning is definately in order, espically with no air filter.

The choke should cover all throtle positions as it restricts air (chokes) to the carb. As apposed to an enricher that is its own "circuit" which adds fuel.

+1 on cleaning the carb when you get a chance. Safer than sorry with no filter in Az.

[whatitstrue]

Originally Posted by cabeenaz

well got an air filter on it and drained out the gas put a little bit of new gas in and seems to run great now so heres hopin. thanks again everyone for the help

Good to hear!!!!!!
Glad your running again.





+1 on that battery box mod.

[cabeenaz]

ya shes running really good now and Im going to clean the carbs probably round xmas. i work tomorrow and only get one day off tell xmas. Im thinking i may do the air box mod as well

[flynjay]

Originally Posted by whatitstrue

The choke should cover all throtle positions as it restricts air (chokes) to the carb. As apposed to an enricher that is its own "circuit" which adds fuel.

+1 on cleaning the carb when you get a chance. Safer than sorry with no filter in Az.

I thought the "choke" on the ninja's was an enriching circut and not a traditional butterfly choke.

If I'm not mistaken it opens up a needle on the exit side of the carb which would make it effective at all throttle ranges.

[whatitstrue]

Originally Posted by flynjay

I thought the "choke" on the ninja's was an enriching circut and not a traditional butterfly choke.

If I'm not mistaken it opens up a needle on the exit side of the carb which would make it effective at all throttle ranges.

You are correct, I had to go look. It is an enricher.