Hanging Idle

[ak_907_ak]

Hello,

I can't seem to figure out the problem of my hanging idle. Most times it will go back to normal idle at 1500rpm, but sometimes it will stay at 1800 to 2100 and really slowly go back down to normal. It only does it when warmed up, from what i can tell, the warmer the engine, the worse it gets.

I've read other forums and people seem to think vacuum leak would be the biggest cause, followed by: out of sync carbs, float bowl level low, valves need adjusting, o-rings in carbs where the needle sits, needle diaphragm punctured.

I've tried adjusting mixture screw, and now I am at 1.8 turns, which seems pretty low.

[kkim]

what are your jetting specs? intake and exhaust mods?

[ak_907_ak]

snorkel removed, but airbox is still there, yoshi full exhaust
#100 main, factory pro needle, clip in the 3rd position
idle mix screw 1.8 turns out, the best i can tell (that milwaukee screw driver is not the accurate, it has some slack in it.)

This all started when i put on my exhaust and the re-jet, i completely took me carbs out, which leads me to vacuum leak or internal carb problem.

Bikes got 760 miles on it

[kkim]

sounds like your idle mixture is too lean. I used the alternate method in this lnk.
http://faq.ninja250.org/wiki/How_do_...dle_mixture%3F

[ak_907_ak]

all right, i will try that tomorrow, but when i first put on my exhaust, i had it set at 2.5, and when i blip the throttle it would go below idle and the raise again, but the idle would hang also...

i will try it anyway, see what happens, its easier that the alternative, which is to remove the carbs and carefully inspect everything

[kkim]

was the bike fully warmed up when you were setting the idle? I rode mine around for 10-15 minutes, came home, then worked on setting the idle.

[ak_907_ak]

well, what i did is since 2.5 was too rich i rode it around for an hour, went home and changed it to 2.0. Rode around another hour and still felt to rich as the throttle was still dropping below idle, so I set it to 1.8. not perfect though.

I also noticed that the choke would not work with 2.5 screws out. It would actually get so rich that it would kill the bike. Now at 1.8, I actually have to use the choke to start it in the morning, usually raises RPM by 400-700 than without choke.

[kkim]

Something doesn't sound right.

try adjusting the idle using the link and see what happens. If you can't make any progress, remove the carb tops and check the diaphragms for tears.

[CANTFUNCTION]

It sounds like you are to lean.

http://www.factorypro.com/tech_tunin...m_engines.html

Look at
4. Idle and low rpm cruise

[Buffalony]

I get a flat spot at 4000 in 1st, 5000 in 2nd and I think 6000 in 3rd. Theres is nothing. the bike revs higher but doesnt go any faster. Is that normal for all stock?

[ak_907_ak]

OK, I took my bike apart, looked at the diaphragm and they look fine, but i read in another threat that they should not be touched. How come?
Before i took it apart, I started it, and sprayed the pipe coming from the carb to the cylinder with starter fluid, and it suddenly picked up rpm, so maybe a vacuum leak.
Now i'm trying to put the bike back together, but i cant figure out about the 3 way split above the cylinder. One goes to the vacuum valve, and I'm not sure where the other 2 go.

[VeX]

That's the best way to find a vacuum leak. I had that similar problem with a supercharged vehicle and it took me forever to track down! Sure enough I had a couple of tees (one for the boost gauge, one for the blow off-valve, etc.) and the rubber hose around one of the tees started to crack and would leak intermitently. So spraying the ether on it didn't diagnose it then. It was finally me jiggling the hell out of the hoses and watching a vacuum gauge to find it. You got lucky

As for the vacuum ports, on the left cylinder (when sitting atop the bike) goes to the port in front of the carburetor, ties into the vacuum valve for the fuel, and if you still have the Klean air system the other side goes to that. Although I still have a 3 way tee there and have a check port for sync'ing the carburetors (maybe you put a test port there and forgot about it?)

[HKr1]

Originally Posted by ak_907_ak

sprayed the pipe coming from the carb to the cylinder with starter fluid, and it suddenly picked up rpm, so maybe a vacuum leak.

Originally Posted by VeX

That's the best way to find a vacuum leak.

Water bottle is kinda the best, it will take rpms down.

You have to be real careful spraying carb cleaner/starter fluid around. Even minutes after it looks like it has dried up..... It's still flammable. Dude in our shop almost burned an old chevy blazer to ground looking for a vacuum leak with that stuff

[randomwalk101]

Spray on hot running engine? What if it catch fire?
Posted via Mobile Device

[VeX]

Well you aren't spraying it ON the engine you're spraying it at the vacuum lines. That and being highly flameable in gasseous form, if you fog out an engine bay looking for vacuum leaks you are setting yourself up for disaster. I've always done quick burst (that's all it takes). Never tried water, but that's a good idea. Is the RPM drop as noticeable as the RPM raise that ether causes?

[Buffalony]

[ROADandTRACK]

If the bike sat for more than a couple weeks it is most likely dirty pilot jets.

Don't spray carb cleaner in the carbs EVER!!

Must remove carbs to clean.

[ak_907_ak]

Well, I went for a 140 mile test ride today, the longest trip I have taken on the 250.
I gotta say that stock seat is pretty uncomfortable, and the fuel gauge is pretty useless. It goes from 8/8 to 5/8 in the first 10 miles, and then stays at 5/8 for the next 40 miles.
Even though I didn't do much low rpm driving, as most of the way was 60-70mph, I didn't seem to get hanging idles, and the choke seems to work too.
My only problem is the idle is inconsistent. I've got it set at 1600, but sometimes it will go to 1800 and sometimes only to 1200 (I find 1300 is way to low for idle, 1500-1600 seems to be the best). The mixture idle screws are set at 2 turns out.
I've got a GPS program on my IPhone, I just put it in my pocket and it tracks my ride for me.

[Ken08Ninja]

Originally Posted by ak_907_ak

I've got a GPS program on my IPhone, I just put it in my pocket and it tracks my ride for me.

What program are you using on your IPhone for the tracking?

[ak_907_ak]

It's called Motion-X GPS. Costs 5 bucks. It will also tell you you speed, average speed and max speed, which way your heading and has a waypoint feature.

[ROADandTRACK]

I think your pilots are still dirty since the idle is going up and down.

[Banzai]

Originally Posted by ak_907_ak

I gotta say that stock seat is pretty uncomfortable, and the fuel gauge is pretty useless. It goes from 8/8 to 5/8 in the first 10 miles, and then stays at 5/8 for the next 40 miles.

I agree on the seat!


As for your fuel level gauge, its a CLASSIC indication of a bad fuel level sender. It's about a 1 hour fix to replace, start to finish, assuming your bike is in full trim. Take it back and have the shop you bought it from replace it, if you're still under warranty. Otherwise, get a confirmed good one off of ebay and do it yourself, all of the torque specs are in the service manual.

[Buffalony]

Originally Posted by Banzai

I agree on the seat!


As for your fuel level gauge, its a CLASSIC indication of a bad fuel level sender. It's about a 1 hour fix to replace, start to finish, assuming your bike is in full trim. Take it back and have the shop you bought it from replace it, if you're still under warranty. Otherwise, get a confirmed good one off of ebay and do it yourself, all of the torque specs are in the service manual.

Sorry to go off topic: So the fuel gauge can be fixed to work normally?

[ak_907_ak]

Originally Posted by Buffalony

Sorry to go off topic: So the fuel gauge can be fixed to work normally?

that was kinda funny, since everybody is complaining about that thing.
Though it has been like that since I've got it and it's only got 940 miles on it.
Is there a DIY maybe here or on some other forum so I can get a general idea of what is involved?

Originally Posted by ROADandTRACK

I think your pilots are still dirty since the idle is going up and down.

I changed my pilots jets with the ones that came with the Factory Pro #1 jet kit. I believe the pilots are size 40, but I'm not sure. Are you saying there is stuff stuck in the actual jet, and if so, what would be a good way of cleaning them? I'm getting pretty good at tearing my bike apart, I can have the carbs out in less than 40 minutes.

[VeX]

A good solution would be to A) get an inline fuel filter and
B) If you don't put a ton of miles on the bike, run carb cleaner (the stuff you pour in your tank) periodically. The stuff is meant to treat 15 or so gallons, so with a 4.8 or so gallon tank you can run 1/3 of a bottle every couple of fill-ups.

The 10% ethanol in fuel wreaks hell on the little pilot jets and main jets of these carbs so a little preventative maintenance is king IMO.

[kkim]

check the clamps that hold the carbs to the cylinder head on the rubber manifold thingy. if they are loose, you might have an air leak through there that could be the source of the idle problem.

[ak_907_ak]

Originally Posted by kkim

check the clamps that hold the carbs to the cylinder head on the rubber manifold thingy. if they are loose, you might have an air leak through there that could be the source of the idle problem.

When I just put my bike back together, I triple checked that those are one all the way. The each rubber tube, there is also a Cylinder side and a Carb side.

As for the fuel stabilizer, I added stabil when i put it in storage for the winter, is that what your talking about? I should still have some left.

[kkim]

try to find some Seafoam, if you can. just add some to your gas.

[ak_907_ak]

[QUOTE=kkim;67587]try to find some Seafoam, if you can. just add some to your gas.

I used that stuff before on my car, makes a huge cloud of white smoke.
i will put it just in gas, but it can also be put in the crankcase(oil) and one more place, i forgot.

[kkim]

yep, gas, crankcase and directly into the intake port by using a vacuum line. You want to get the seafoam into the carbs, which is why I suggested putting it into the gas.

have used it on a number of my older cars/trucks and yes... it makes a HUGE cloud of white smoke when inhaled through an intake vacuum port.

[ak_907_ak]

next sunday, i will try to get some seafoam by friday, and sunday, if the foam doesn't help, ill take it apart look at the pilot jets.

[Banzai]

Originally Posted by Buffalony

Sorry to go off topic: So the fuel gauge can be fixed to work normally?

Yes, but it requires replacement of the bad sender with a good one. That's the only thing that will cure it's issues. There is bad quality control in the manufacture of the sense coil and the button/wiper assembly that make up the sender unit. Other than the shape of the tank, this is what causes the extreme non-linear function and indicating AFU levels.

I'll do a write up here shortly. I have a bad sender that I'll open up and show you all what's going on inside it and why it's bad and what else goes wrong with them.

[Buffalony]

Originally Posted by Banzai

I'll do a write up here shortly. I have a bad sender that I'll open up and show you all what's going on inside it and why it's bad and what else goes wrong with them.

Sounds good

[ROADandTRACK]

Sea Foam is a waste, just ake 'em apart and fix it. Takes less than 2 hours.