Idle speed

tdecotis · November 13th, 2013, 01:20 PM

First thing is that when I start the bike after a day of not riding the bike starts up and then dies. I notice that the RPM's are less than 1k when this happens. All I need to do is apply a little choke and let it run for a minute and when I release the choke all is fine and the bike runs.

Next issue is that when just beginning to ride the idle speed is around 1.2 rpm's but then after riding for a while it will jump to 3 or 4. I have checked for vacuum leaks using the carb spray on all 4 boots but don't see any change in the idle speed. I really thought this was the issue but now I have no idea or maybe there are other places to check for a leak.

I have also messed with the idle adjuster screw countless times after riding the bike for 15 minutes to make sure the engine is warm to get it to the 1.2 rpm's but the problem still persists.

I have also lubed the throttle cables recently because I thought they might be sticking.

Any questions, comments, or ideas would be helpful. Thanks.

csmith12 · November 13th, 2013, 01:28 PM

Time for a carb cleaning

. Something is sticking somewhere when it gets warm/hot enough. You could try some seafoam or the sorts but doubt it will help. My gut is telling me to let you know to check for carb sync too. Not sure why.

ktp1598 · November 13th, 2013, 01:51 PM

Sticky slide?

tdecotis · November 13th, 2013, 01:53 PM

Quote:

Originally Posted by csmith12

Time for a carb cleaning

. Something is sticking somewhere when it gets warm/hot enough. You could try some seafoam or the sorts but doubt it will help. My gut is telling me to let you know to check for carb sync too. Not sure why.

Thanks for the response. I recently cleaned the carbs as well. I did not sync them though since I don't have the tool. I will try to get my hands on a sync tool and see if that fixes the problem.

tdecotis · November 13th, 2013, 02:12 PM

Quote:

Originally Posted by ktp1598

Sticky slide?

I will attempt to look at this as well but it was just a few weeks ago that I took the carbs completely apart and cleaned them so I don't know that they would be sticking.

ktp1598 · November 13th, 2013, 02:24 PM

Could also be something like the vacuum line to the petcock. A small split in the line might be able to do this but be hard to see. May do good to replace all vacuum lines depending on their age anyway.

jkv45 · November 13th, 2013, 02:47 PM

Quote:

Originally Posted by csmith12

Time for a carb cleaning

. Something is sticking somewhere when it gets warm/hot enough. You could try some seafoam or the sorts but doubt it will help. My gut is telling me to let you know to check for carb sync too. Not sure why.

This is what I'm thinking also.

tdecotis · November 20th, 2013, 09:52 AM

I was able to clean the carbs again and even sync them. The problem still persists though. My next idea was maybe the air filter. Is that possible?

Lychee · November 20th, 2013, 12:05 PM

Has this bike run well in the past or is it a new problem / new to you bike?

tdecotis · November 20th, 2013, 12:19 PM

Quote:

Originally Posted by Lychee

Has this bike run well in the past or is it a new problem / new to you bike?

Unfortunately this is a bike that was sitting in a friends garage for a few years that I decided to buy and fix up. It was not running when I got it. It had bad spark plugs, I took the carbs apart cleaned and synced, changed oil, coolent, etc..

I took it for a ride earlier and can get the idle speed back down when I pull the clutch in but other than that it tends to idle high.

jkv45 · November 20th, 2013, 12:36 PM

Does it still run good with the choke on? That's usually a sign of clogged jets.

Did you remove all of the jets and clean them carefully? How about the float height? Did you set the idle mixture screws at 2 1/2 turn out and confirm the washers and o-rings are good?

If the air filter looks good I don't think it's an issue.

Check for a vacuum leak around the carb boots.

tdecotis · November 20th, 2013, 12:45 PM

Quote:

Originally Posted by jkv45

Does it still run good with the choke on? That's usually a sign of clogged jets.

Did you remove all of the jets and clean them carefully? How about the float height? Did you set the idle mixture screws at 2 1/2 turn out and confirm the washers and o-rings are good?

If the air filter looks good I don't think it's an issue.

Check for a vacuum leak around the carb boots.

I have checked for vacuum leaks and there is no change in RPM's (using carb cleaner to spray around all boots)

When I cleaned the carbs I removed all the jets and cleaned the very tiny holes and made sure they were all clear.

I did not check the float height or idle mixture screws but that is what someone said in another forum I just looked at. They said idle mixture screw not set right was one of the main problems for high idle speeds.

I will check the idle mixture screw. What is a proper float height?

**Just took it for another quick ride and when it started to idle high I stopped and pulled in the clutch almost to the point of letting the bike stall out. I tried it a couple of times and it went back down to regular idle.

jkv45 · November 20th, 2013, 02:06 PM

Quote:

Originally Posted by tdecotis

I have checked for vacuum leaks and there is no change in RPM's (using carb cleaner to spray around all boots)

When I cleaned the carbs I removed all the jets and cleaned the very tiny holes and made sure they were all clear.

I did not check the float height or idle mixture screws but that is what someone said in another forum I just looked at. They said idle mixture screw not set right was one of the main problems for high idle speeds.

I will check the idle mixture screw. What is a proper float height?

**Just took it for another quick ride and when it started to idle high I stopped and pulled in the clutch almost to the point of letting the bike stall out. I tried it a couple of times and it went back down to regular idle.

There is a way to check the float height with the carbs on the bike using clear tubing, but I've not done it. Usually you do it with the carbs off.

Take the air filter out and reach inside the airbox. Lift the slides with your finger and let them drop - do they rise and fall smoothly? Does the throttle snap back quickly and firmly when you release it?

Set the idle mixture screws 2 1/2 turns out, slightly more in cold weather.

Lychee · November 20th, 2013, 02:30 PM

Valve adjustment? These bikes have valves on rockers that like to tighten up over time. If they get too tight the valves never close.

The correct float height is 17mm +-2mm.

http://faq.ninja250.org/wiki/How_do_..._the_floats%3F

Personally, I think the method using the clear tubing is only good for a gut check. You attach clear tubing to the drain hole and bend it upward so that the end of the tube is higher than the height of the fuel in the carb. Then you unscrew the drain plug and allow the fuel in the bowl to go into the tube. Theoretically the height measured in the tube should be similar to the height inside the bowl.

tdecotis · November 22nd, 2013, 10:47 AM

Thanks again everyone. I realized that when I cleaned the carbs I screwed in the idle mixture screws all the way. I was able to reset them and the bike seems to be running the best it has since I got it.

November 13th, 2013, 01:20 PM	#1
tdecotis ninjette.org member Name: Tony Location: FL Join Date: Sep 2013 Motorcycle(s): 05 Ninja 250 Posts: 23	Idle speed First thing is that when I start the bike after a day of not riding the bike starts up and then dies. I notice that the RPM's are less than 1k when this happens. All I need to do is apply a little choke and let it run for a minute and when I release the choke all is fine and the bike runs. Next issue is that when just beginning to ride the idle speed is around 1.2 rpm's but then after riding for a while it will jump to 3 or 4. I have checked for vacuum leaks using the carb spray on all 4 boots but don't see any change in the idle speed. I really thought this was the issue but now I have no idea or maybe there are other places to check for a leak. I have also messed with the idle adjuster screw countless times after riding the bike for 15 minutes to make sure the engine is warm to get it to the 1.2 rpm's but the problem still persists. I have also lubed the throttle cables recently because I thought they might be sticking. Any questions, comments, or ideas would be helpful. Thanks.

November 13th, 2013, 01:28 PM	#2
csmith12 The Corner Whisperer Name: Chris (aka Reactor) Location: Northern KY Join Date: May 2011 Motorcycle(s): 2010 250 (track), 1992 250, 2006 R6 (street/track), 2008 R6 (track) Posts: Too much. MOTY 2015, MOTM - Nov '12, Nov '13	Time for a carb cleaning . Something is sticking somewhere when it gets warm/hot enough. You could try some seafoam or the sorts but doubt it will help. My gut is telling me to let you know to check for carb sync too. Not sure why. __________________________________________________ Goal: Shake A Million Hands \| Look through the corners \| Track Day Prep \| Closest track? \| The Mid-Ohio School

November 20th, 2013, 12:05 PM	#9
Lychee sail away Name: Jon Location: San Jose Join Date: Jul 2012 Motorcycle(s): gixxer (sold), ninjette (upgrade!) Posts: 964 Blog Entries: 8	Has this bike run well in the past or is it a new problem / new to you bike? __________________________________________________ Unregistered found this post helpful. Track Day Preparation Checklist 1. Financial 2. Mental 3. Physical 4. Gear / Bike

November 20th, 2013, 02:30 PM	#14
Lychee sail away Name: Jon Location: San Jose Join Date: Jul 2012 Motorcycle(s): gixxer (sold), ninjette (upgrade!) Posts: 964 Blog Entries: 8	Valve adjustment? These bikes have valves on rockers that like to tighten up over time. If they get too tight the valves never close. The correct float height is 17mm +-2mm. http://faq.ninja250.org/wiki/How_do_..._the_floats%3F Personally, I think the method using the clear tubing is only good for a gut check. You attach clear tubing to the drain hole and bend it upward so that the end of the tube is higher than the height of the fuel in the carb. Then you unscrew the drain plug and allow the fuel in the bowl to go into the tube. Theoretically the height measured in the tube should be similar to the height inside the bowl. __________________________________________________ Unregistered found this post helpful. Track Day Preparation Checklist 1. Financial 2. Mental 3. Physical 4. Gear / Bike

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November 13th, 2013, 01:51 PM	#3
ktp1598 ninjette.org member Name: Bobby Location: Mount Washington Ky Join Date: Nov 2013 Motorcycle(s): 2007 Ninja 250 Phantom Silver, 2006 Harley Davidson XL1200L Glacier White Posts: 28	Sticky slide?

November 13th, 2013, 02:24 PM	#6
ktp1598 ninjette.org member Name: Bobby Location: Mount Washington Ky Join Date: Nov 2013 Motorcycle(s): 2007 Ninja 250 Phantom Silver, 2006 Harley Davidson XL1200L Glacier White Posts: 28	Could also be something like the vacuum line to the petcock. A small split in the line might be able to do this but be hard to see. May do good to replace all vacuum lines depending on their age anyway.

November 20th, 2013, 09:52 AM	#8
tdecotis ninjette.org member Name: Tony Location: FL Join Date: Sep 2013 Motorcycle(s): 05 Ninja 250 Posts: 23	I was able to clean the carbs again and even sync them. The problem still persists though. My next idea was maybe the air filter. Is that possible?

November 20th, 2013, 12:36 PM	#11
jkv45 Rev Limiter Name: Jay Location: WI Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot. MOTM - Jun '18, Oct '16	Does it still run good with the choke on? That's usually a sign of clogged jets. Did you remove all of the jets and clean them carefully? How about the float height? Did you set the idle mixture screws at 2 1/2 turn out and confirm the washers and o-rings are good? If the air filter looks good I don't think it's an issue. Check for a vacuum leak around the carb boots.

November 22nd, 2013, 10:47 AM	#15
tdecotis ninjette.org member Name: Tony Location: FL Join Date: Sep 2013 Motorcycle(s): 05 Ninja 250 Posts: 23	Thanks again everyone. I realized that when I cleaned the carbs I screwed in the idle mixture screws all the way. I was able to reset them and the bike seems to be running the best it has since I got it.