Idle issues

[Gyrene]

I am unable to get my bike to idle steady, cold or warm. When I start it cold and put the choke on it hits 4500-5000 RPM then when I slowly take the choke off it will idle at 1500-2000 then slowly climb back to 4000-5000. I adjust the idle screw to get the RPM down to 1500 and it will slowly climb back up again. When I adjust the idle screw to bring it down it comes down to a decent level then rises again. When I twist the throttle to bump the RPMs it will go from 1500 to 3500-4000 then slowly come down again. Twisting the throttle never gets a typical response you would expect in a quick rev, instead it goes up in RPM quick by will only slowly come down. I would expect the RPMs to rise and fall at the same rate.

Any ideas what I am dealing with here? Remember I am new to motorcycles so keep it simple if you can.

Thanks

[mrlmd]

The rpms do not rise and fall at the same rate. It can go up real fast when you rev the throttle and comes back down slower when you back off the throttle. That's normal.

There may be a few reasons for your idle "problem", but let me ask you for some more information first, about the bike and also regarding the choke and exactly what you are doing.
First off, was the bike fine before, and this is a new problem or was it always like this? Is this bike new to you, a recent purchase? Is this the first spring startup after being stored a while or has it been ridden frequently?

Are you slowly turning the choke down as the bike warms up, or are you messing with the idle adjustment before the bike has fully warmed up? Idle adjustments should be made when the engine is at normal operating temperature, ie, fully warmed up. And after they are set, they are left alone.

Are you using full choke for startup? It's not that cold in Florida now.
Use your choke when starting to set the rpms about 3000 or so and if the engine runs without stalling, turn it down a tad and start riding slowly away. As the bike warms up, gradually back it off after a min or so, then slowly get it all the way off. No need to rev it to 4500-5000 to warm it up initially and letting it idle until it is warm is not that good an idea. You are probably using too much choke and don't try to adjust any idle mixture with that much choke and a cold engine.
If you keep trying to adjust things, being new to motorcycles, you may get yourself into a situation where the only solution may be to take it in to a shop after it gets way out of adjustment because it gets real difficult to figure out online what's going on. One thing at a time makes it much easier.
We can help you figure this out after we get more information from you. Try what I said first and see what happens.

[kkim]

sounds like you might have a vacuum leak. check the vacuum hoses to see if one of them may have slipped off or is cracked.

btw, the idle speed should be set after the bike has been completely warmed up.

[Gyrene]

Any idea where I can find those?

[Snake]

You can get replacement vacuum hoses at any auto parts store.

[kkim]

Originally Posted by Gyrene

Any idea where I can find those?

those what?

as asked by mrlmd, are you sure you are using the choke correctly? is this something new or has the bike always had this problem?

[Gyrene]

Sorry, didn't see the other response.

The bike was just bought and has been like this since I got it. I was advised that it was not ridden much other then once a week to make sure it ran. I was also advised that it needs a valve adjustment but the local service shop said that has nothing to do with the idle.

I do not adjust the idle set screw until fully warmed up. When I do start it I adjust the choke to get it to 3000-4000 RPM but after it warms up and choke is off is when it will rise and fall in RPMs on it's own at varying intervals.

If I do not adjust the idle set screw the RPMs will rise to 5000 and stay there for a good 20-30 seconds before coming back down. Sometimes it will fall to the point of the bike stalling, other times it will get as low as 500 RPM before rising again.

I hope this helps.

[Gyrene]

Originally Posted by Snake

You can get replacement vacuum hoses at any auto parts store.

I meant where I can find them on the bike. I don't even know where to start looking for one.

[kkim]

you will need to remove the fairings to get to the vacuum hoses. are you willing/capable of doing that? if not, perhaps this would be best left to a shop.

btw, how many miles on the bike and when was the last time the valves were adjusted?

[Gyrene]

Milage on the engine is unknown. It is a replacement motor for one that was blown. This engine was installed a few months ago.

I do not know when a valve adjustment was last done. I do feel comfortable removing the fairings and can do it if I need to.

[Gyrene]

I already contact a local shop about the valve adjustment and it is going there in 3 weeks to have it done. I may just have them look at the carbs as well.

[kkim]

in the mean time, if you feel comfortable doing so, remove the lower fairings and look around near the carbs for any loose hoses.

http://faq.ninja250.org/wiki/Bodywork_%26_Frame

http://faq.ninja250.org/wiki/Intake

[mrlmd]

This problem should have nothing to do with a valve adjustment.
Try running some carb cleaner like Seafoam or Berryman's B12 or Gumout at the proper dose or double the dose in your gas and see if that fixes it.
A vacuum leak is a possibility, or something sticking in your linkage. You can check everything around the carbs when you remove the fairings. Lube the cables while you are at it, make sure nothing's ginked.
Kawasaki recommends an idle speed of 1300 rpms, so you are a little high but that's OK.

[Gyrene]

Yeah, I am going to try the SeaFoam stuff and see if it resolves it before it goes in to the shop for the valve adjustment. If it does not resolve it then I will have them look at it.

[HotWheels]

I saw a lot of people pointing towards a vacuum leak of some kind which could very well be the case how ever I did not notice anyone suggesting that you check the black rubber boots from, the air box to the carb and from, he carb to the engine. It is possible that perhaps they are not tight enough and or a proper seal was not made with them when re installation occurred. This is a common problem sometimes. I would def check those to make sure they are seated correctly and tightened adequately.

[Gyrene]

I took the bike for a 100 mile ride today and it is not as bad as I thought. I think it may have been dirty carbs that are now getting flushed out with the new gas I put in. After riding today it now idles pretty good between 1000-1500 after some tweaking of the idle screw. It occasionally will jump up to 3000 when sitting at a red light but releasing the clutch into the friction zone drops it right back down to 1000-1500.

I am still going to have the local shop clean the carbs when they do the valve adjustment just to be thorough.