trouble with idle

[james250ninja]

hi there I am having trouble setting my rpm idle.

I just did a full clean on my carbs .I cleaned the main jets the pilot jets real good cleaned the carbs thoughly.
I installed them bike into the bike .no air leaks everything sealed tight. The floats are set properly.

I've done this before and had no problem with the bike starting up.

now when I start it up just cant seem to find the right rpm idle for the bike I turned the knob each way so many times. now I lost track on where it was set at the start.

any ideas on what I shoud do

[Triple Jim]

Are the valves adjusted within spec?

[jkv45]

You didn't mention the idle mixture screws. Did you remove them, clean the passages, and make sure the o-rings are in good condition and installed correctly before setting them to a base of 2.5 turns out?

Did you bench sync the carbs when they were off?

I like to adjust the idle mixture screws to get the highest RPM, then go richer (out) until you hear it just begin to drop (usually about 1/8 turn).

Then after a full warm-up, set the idle to 1300 using the idle speed knob.

[Triple Jim]

Originally Posted by jkv45

Then after a full warm-up, set the idle to 1300 using the idle speed knob.

I'm sure you meant it this way Jay, but you need to have the engine fully warm before doing any of the carb adjustments.

[jkv45]

Originally Posted by Triple Jim

I'm sure you meant it this way Jay, but you need to have the engine fully warm before doing any of the carb adjustments.

Right - good point.

In order to make the idle mixture adjustments it does need to be fully warm as well.

Thanks for catching that TJ.

[asellus]

When you say "you can't find the right idle" -- what exactly do you mean?

When I first got my 250, it would idle either at 1k rpm or 2k rpm. Both were relatively rough. Setting it to anything in between would cause it to hunt between the two.

My valves were out of spec (400 miles overdue for clearance adjustment), and the main jet on the right carb was unscrewed 3-5 turns, so it was basically full blast. My idle mixture screws were also not at the 2.5 turns out 'base' -- they may have been tuned at one point, but I reset them when I took it all apart.


You can see the idle screw actuating the throttle if you look at the right side of the carb. I don't know how many turns against the lobe once it contacts it "should" be, but you can back it out until it stops making contact to get a feel for when turning it will start to have an effect.

Hope that helps.

[ducatiman]

If original...OP's '86 should have the older 32mm, metal slide Keihin CV's.

Have the pilot screw "anti-tamper" caps been removed? Pilot screws, springs, washers and tiny orings removed for cleaning (along with the pilot jets)? Then replaced in correct order? Set at 2.5 turns starting point?

If this is the case...other internal carb issues exist.

What cleaning and flushing methods were used during your clean procedure?

Agreed, 250's valve clearances are a critical tuning parameter.

[highvoltj]

Hey James... Nice '86!! Look's just like mine!!
I had idle issue's when I first got my '86 Ninja, make sure both throttle cables are gliding like butter in the cable housing's...throttle snapping back to close quickly with no hesitation...also valves adjusted to spec's, visual sync of throttle plates and both mixture screw's turned out the same amount...initially 2.5 ..warm up and turn out till smooth operation...mine are set at 3 turns out.. but I also have 2 into 1 Muzzy, Pod's and a Jet-kit installed...
Hope this helps!

[james250ninja]

hi there
I used carb cleaner and cleaned the entire crabs
I reset the idle mixture screws. so I turned them 2.8

I bought the bike with 6000 miles and the valves were done at that point at 6000 miles the first owner did a tune up and valve adjustment.

I recently did oil change spark plugs while I cleaned my carbs.


may I ask you would it hurt to put a set of carbs from a 1988 -2007 ninja 250 models in our 86 models.

[highvoltj]

James...why would you want to do that? The '86-'87 use 32mm carbs, whereas the newer models use 30mm carbs...I wouldnt replace unless there is something physically wrong with them!

[ducatiman]

the 88-07 carbs are 30mm...will physically interchange, bolt directly in, cabling same

Performance running the smaller carbs? Jetting changes required? Unknowns... incumbent on you to test. I know for a fact the 86 vintage and 88-on vintage ARE jetted differently.

31 year old carbs you got there...extreme cleaning measures are called for, beyond carb cleaner spray. Did the bike sit, unstabilized fuel, over the winter?

As an aside...I could never trust a PO/seller claiming "valves were done".
I'd strongly suggest a clearance check to set YOUR *known, verified * service baseline, no secret these things are so sensitive to tight valves.

Is this 86 just purchased by you at 6000? So how many miles now? Has the bike run correctly during the span of your ownership?

[highvoltj]

DUCATIMAN Nailed it!!

[Triple Jim]

The reason I asked about valve adjustment is that I have firsthand experience with misadjusted valves. It was impossible to get the idle speed right with my '05 250 when I bought it used. When cold, it wanted to idle at about 2,500-3,000 rpm, or when adjusted slightly slower, would slow down and stall. When warm, the symptoms largely went away, as the valve clearances grew slightly. I had to turn the idle up to be able to ride away from the house, and then adjust it back down later so it wasn't screaming at stop signs and traffic lights. After adjusting the valves, everything was suddenly OK.

If your valves are not adjusted correctly, you'll be chasing carburetor problems forever.

[jkv45]

Originally Posted by james250ninja

hi there
I used carb cleaner and cleaned the entire crabs
I reset the idle mixture screws. so I turned them 2.8

I bought the bike with 6000 miles and the valves were done at that point at 6000 miles the first owner did a tune up and valve adjustment.

I recently did oil change spark plugs while I cleaned my carbs.


may I ask you would it hurt to put a set of carbs from a 1988 -2007 ninja 250 models in our 86 models.

Never trust work done by the PO...

It sounds like the carbs need to be cleaned and adjusted professionally (hello ducatiman...) and the valves checked.

Then you could cross those items off of the list and move on, but most likely you'd be ready to ride after that.

[asellus]

Originally Posted by Triple Jim

If your valves are not adjusted correctly, you'll be chasing carburetor problems forever.

This. A thousand times this. You're not going to find that 1300 idle speed with valves out of clearance.

If you're even close to due for the valve adjustment, just do it. It's relatively easy, even without the special tool. The only real tough part is access to the inner cams -- a long go/no-go feeler gauge is wonderful here. Other than that, follow the instructions closely and even the most inexperienced folks can do it, so long as they understand how a feeler gauge works. :]

I did mine while distracted by the neighbour talking to me over the course of about an hour, then moved on much more confidently to the carbs knowing the engine was in spec.

[james250ninja]

I rode during the winter when it didn't snow.

ok I wont change carbs from 88-07 .jut thought id ask

I started it up twice a week in the winter.

ok I figured out the ide adjustment.

when the bike fully warmed up I set it at 1100 rpms, but it like hunting for the right idle.
it will jump a bit to 2000 rpms then back to 1100 rpms.

[james250ninja]

I bought the bike with 6300 miles for $1600.00

it rode great all the time
still rides great.

every time I clean the carbs it runs great.
just now I need to find the right idle. But I think I am almost there.
my idle jumps from 1100 to 2000 when fully warmed up..
that the only thing I am trying to get right. I took it out today and open it up and rides great through all the gears

[asellus]

Right, and that's more or less what's going to happen if your valves are a bit out of spec, your idle mixture is off, or your jets are stuck a little open. It'll be happy above idle.

The thing you need to be wary of is that if your valves are floating all the time, you will burn them. Part(most?) of their ability to dissipate heat is through the seats, which they slowly stop contacting over time. Hence the need for valve adjustments.

It was said before and it's absolutely true -- never trust maintenance by the previous owner. If a reputable shop did it and there are receipts that's one thing, but otherwise.. nope. Cracking it open to check isn't a lot of work, and adjusting them from there is only a couple more minutes.

[jkv45]

Originally Posted by james250ninja

every time I clean the carbs it runs great.

That suggests you are getting junk from the tank flowing into the carbs.

You need a good inline fuel filter.

After cleaning and adjusting the carbs you should be good unless you let it sit a long time or have debris from the tank plugging it up.

[james250ninja]

is a valve job difficult..kind of intimidated by doing a valve job.
where do I get a valve clearance tool.

[asellus]

Difficult, no. Precise and tedious, yes. I may be biased since this is not a new concept to me, so YMMV. I believe anyone can do this if they are capable of reading and following directions. Give this a read:
http://faq.ninja250.org/wiki/What_is...t_procedure%3F

You can get feeler gauges from most auto parts stores, your local Sears, snap-on dealer, mac dealer, Amazon, etc.. I'm partial to go/no-go gauges, since you have to flip between gauges way less that way.

[Triple Jim]

Be aware that the term "valve job" normally refers to removing and disassembling the head, machining the valve seats and valves, possibly replacing bad ones, and reassembling. It's done when the valves start getting leaky. We're talking about adjusting valve clearances, often called "valve adjustment".

[highvoltj]

Hey James, if you haven't done the valve job yet, I wanted to tell you that it is quite easy on the '86. I went and bought a set of "wobble" extensions at Harbor Freight, and using the 1/8" short extension with a 10mm (0r was it 11mm?) I was able to get right in there to crack the jamb nut loose to adjust clearance studs to proper clearance...again, you will have to get a socket on the rotor to turn the engine over (spark plugs removed is easier) align the timing marks and adjust accordingly...take your time, and your motor will be happy....prior to doing this, my '86 was surging at idle as well. It was also very helpful to bench sync the throttle plates to get a more accurate adjustment of where they are opening and closing. I then went about re-jetting my carbs for optimum performance after removing stock airbox for K&N pod's and 2 into 1 Muzzy....she runs like a Champion now!!
Happy Motoring!!!

[ducatiman]

Valve clearances essential to proper starting/running on ninjettes..Many folks intimidated by the "complexity" of the procedure....blow it off.

In denial, wondering why hard starting....chasing ghosts.

Any "new to you" non-runner purchase should be accompanied by an immediate valve clearance check. I believe there are multiple "won't start" threads ongoing here...members have rightfully suggested checking. Its imperative!