02 Runs rough below ~3500 RPM

[SV_Hadder]

The bike runs perfect except for below 3500 rpm. It feels like its only running on 1 cylinder below 3500 and then the 2nd cylinder kicks in at 4000. It won't idle below 1500rpm. Below 1500 it starts to clank and then dies.

I emptied the float bowls and got some red-ish sediment and what looked like other debris. I cleaned these carbs thoroughly about 1 year ago. The bike has been running perfect for the past 4,000 miles. WTF

Could it be electrical problems? If the bike is at 1500 revs and I hold constant 1/8 throttle it runs rough and stumbles its way to ~4000 and then it clears up... If it was a pilot jet problem it would run rough past 4k even if I was holding constant 1/8 throttle, right?

I may just tear the damn carbs apart, but thats not really what I had planned for this weekend, ya know? Anything else it could be guys?

Thanks

[choneofakind]

Try adding Seafoam to the gas. Pilot jets get gunked up easily. If it gets better, you can either ride it as is, or take them apart and do a more thorough clean. Plus adding the seafoam now will make cleaning the carbs easier if you decide to clean them later

[SV_Hadder]

Seafoam saved the day! I put in about half a bottle of the stuff and it started clearing up. I think I'll pour some in every month or so just to make sure everything stays free and clear.

[Alex]

[choneofakind]

glad it worked

thats what I end up doing with my bike too. I add carb cleaner once every 3rd or 4th tank just to make sure that everything is nice and clean

[Socal5646]

Anyone experiment with an inline fuel filter? I was thinking about doing this next...

[SV_Hadder]

The petcock has a filter on the main and reserve tap. There is also a small filter in the fuel feed line.

[choneofakind]

there is?? I only have the filters on the petcock


but just in case you're wondering how to do it,

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

[Socal5646]

Perfect....exactly what I was thinking of!

[JLinde1339]

I've done the fuel filter, as added precaution. I feel better having that. I also pulled the stock filter. Mine is an 01, so wasn't sure what was floating around in that tank. Haven't seen anything on the filter yet, but its nice to know you can just look at it without having to pull the hose and check the filter.
Posted via Mobile Device

[SV_Hadder]

Well, this bike has me stumped... It ran fine for a while, but that didn't last...

I started the bike up last night and let it idle for 3 or 4 minutes, and it ran perfect for those 3 or 4 minutes. THEN, it started running really rough below 3500 rpm. It seems like its only running on 1 cylinder below 3500, and then it clears up past that rpm. I thought maybe pilot jets, but I just cleaned the carbs last weekend to be sure it wasn't. Also, it will run crappy rough at 1/8 throttle or 3/4 throttle, BELOW 3500, so its not a pilot circuit issue. I think I have got it down to being an electrical problem.... the problem is intermittent sort of, and the problem started to occur once the bike was getting up to operating temperature. My best guess is bad coils, because I swapped the igniter box and it made no difference at all. I tried wiggling the spark plug wires and that made no difference.

So I'm on the hunt for 2 coils on ebaymotors, what is the best to get.... Newer model such as 2004-2007 with 10-15000 miles, or any year model as long as the miles are low?

[JLinde1339]

Did you check if the idle mixture screws were set when cleaning the carbs? On mine, the plugs were never removed, and one of the screws was in so tight, I don't think it was getting fuel in one cylinder. And that was how it was set from the factory.
Posted via Mobile Device

[SV_Hadder]

Yeah I definitely checked them a couple of times lol. I drilled the blanks out a while ago, and the screws are set at 2.5 turns out. I tried at 1.5 turns, all the way to 3 turns out, and it made no real difference.

[JLinde1339]

Might want to pull them right out and clean the check those for gunk. I just can't figure out why its fine after 3500. That's usually when the main jet "wakes up". So I'm not sure if there is any electrical reason why it wouldn't kick in till then. I am a self-styled electrotard, so I'd leave that solution to the more adept. The only other thing that I'm not sure you said you checked or not was the spark plugs and possibly the gaps. Other than that, I defer to the electron counters.
Posted via Mobile Device

[SV_Hadder]

I've pulled the pilot screws and checked for any gunk and there was nothing to be found. On that topic, anybody know a good substitute for the small metal washer that goes on the pilot screw? Kinda lost it...

Can anybody else confirm my diagnosis of bad coils? I know I should test them first, but the bike is an hour away and I'm in college full time...

[n4mwd]

Originally Posted by SV_Hadder

I've pulled the pilot screws and checked for any gunk and there was nothing to be found. On that topic, anybody know a good substitute for the small metal washer that goes on the pilot screw? Kinda lost it...

Can anybody else confirm my diagnosis of bad coils? I know I should test them first, but the bike is an hour away and I'm in college full time...

It could be other things besides the coils, but an easy way to test them is to clamp a timing light with an inductive pickup on the plug wires. The light should flash regularly which indicates sparking. Do both sides and compare brightness.

In case you haven't already done this, make sure you aren't using champion plugs in there. Use NGK only.

[SV_Hadder]

Well, as a last resort I went and drained the gas tank and refilled it with known fresh stuff, and it has been running perfect for the past 100 miles or so. Hopefully I just had some bad gas in it, this thing really had me stumped.

Thanks for the help and I hope I won't have to post in this thread ever again!

[SV_Hadder]

I'm back

The weather was nice a few days ago and my GF tried to start her bike, to no avail. I had to get out the jumper cables and starting fluid... Finally got the bike running, and I thought everything was alright. I held the throttle at about 3k until the bike was warmed up, then I let go of the throttle and walked over to the car to unhook the jumper cables, andd the bike died. I thought that was strange, since it was up to operating temp, but nonetheless I figured it would start right back up... WRONG!

After much frustration I got the bike running again, took it out for a ride, and it runs perfect, until I got to a stop sign.. It died, and would not restart.

Sooooo, I'm back to square 1, the bike runs perfect, but will NOT idle or run below ~2500 RPM.

The bike has ~15000 miles, the valves were adjusted to maximum tolerances ~3k miles ago, it has a clean UNI foam filter, the carbs have been gone through twice. I'm gonna replace the spark plugs, and see if that helps at all.

1 thing I forgot to mention earlier, the GF ran the bike low on oil before all this happened, could that have anything to do with this problem?

[DaBlue1]

Could your bike possibly be running too rich on the idle circuit? I see you have a UNI filter, so I assume the carbs have been rejetted?

[choneofakind]

Does it even attempt to crank without being jumped?

If not, get the battery load tested; it's likely d-e-a-d.

[n4mwd]

I think you are correct about it being an electrical problem. (Although it is obvious that you also had a carb problem too.) But instead of component failures, the wiring is more suspect. Check the wiring from the ECU to the coils. And from the coils to the ground. Attached is a wiring diagram that might help. Try flipping the Emergency stop switch back and forth to see if there is an issue there. Look for loose looking flimsy connections.

PS - And as others have said, the bike wont run right with a completely dead battery.

[EMSRacer07]

did u drain the bowls? mine did this when i had some water in there. had water in my tank too i had to get out. make sure the whole system is clear of water and debis. and if u did have troubles with bad gas i would say ur plugs are probably fouled by now. have u changed those yet?

[SV_Hadder]

I bought a brand new battery a few months ago, it works fine and holds a charge, but it took so long to get the bike started that I had to use jumpers.

I definitely want to get new plugs put in, I am going to try and order/pick up some today.

I'll drain the float bowls, and make sure the pilots are at 2.5 turns out.

On a side note, the choke on this bike NEVER liked to work. Full choke would start the bike from cold, it would run maybe 2 or 3 seconds and then die. Half choke did pretty much the same thing. I have got 1 shim under the needle, and that has not helped. I checked the choke passage ways and they were clear. I've had 3 of these bikes, and the choke always worked fine, EXCEPT for this problem child.

[choneofakind]

Originally Posted by SV_Hadder

I have got 1 shim under the needle, and that has not helped.

how rich or lean the needles are has no effect on how nicely the bike idles while cold. Enriching the needles will help your bike warm up quicker only if you warm it up by riding it, where the richer mid-range will help it get to operating temp quicker.

[EMSRacer07]

i say its the spark. get new plugs.

[JLinde1339]

Originally Posted by EMSRacer07

i say its the spark. get new plugs.

I'm starting to think so too. Or at least the gap is too wide. Isn't that about the rpm's where the battery starts to charge? Could be the gap is too wide and the spark won't have enough juice to jump it till 3500...

**meandering thots from an electrotard**
Posted via Mobile Device

[n4mwd]

Originally Posted by SV_Hadder

I bought a brand new battery a few months ago, it works fine and holds a charge, but it took so long to get the bike started that I had to use jumpers.

I definitely want to get new plugs put in, I am going to try and order/pick up some today.

I'll drain the float bowls, and make sure the pilots are at 2.5 turns out.

On a side note, the choke on this bike NEVER liked to work. Full choke would start the bike from cold, it would run maybe 2 or 3 seconds and then die. Half choke did pretty much the same thing. I have got 1 shim under the needle, and that has not helped. I checked the choke passage ways and they were clear. I've had 3 of these bikes, and the choke always worked fine, EXCEPT for this problem child.

Some auto parts places have the NGK plugs in stock. When I got mine they were pre-gapped. Discount-Advance auto parts has them. Just don't get champion plugs.

If you hate carbs, have you seen this fuel injection kit thread? I'm signed up because I hate chokes.

[Skippii]

First of all, never use starting fluid on these bikes. Ever. There's enough spark advance to blow a hole through a piston with starting fluid.

Next...drain the floats next time, and it might start right up.
I've also had a few of these bikes, and my current one is the slowest to start up after sitting for a while, and can take a lot of cranking. I've never killed a battery doing it, but I could see it happening if the choke wasn't working properly. And if your bike starts with full choke and then dies without you touching anything...then yeah...you've got a problem with your choke.

As far as plugs...the stock plugs last for like 70,000 miles, with regapping recommended every 20,000 or so... NGK recommends adjusting the gap about 3 times before replacing the plugs, so it's unlikely that you need to buy new spark plugs anytime soon.