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Discussion Starter #1
*Again, i'm a newb to bikes and carb'd vehicles, so even if you think i'm missing something pretty obvious, PLZ let me know*

Bought the bike about a month ago now, and when the bike is warming up (part choke) or fully warmed (no choke), when i engage the clutch the revs will quickly rise up and idle around 5k. I let the bike warm up in my garage yesterday while a played with the throttle, and while the bike is warming up i can blip the throttle and then the revs will start to drop down to 1500rpm, but then build right back up to ~5k. When the bike is fully warm, i can't really even get the revs to drop below 4k in neutral...

After i blipped the throttle, i watched the throttle at the carbs and it seems to be tensioned correctly, seems as if the plates are closing completely...

The plugs are probably pretty old (i didn't measure the gap, and i don't even think they were NGKs :icon_frow ), and i haven't checked the condition of the air filter...

I'm in MI, so i haven't been able to see the bike run at anything over 40*F yet, but she seems to run great except the idle issue...

Any help/suggestions are VERY appreciated, thanks in advance guys/girls :)
 

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RideOrDieWarren
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652 Posts
First off get new plugs, if they are not NGK's, most likely Champions. Take them out before they melt and cause more problems.

Need history of bike. Year, mileage, maintenance history.

Carbs prob need cleaned, carb sync (symptom same as mine and this fixed it), oil/filter change, good battery (buy yourself a multimeter; Actron from Autozone $20, has a .01v error, awesome).
 

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Did you try adjusting the idle down after the bike is warmed up? When I first had my 500R the rev's never went down below 3k and it wasn't 'til two weeks later in a forum after I asked that someone suggested that I adjust the idle after the bike is warmed up. Never had idle problems again.
 

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Discussion Starter #4
haha, sry love2ride

'02 ex250 with ~10k miles, don't know much of the history other than it has had a rough life and is now a streetfighter, lol.

I already bought a new battery for it, I have a good DVOM (i'm an Automotive major), and that oil was changed by the previous owner after last winter, but hardly ridden last year. I was going to change the oil/filter after winter

'Carb sync' meaning that the two carbs are not opening in-time to eachother? Any way to test this other than a visual inspection (the throttles seemed to be timed...)

Did you try adjusting the idle down after the bike is warmed up? When I first had my 500R the rev's never went down below 3k and it wasn't 'til two weeks later in a forum after I asked that someone suggested that I adjust the idle after the bike is warmed up. Never had idle problems again.
Would the idle adjust happen to be the black knob to the left of the carbs? I was thinking thats what it was and messed with it a little bit yesterday, but didn't want to screw anything else up, lol. I just thought it was odd that i could blip the throttle and it would rev down to 1500, but then build right back up w/o the throttle plates moving...

Could the carb-to-head boots cause something like this to happen? Mine are wrapped in duct tape, so I figured they might have holes in them or something, but i couldn't feel any vacuum leaks...

Thx for the suggestions, keep 'em coming!
 

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RideOrDieWarren
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Warm the bike up and turn that black knob. I think counter is decrease, clockwise is increase.

Rough life. Maint prob not completed when it needed it. 250's are tempermental. They need tlc or else.

Carb sync is something like that. Open in sync with eachother so both carbs are getting fuel and air in same amount. If not in sync then idle will be high and very slow to return to idle if it even does.
 

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RideOrDieWarren
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The valves tighten on the 250, but it does not give you the symptons you are having. They would give you the opposite, bike dies at idle.
 

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The valves tighten on the 250, but it does not give you the symptons you are having. They would give you the opposite, bike dies at idle.
It would still be best to go through everything on the bike not knowing the prior history and then be able to better diagnose it

quote ive heard - when buying a used bike always asume its never been done...
 

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Discussion Starter #11
i was able to keep the idle down by simply turning the idle-adjust down as the bike was warming up. Thanx guys
 

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It sounds to me like you have alot of maitenence to do on that bike. Go to the Ninja250 site link mentioned above and print out all the detailed directions there. Were it me, the first job to tackle would be the valve job (and change the plugs while you're doing this job). Then follow their directions and build a little carbsync setup (the two bottles with stoppers method) -and do that carbsync check. Maybe run a tank with a few ounces of seafoam added. NOW warm it up and set the idle knob and see where you're at with that bike...

Just my .02 ;)
 

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Discussion Starter #13
It sounds to me like you have alot of maitenence to do on that bike. Go to the Ninja250 site link mentioned above and print out all the detailed directions there. Were it me, the first job to tackle would be the valve job (and change the plugs while you're doing this job). Then follow their directions and build a little carbsync setup (the two bottles with stoppers method) -and do that carbsync check. Maybe run a tank with a few ounces of seafoam added. NOW warm it up and set the idle knob and see where you're at with that bike...

Just my .02 ;)
yea, I know I have my work cut out for me ;) I'm trying to find the long feeler gauges that were recommended on ninja250 for the valve adjustment, I think I'll check out jegs.com (where I ordered my other feeler gauges from)

It's not very fun having to work on stuff when we have about a foot of snow, 4 cars, and an un-heated 2 car garage (and my dad's S2000 isn't going to move from the garage, lol).
 

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...It's not very fun having to work on stuff when we have about a foot of snow, 4 cars, and an un-heated 2 car garage (and my dad's S2000 isn't going to move from the garage, lol).

No excuses accepted, bundle up and "get er dun" :tongue:

Heh, if I can commute with temps in the low 20Fs (expected here for the next few days) -then I KNOW you can show that bike some love during your winter snow days :lol:
 

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Discussion Starter #15
No excuses accepted, bundle up and "get er dun" :tongue:

Heh, if I can commute with temps in the low 20Fs (expected here for the next few days) -then I KNOW you can show that bike some love during your winter snow days :lol:
lol, yea, I'll get the ambition to do all the maintenance before spring hits.
 

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It is possible to do a valve job on the 250 with standard length feeler gauges if you take them out of the stack. Just be careful not to drop them down the right side of the engine by the timing chain.....not that I would know anything about doing that....:oops: It is, however, a whole lot easier to do if you have Kawi's valve adjustment tool. If you plan on keeping the bike for a few years, it's $50 well spent.
 

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It sounds to me like you have alot of maitenence to do on that bike. Go to the Ninja250 site link mentioned above and print out all the detailed directions there. Were it me, the first job to tackle would be the valve job (and change the plugs while you're doing this job). Then follow their directions and build a little carbsync setup (the two bottles with stoppers method) -and do that carbsync check. Maybe run a tank with a few ounces of seafoam added. NOW warm it up and set the idle knob and see where you're at with that bike...

Just my .02 ;)

That bloke has similar problems to mine....same bike, rough condition and idling wrong.....what does Seafoam do....is it a product or do I go to the coast and get some foam??? (now that sounds dumb...sure hope it's a product)
 

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Seafoam is a fuel additive that, among other things, dissolves the varnish left in the carbs when gasoline evaporates. If you carbs are only a little dirty, as opposed to "tear them down completely because they don't work at all" dirty, running a bit of Seafoam mix through the bike can help clear things up.
 

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Seafoam is a fuel additive that, among other things, dissolves the varnish left in the carbs when gasoline evaporates. If you carbs are only a little dirty, as opposed to "tear them down completely because they don't work at all" dirty, running a bit of Seafoam mix through the bike can help clear things up.

might have to hunt that stuff down......have been looking for something like that but cant find any at the local auto shops
 

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