Possible Valve or Carb Issue?

[schmdty420]

I recently bought a used 03 Ninja 250 w/ 14k miles on it. This is my first bike and to me seems like it runs pretty good, but I have noticed a few things that don't seem quite right...First off; the bike has to be at about 3/4 choke to start, and stay there for a few miles of riding or the bike will die. Second; during its "warming up" period (while the choke is on) the RPM's fluctuate up and down. Not by much, but around 1k. Third; I've seen tons of videos where people take off on their Ninjas and easily rap it up to 11k RPM through all gears...My bike sounds like it's gonna explode at around 8-9k, through all the gears. especially 1st through 4th, and sounds to me likes it's revved very high at 9k in 5th gear.
The bike seems to be in excellent shape and the previous owner said it was well maintained, but who knows really. I tried to contact him about whether the valves had adjusted recently or not, but no response...
Could it be the valves are tight? Dirty carbs? I've tried SeaFoam with some luck on performance, but not with the idle. I'm pretty mechanically inclined so tearing into the motor isn't an issue for me. I'm just kind of at a stand-still right now. I don't know whether to tear it down and check out the valves or clean the carbs or both...What do you all think? Any advice would be great. Thanks everyone for any help.

[alex.s]

sounds like combo dirty carbs + needs valves adjusted.

good time to strip her down and clean out everything. change all the fluids (oil, forks, brakes, coolant), pads (clutch, brakes), filters(oil, gas, air) and readjust everything to spec. (cables, valves, linkage, carb sync)

[schmdty420]

Thanks! Thinks valves would cause it to sounds like its gonna explode at 8-9k?
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[alex.s]

haha yes. out of spec valves make it a bitch to start/keep running cold, make it want to explode high up in the revs, make it sound like someones dragging a wooden spoon across a washboard. they screw with compression really bad when its cold. the compression leak also throws off jetting quite a bit depending on different temperatures. if it sounds like grinding / popping on the right side of the case, dont worry too much about that. the kawi cam chains are noisey bastards. you can reset the CCT or get a new one if thats the cause of the noise and it annoys you enough.

[schmdty420]

Awesome! Thank you both. That's exactly what I needed to hear. Looks like I've got a project for this weekend.
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[Jinx250]

Actually, if you adjust the valves to the loose end of spec, the engine is going to be louder.

[davidw38901]

i just did a first time valve adjust.. took about 2 hours... one thing i learned if sitting on bike the ex valve in the upper right hand corner i had to move it off tds on that cyl to get the 9mm in there loosen some.. back to tps adjust... take it off tds tighten....
hope that helps..

[schmdty420]

I appreciate all the help everyone. Gonna do it this weekend. Hopefully everything goes smooth.
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[schmdty420]

Well I did the valves and carbs today...now my little ninja runs like crap.: -( Opened up the carbs and found out someone previously had cleaned them and during reassembly they managed to pinch the edge of both of the diaphragms with the caps. Kind of tore the edge of them up. I took them out and reseated them after totally dousing the carbs with Carb cleaner. Put them all back together, adjusted the valves (too loose now I think) and now she won't even barely idle with the choke on??? Any thoughts??

[alex.s]

the diaphrams maybe damaged. try with throttle. if it runs with throttle turn the idle up and sync the carbs.

[schmdty420]

Yeah it runs when you hit the throttle. Actually is more responsive now. I drove it a few miles, just won't idle. I'll try syncing the carbs tomorrow. Hope that helps. I'm kind of freaking out a bit since it's my daily driver.

[schmdty420]

Is there any easy way to sync the carbs without taking the tank off? And how can I sync them without it being able to idle properly?

[alex.s]

just turn up the idle for now until you sync the carbs

[schmdty420]

Alex, do you think me adjusting the valves too loose would also cause idle issues? They seem to be chattering pretty loudly. I'm gonna fix it tomorrow.

[schmdty420]

Tell me what you think...
https://www.youtube.com/watch?v=qz3f...e_gdata_player

[davenay67]

Originally Posted by schmdty420

Tell me what you think...
https://www.youtube.com/watch?v=qz3f...e_gdata_player

Yeah, they're too loose now. I got my Ninja about 3 weeks ago and did a valve adjustment, carb strip & clean and sync because the bike ran like crap and wouldn't idle.

I adjusted the valves too loose just like yours and they were noisy too. But, the carbs cleaned up nicely and the engine ran great as soon as the carbs were synced. I re-did the valves again this weekend and they are a lot quieter. Re-synced the carbs just to make sure everything is in balance and the bike is running great.

[davenay67]

Originally Posted by schmdty420

Is there any easy way to sync the carbs without taking the tank off? And how can I sync them without it being able to idle properly?

You'd need tiny hands, a small screwdriver and skin with asbestos-like qualities.

It's much simpler just to remove the tank and sync the carbs with a long thin screwdriver from the top.

[schmdty420]

Update: It seems to idling good now right around 1.2-1.5k, you think the valves will be fine if I drive it 20 miles a day for the rest of the week? Or should I fix it ASAP? Thanks for all the input everyone.

[schmdty420]

So...My bike now has a vacuum leak somewhere. Sprayed some starter fluid around the cab this morning and it revved up to almost 7k. Discovered during my carb cleaning that one of the screws is missing from one of the carb bowls...Would that cause anything noticeable?? It was like that before i bought it and didnt seem to cause any problems. Now its running like its lean. Will barely start with the choke on, one i get it to idle and ride a little bit, the idle jumps up to 3k and stays there. And the throttle is not returning to idle when i let off, its hanging...badly. Time to take it off and adjust the idle/air mix tonight i guess. its the one thing i havent tried. Tried to sync the carbs last night but ran out of gas in the bowls before i got it perfect, but they are close. Starting to really get frustrated with this bike.

[davenay67]

Here's what I do when balancing the carbs to prevent running out of gas. This method will buy you as much time as needed to run the engine with the gas tank removed.

I have a small plastic funnel that I plug into the top of the gas line( from the petcock). I then zip-tie the fuel line to the frame so that funnel doesn't flop over and dump fuel. Now all I need to do is keep topping up the funnel every couple of minutes or so from my 1 gallon can that I keep in the garage for the lawn mower.

[davenay67]

Originally Posted by schmdty420

Discovered during my carb cleaning that one of the screws is missing from one of the carb bowls...Would that cause anything noticeable??

Doubtful. Replace the screw when you can, but I don't think it's your problem here.

The main air flow comes from the airbox, and most vacuum leaks come from a leak in the airbox-to-carb rubbers and carb-to engine rubbers. A torn carb diaphragm is another possible antagonist.

You need to be very precise when spraying the carbs so that you can tell exactly which area is the potential leakage spot. Get a fine spray tube on the can if you haven't already.

[schmdty420]

Well when I took the diaphragms out, they each had been pinched on one edge buy the cap. Guess whoever put them in last time did a sloppy job. So I removed the cap and reseated them. But there is only a small tear on the very outer edge, not on the diaphragm walls. It's torn like a 1/16 of an inch on that lip. Would that be causing that much of a problem? Didn't seem to affect it before I noticed they were pinched. New diaphragms are out of the question for me. I'll just sell this one and save for a newer model.

[alex.s]

valves in the video sound too loose.
problem sounds like either a vacuum leak or a messed up connection to one of the coils.
the diaphram crack could be causing some really weird issues. it almost sounds like the slide is actually getting stuck which might be related to the diaphram pinching/tear issue. it depends which side of the carb the missing screw is. it might cause it to leak gas, it might cause it to leak air. definitely get the screw replaced before continuing.

[davenay67]

Originally Posted by schmdty420

Well when I took the diaphragms out, they each had been pinched on one edge buy the cap. Guess whoever put them in last time did a sloppy job. So I removed the cap and reseated them. But there is only a small tear on the very outer edge, not on the diaphragm walls. It's torn like a 1/16 of an inch on that lip. Would that be causing that much of a problem? Didn't seem to affect it before I noticed they were pinched. New diaphragms are out of the question for me. I'll just sell this one and save for a newer model.

I read another post either on this forum or on Ninja 250 Rider's Club about a guy who repaired a torn diaphragm with a bicycle inner tube repair kit. I think he simply used the glue to seal the diaphragm back together again. YOu might even be able to use a relly thn piece of rubber (such as that used in surgical gloves....cleaned up completely of course) as a backer for the hole/tear repair..??

A repair is worth a shot before dumping the bike, especially as a poor-running bike will not get you good money on a sale.

[schmdty420]

Final Update: The bike is running fairly good now!! Adjust the idle/air mixture screws and synced the carbs. Reseated the diaphragms, again, and cleaned the slides really good. Cleaned jets again and reassembled. Had to choke it to start first time, and has been running great all day. Took it do a 1 hour ride had to adjust the side a few times, as it seemed to be rising every time I stopped. Finally got to sit and idle at 1.2-1.5k. Throttle is pretty responsive, not as snappy as I'd like, but it doesn't want to die when I hit the throttle. Still think its running a little lean, but not too bad. Just wanted to say thanks for everyone's input, it helped a lot.
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[TLYNN]

just a tip for keeping fuel to it with out the tank is to use the small plastic tanks from a snowblower or lawn mower, the hose fits right on and you can zip tie it to the frame