Help Needed ... Fuel Problem??? - Kawasaki Ninja 250R Forum
 
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post #1 of 7 (permalink) Old 03-21-2014, 02:42 AM Thread Starter
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Help Needed ... Fuel Problem???

Hello all, Jecks here, and i am currently in need of some assistance which i am hoping to receive from here.

i own a 2008 ninja 250 and have owned it for about 5 months now, for the first 2 months i had it no problems i mean its the first bike i have ridden and it was plenty powerful enough for me while im learning but 2 months in i was starting to go faster (it has a top speed of 150km/h and thats with the help of a hill) and i was mainly testing it out because i was planning to ride 2000km form SE QLD Australia to VIC in the south of Australia so i wanted to know that it would make it fine. the bike past the test fine i had done several 3 hour long rides on it and not a problem but 400km into the journey south and bam bam barr at 110km/h it just starts spluttering and coughing so i slow down to 80 and it starts running fine again... long story short the bike has an intermittent problem that when it feels like it, it just wont rev above 7k rpm and seem to only run on one cylinder

now when this first happened i was quite worried but i know it was not mechanical and to me (first year apprentice) it sounded electrical like i had lost spark and my number plate gave my theory so proof as it was BLACK from the exhaust so my journey to melbourn VIC while slow still fun (i was not turning back) so i made it and it just so happened that i was staying with a fellow bike enthusiast who help me change the spark plugs and give the bike a nice service

after this was done it seemed to be fine it didnt fault until the bloody day i was leaving (of course) so i took it to a dealership and asked the mechanic there what he thought it was and he came to the same conclusion COILS unfortunately he did not have the equipment to test them and i did not feel like paying for it either so i got it home and ordered some second hand coils for the bike and have just installed them and took it out for 2 hours and thought that it fixed it but about 10 minutes away form home it dose it again reducing me to a top speed of about 90-95km/h

the strange thing is just how intermittent this problem is because just as i reached my drive way (which is 1km long, i live in the middle of no where) and the problem was gone and the bike rode fine for the little bit to home

ANY help or suggestion and welcome the next thing i could think of is maybe for some god only knows reason every now and then the carbs stop giving the engine enough fuel to rev higher but that wouldn't explain why soo much unburnt fuel comes out the exhaust
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post #2 of 7 (permalink) Old 03-21-2014, 06:41 AM
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Coils rarely go bad, but when they do it's pretty crappy performance. Are there any other modifications to the bike?

If not, I'd look at a couple of things. Since you've changed the plugs already, that's one thing you can rule out.

Check your air filter and snorkel to make sure they are clean and free of obstruction. Improper air fuel mixture will cause the bike to run rich.

Ensure that the gas cap is venting properly. A cap that does not vent properly can cause improper fuel flow, especially when the engine and ambient temps are high. Carb bowls don't fill up properly therefore you get some fuel starvation, even to the point of a shutdown in some cases.

Make sure the fuel level in the tank is adequate. Low fuel levels also will cause fuel to flow slower as the system is gravity feed.

There is a problem with some IC Ignitors (CDI), although there is no recall or service bulletin on it. The problem seems to mainly occur when the temps are high outside. This may cause the rpms to read higher than they should but the speed doesn't necessarily change.

If you've got unburnt fuel coming out of the exhaust, you may have a compression issue or a timing problem.

You can also use the Troubleshooting Guide to help narrow down any other problems you may happen to notice.
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post #3 of 7 (permalink) Old 03-21-2014, 05:17 PM Thread Starter
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thanks for the reply
-there are no modifications to the bike that i know of
-also already checked air filter and snorkel
- now with the gas cap thing how do i know if its 'venting' never heard of this before and would like to test
- and yes the tanks has been emptied and cleaned twice i know its got nothing to do with lack of fuel in the tank
- i doubt its your next suggestion as there is a performance drop
- and as for timing or compression this is also doubtful as it is an intermittent problem sometimes it runs fine and others times its just like nope
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post #4 of 7 (permalink) Old 03-21-2014, 06:18 PM
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Quote:
Originally Posted by DeJackal View Post
.... now with the gas cap thing how do i know if its 'venting' never heard of this before and would like to test
That's easy. Does your gas cap make a whining or whistling noise when it is hot outside or when the tank is full of gas? If not, chances are it not venting properly.

Also when you cleaned the tank, did you inspect or clean the inline fuel filter on the carb?

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post #5 of 7 (permalink) Old 03-21-2014, 06:38 PM Thread Starter
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no i have not heard it venting then so this could be the solution

as for the filter ON the carbs i dont remember but i know the guy that was helping me said the fuel filter was fine i didnt check it myself

as for the venting thing i just pulled it apart but the manual says not to blow into the vents so how do i clean them do i have to pull the tank off? also im about to take it out to test the vacuum in the tank just by making it fault and then opening the tank to see if it starts running better this should be a pretty easy way of finding out if this is or is not the problem
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post #6 of 7 (permalink) Old 03-21-2014, 07:52 PM Thread Starter
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i am currently uploading a video because it has completely changed what was happening
https://www.youtube.com/watch?v=GXck...ature=youtu.be
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post #7 of 7 (permalink) Old 03-21-2014, 08:59 PM
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I took my gas cap off and completely disassembled it. Inside, around the too small one-way diaphragms were white crystals where gas vapors had dried. Every piece of rubber was cleaned and the key tumbler re-lubed, then re-assembled. I also did the gas cap mod and made a few of the vent holes a tad bit bigger. It does it necessarily get rid of the noise, but I have not had a problem since. Most times cracking the gas cap fixes the fuel flow problem.

You said you had no mods to the bike, but you do have a Yoshi slip-on exhaust. With a slip on exhaust it is recommended that you at least shim the needles. If the previous owner put larger jets in the carbs, it may be running a bit rich. Fire out of the exhaust is common especially if there is no baffle in the can and you're trying to hit the rev limiter. When was the last time you had the valves adjusted?

Last edited by DaBlue1; 03-22-2014 at 05:22 AM.
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