Need ideas for a non-running bike

[aharnak]

Hey all,

I've got a frustrating issue with my bike that has prevented me from riding for a few weeks now, mainly because I haven't had the time to fix it.

It seems like it all started when I put a new fuel filter on it a month or two ago. It was running perfectly, but I needed to replace the fuel lines with newer ones because the old ones were dry rotting. I figured I'd put on a fuel filter for good measure. Unfortunately the first one I used was a bit too big, and I had to bend the line awkwardly to make it fit. It ran fine for a while, and then began to lose power randomly after being warmed up and stall, more and more frequently until it was unrideable.

A member on the forum suggested that I drain the carb bowls and run some Seafoam through the system, which I did. I also swapped out the fuel filter for a smaller one that fit properly. And viola! The bike worked for a few weeks perfectly.

But the problem eventually came back - I always noticed a bit of surging on the highway, especially going downhill, but it got worse. Then it started to become more difficult to start (wouldn't rev up past 2k even with full choke for several minutes with hard knocking sound). Throttle response became worse and worse, with the engine bogging and trying to stall any time I gave it any gas. Playing with the choke would help get it started and running again after it stalled, only to stall again 500 feet down the road. I eventually towed it back to my apartment and covered it, and haven't touched it for a few weeks.

So here's what I've done to troubleshoot this problem already:

- Replaced the spark plugs despite the fact that they're relatively new. I gapped them properly. The old ones didn't show significant signs of richness or leanness to my untrained eye. Maybe they were a little darker than they're supposed to be, but nothing crazy.

- Drained the carb bowls again

- Removed the fuel filter entirely and tried running with just a straight fuel line. I also checked the flow by applying vacuum to the vacuum line, fuel flowed out relatively easily (although I'm not sure how quickly it's supposed to come out).

- Removed the air filter and opened the air box to see if there was a restriction. There wasn't.

So my question is this - what the heck should I check next? I'm getting frustrated - I've had a lot of issues with this bike and it's relatively new (2007 with 8k miles), totally stock, and well maintained. I'm tempted to take it to the dealership but I just can't justify the expense at the moment, which means if I can't get it running I won't have a bike for another three or four weeks. Any advice would be greatly appreciated.

[GeorgeRYoung]

There's a vent in the gas cap that is supposed to let air in as gas is consumed.

If it's clogged, you'll lose power and may come to a stop.

Easy enough to check, run with the gas cap cracked open.

[jkv45]

My guess is the problem is one of two things - fuel or carbs.

I'd completely drain the fuel by removing the tank and dumping it into a clean pan. See how it looks. Is there water or rust?

Fill the tank with fresh 87 octane. Ethanol-free gas is always best if you can get it. Drain the float bowls again. You'll need to set the petcock to prime or apply vacuum to it to let the new fuel flow - or you'll need to crank a bit to build vacuum.

Put the battery on a charger and make sure it's fully charged before trying to get it going.

If that doesn't cure the problem most likely you'll need to pull the carbs and clean them. Do some research and follow the cleaning procedures carefully or you'll need to do it all again. Basically, the small orifices in the pilot and main jet (and the jet holder) get plugged easily and need to be carefully cleaned with a small copper wire while spraying with carb cleaner. High pressure air is handy to have to blow out all the passages after spraying/soaking in carb cleaner.

Also remove the idle mixture caps and needles when you have the carbs off. Set them to about 2 turns out for starters. You'll want to be able to fine-tune them when you have the carbs back on.

[Motofool]

Originally Posted by aharnak

.........I also checked the flow by applying vacuum to the vacuum line, fuel flowed out relatively easily (although I'm not sure how quickly it's supposed to come out).....

Frustration won't fix your bike, check these:

http://faq.ninja250.org/wiki/Troubleshooting

http://faq.ninja250.org/wiki/Intake

It should flow about 2 cc per second.
Drain it into a glass container for a while to verify the vent suggestion above.

There are internal mesh filters inside the tank (part of the petcock) and inside the nipple of the carbs, where the hose connects to.

[aharnak]

I sincerely appreciate all of the responses. While I was disassembling to look at the carbs, I noticed that neither of the two boots between the carbs and the engine were seated properly. Hence, I found a major vacuum leak! This is probably the cause of every intermittent problem the motorcycle has had since I've owned it. I reseated the boots, did the battery box mod while I was there, and sprayed some carb cleaner into the visible areas of the carbs. I also ran a good bit of seafoam through the system. I can safely say that it's running perfectly now. I went on a nice long test ride (first one in a month!) yesterday and fired it up again this morning. It's running well, and it starts easily. Thanks again guys

[jkv45]

Glad to hear you got it sorted and it was an easy fix.

Interesting that it was a vacuum leak. Typically a minor vacuum leak gives you high idle, surging, and a hanging of RPM after closing the throttle. Sounds like this was more significant of a leak.

Thanks for giving us the update.