bogging down, help please

[FlamingYellowInsanity]

So here's how it went down.

I was on my way to school this morning, in the carpool lane doing about 70mph when I noticed my rpm's were a little high for the speed I was going. I didn't think much of it, because I was heading into a 30+ mph headwind. Anyway, a few miles later, and about 25 miles into my ride, the engine just totally bogged down, like I had run/was running out of gas. But I wasn't! I had a half a tank still!!!

Now, I am left with a bike that runs fine, revs fine, even runs good on the stand. But any time I try to run it on the street (i.e. under load) its will be fine to about 20 mph, then just bog down. I still accelerates, but about as hard as a 50cc scooter, though I can still reach higher speeds like in the 60+mph range.

Any ideas? The only things I've done to the bike is a 15 tooth front sprocket about 3 weeks ago (other than maintenance). I'm thinking of just taking it to a mechanic, but I want to see if it might be an easy fix first.

So in summary the symptoms are:
-bogging at speed
-runs fine unless under load

Any help would be greatly appreciated!

Travis

[sometimesido]

I have no clue, but have you checked here?

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

[FlamingYellowInsanity]

Yeah, I checked there first, there wasn't anything on there that was even remotely similar to my problem. Thanks anyway though!

Travis

[TnNinjaGirl]

I'm pretty sure that's what Jimi's (KnoxNinja) bike is doing too. I don't think he resolved it yet.

Perhaps the petcock has gone bad...?

[FlamingYellowInsanity]

It could be the petcock, but it's not very high on my suspect list right now. I'll probably be taking it to a small local mechanic in a few minutes for a diagnosis and possibly/probably to fix it. I can work on my scooter, but I need the bike to badly to be able to tinker with it for a few days. the cage is barely running also, and the scooter just got a rebuild. Seriously, 3 vehicles and none are running good, lol!

Travis

[sometimesido]

Originally Posted by FlamingYellowInsanity

So in summary the symptoms are:
-bogging at speed
-runs fine unless under load


Travis

doesn't this mean you're not getting fuel at higher rpm?
just a thought.

my vw did this because fuel pump was going out.

[ajaygraci]

hmmm hoe dopesnt happen to me

[kkim]

Travis, try filling the tank with gas and see if the problem goes away.

[JCCJMM_]

Do you have an aftermarket fuel filter in-line after petcock??

[Nemy]

What have you troubleshooted so far? Switched to prime/reserve, check air intake/filter etc.?

[FlamingYellowInsanity]

Did switch to reserve, still had half a tank of fuel, so I know there's fuel in it. The bike was bought used (with only a few hundred miles), so I'm not sure if there's an aftermarket filter in line. I decided that I need it to badly for school and took it to a reputable shop a few miles from my house to diagnos it, then we'll see if they fix it or if I do depending on what it costs.

Another thought that I just picked up from my scooter forum is that possibly one of the main jets fell out. Someone I know was having a problem almost identical to mine, well in scooter form, and his main jet fell out. It does sound fuel related one way or the other... g'night.

Travis

[capt_bugaloo]

If you've ruled out bad fuel, then I suspect you have some kind of debris partially clogging a jet in your carbs.

[FlamingYellowInsanity]

seems that the shop thinks it was stuff clogging the cali emissions system, not letting air back into the fuel tank creating a vacuum lock type situation, in addition to getting junk such as carbon from the emissions canister into the carbs and clogging them up somewhat. Should be a couple hundred in labor to fix and then good to go.

Travis