Hi All,

I consistently have a problem with starting my XT250 after I let it sit for 2+ weeks. Prior to storing it for a few weeks, I'll run the fuel out of the carb by turning the petcock to "off" until it dies out.

Here is where my problem comes in..Trying to start the bike after 2+ weeks of storage. If I turn the petcock to "full", and try to start - I could run the starter motor all day and it won't start. If I turn to "Reserve" it fires up first crank. I can instantly turn it back to "full" and the bike won't die out and runs normal.

Anybody have any Idea why this would be happening? I thought maybe bad fuel was still in the lines but I have no idea. Still happens when gas is treated.

I don't know much about the carbed XT250 (what year is it?)

But, the problem probably is among these things:

Venting to the Gas Tank
Something not right about the gasket within the petcock

Are you trying to start with little or no throttle opening? (the correct way)
Have you done the 3-turn mod? (helps starting but won't address the problem specifically)


Alexd

Is the 250 gravity fed? If so, Disconnect the fuel line and open the petcock to both positions. Fuel should run out the same way in both positions, and it comes out fast, have a container of some sort to catch it. If not, are you sure there's enough fuel in the tank with the bike on the side stand?

Is there a vacuum line going to the petcock?

That's an interesting issue.. Have you tried just switching it to Reserve then back to Main before actually trying to start the bike? I'm wondering if what you're really doing is relieving some sort of vacuum in the fuel line. No idea why that would be but it might help to eliminate other possibilities.

I always try to start the bike with little to no throttle. Will give it some if it begins to die out, but yeah it is an interesting problem that I have. I keep the tank full when storing so there is plenty of gas in there. I've never tried switching the petcock to reserve and then back to full to try to relieve a vacuum or something like that.

I can live with this problem - as long as the bike starts and runs fine I don't have an issue with dealing with whatever is causing this. I will keep playing around with it, but may just need to end up starting on reserve for now on.

I'm thinking this too...

Wonder if it's a tank venting issue? If you fill the tank full to the top, the vent (in the gas cap) can sometimes be blocked by the liquid gas so pressure/vacuum can build in the tank.

What's the ambient temp where you park the bike?

Next time, before you do anything else, open the gas cap and listen carefully for a whoosh of air either in or out. I'm not entirely sure why "reserve" would work an "on" doesn't in that case, but it's a start.

The bike lives in a 50 degree (F) basement during the winter time. The closest gas station is a 15-20 minute ride so I don't believe that the tank is full enough for the gas to prevent air from escaping.

Very interesting theories though that I did not think of. Next time I am where the bike lives, i'll try opening the tank first to hear for any pressure release. I'm also interested in trying what Beaker suggested, switching the petcock to reserve and then to on. Haven't tried that combination yet.

Hi Skykine:

I think this problem is caused by air in the line. If you drain the float-bowl and let the bike sit, eventually the remaining gas in the line will drain to the float-bowl and the line is full of air. The air in the gas line has to be pushed out much like air has to be removed when you start a syphon hose.

The normal gas position uses a standpipe in the tank so there isn't as much vertical "head" of gas to make pressure, but when you switch to "prime" the gas feeds from the bottom of the tank and the pressure is high enough to push the air out of the line.

As soon as there is no air in the line, gas will flow freely in either position much like a syphon requires the air to be removed from the line to start.

^ that's a distinct possibility too. Unless it sits for months at a time, running the bowl dry really isn't necessary. Running it for a minute or two with the petcock closed should suffice and might eliminate the problem. That's assuming you're using 100% gas.

If the fuel line is empty and the fuel won't flow in the "on" position, disconnect the line at the carb and see if it flows.