New owner of '99 gz250. Lots to learn.

[ThisGuysFirstGZ]

Hey, guys I just purchased my first bike and it is a gz250 that runs and rides and brakes and all that. I have never worked on a bike before this. However, I noticed a few minor things that could lead to big things after research and am looking for help. Before I break it down, let me give you a limited history:

Bike was purchased from a guy who did not ride it often and re-worked the wiring himself, along with some minor things like throttle set-up, and some cosmetic things (seat, tail light, took off neutral indicator and turn indicators. It's got 3600 miles on it so it's "young"

Now for the breakdown:

1)The bike starts on "on" fuel position with full choke, but not always. Starts on prime right away.

2)Switch it back to "on" after starting and it will sputter out after riding for aprox 10-15 seconds. Rides on prime to go home (just around the block).

3)Noticed oil level is very full. Checked oil cap and smells like gas. Air filter smells like gas too. (normal I think, but looks like it's wet with gas)

I did a lot of youtubing for the answers and some were addressed, but here I seek the sage knowledge of other gz250 owners for the best solution. Should I have a mechanic look at it? Is this a job that I can do myself? Is it just a matter of replacing the petcock and changing oil? Or do I need to do something bigger like rebuilding the carb? If this is in the wrong thread, please redirect me.

Thanks for your time from a humble new beginner.

[Vegas Street Rider]

Welcome to the forum ThisGuysFirstGZ. It sounds like you need a rebuild kit for your petcock and it is available online on Ebay and multiple other sites. Just reference your make, model, and year of your bike. Although it might not be necessary, I would replace the air filter (about $45) and change the oil and filter. Fill the crankcase with the appropriate 10/40 W oil to just below the full mark with the bike level. That should take care of most of your running issues. Adjust your throttle screw so that the bike idles around 1500 rpm when warmed up. The adjustment screw is located on the right side of the bike under the fuel tank behind the cylinder head. It is white with a knurled round knob.
While you are at it, I would buy some Seafoam and add it to your fuel tank to clean things out. I believe it is one ounce for every gallon of fuel (3.4 oz. on a full tank).
That should get things up and running. There are plenty of how to's on rebuilding the petcock on line and it is pretty simple with just a few basic tools. The whole bike is pretty easy to maintain even for a novice. Download the manual online as well as this will help you see how everything is put together. Good luck and safe riding.

[alantf]

Might not need a petcock rebuild. "run" position works via suction (vacuum) from the engine, so it's possible that it's a leak in the pipe to the petcock.

[Vegas Street Rider]

That's true. Replace the hose to the carb and see if that takes care of it. Seeing as how the fuel is flowing into the carb and getting the air filter soaked when it's in the run position still makes me think it's the petcock unless you let it sit with the petcock in the prime position for some time.

[ThisGuysFirstGZ]

Thanks Vegas, and Alantf

I definitely intend to change oil and filter since it's most likely got gas in it. That goes for the air filter as well. I can't say how long the bike was set on prime since the seller had it on prime when he showed the bike and ran it around the block. I didn't notice to put it back on "on" when I rode it across the city to get to my house. At that point (being a noob) I did not check it when I went inside to snooze. Who knows how long it has been on prime. I know this can be hazardous to my bike and I am hesitant to take it into a shop because I feel like this is my opportunity to learn something critical on my bike.

I had suspicions of a leak somewhere around the petcock or maybe somewhere else. But I will first do those filter replacements and assess the situation with the tubes and go from there. I'm super worried about fucking up my engine because it only has 3600 on it!

[Vegas Street Rider]

Relax. It will work out. My petcock failed and after repairing and replacing said filters and oil change, all ran well. Take your time and don't freak out. We are all here to help.

[ThisGuysFirstGZ]

I changed the air filter and oil/filter. Readjusted the throttle screw so the idle is just right (might be a bit higher, I don't have a tach on it.) I'm hesitant to replace the tube to the petcock. I have a new fuel hose and all, but I don't have a garage and feel like I might spill gas all over the street since I'm so inexperienced.

Anyways it runs a hell of a lot better, but the issue of it not getting enough fuel while riding is still there. I have been intermittently switching it to prime every now and then just to get more fuel into the carbs, then switching it back to on.

[Vegas Street Rider]

With the petcock in the on position, no fuel will come out. You can then change the hose out. I would put a fuel filter inline while you were at it. You can usually find them at most auto parts stores.