Gz250 problem

[Lovewuno]

Hello, I’ve been in the shadows of this site for months but this is my first post! So I’ve been trying to get this 2007 gz250 I found on Facebook running (good) and just can’t seem to get it working right. So the story behind the bike is it hadn’t run for about 10 years (last inspection was 2014). So for starters to get her working I cleaned out the tank with the vinegar method. Had to rebuild the petcock vacuum with a kit, and clean/rebuild the carburetor with another kit. After getting that done I changed the spark plug, charged the battery up, put on an inline fuel filter and she started up. So I could ride it around the neighborhood for about a week whilst troubleshooting still (could get up to second gear no problems) but had to ride with half choke, which is the start of my reason for posting here today. So it starts and idles good but when I toggle the choke off(all the way away from me) it idles way too high and when the choke is on (lever towards me) it will die. So when I was gonna try and take it out yesterday it cranked over same as usual but when I put it into gear and started trying to accelerate it didn’t have any power behind it and would back fire. It got me down the street and I had to walk it back to my house. Also forgot to mention I got a new air filter for it and changed the oil/new oil filter. Just wondering if anyone could help me figure this out. I sprayed starter fluid around the carb boots to see if there was a vacuum leak but it had no effect on the idle of the engine. Also tried fooling with the pilot screw and the throttle stop screw. It might help to mention I took the carb off again today and it seemed like my pilot jet was backed up a bit so I sprayed it out with carb cleaner and when I slapped everything back together I could get it to drive a little bit but still lacking power and backfired on me. Any help would be greatly appreciated if anyone has a clue

[Lovewuno]

So I ended up fixing it after tons of trial and error and taking the carb and tank off about 40 times ��. Figured I’d write about it here in case anyone runs into the same difficulty I did. So the reason the bikes choke was all messed up is because the jet I had installed as the starter jet was way to big (the rebuild kit only sent the main jet and I was too eager ripping the carburetor apart plus the jet was solidly filled with gunk so I couldnt see how small the hole actually was). So after I figured that out I found out a way to clean all the gunk out of the original jet after trying everything, and the thing that ended up working was holding a lighter up to it and then blasted carb cleaner through it while it was still hot and it blew the mess right out. So I hooked everything back up and then the choke issue was fixed so I got my hopes up and she still didnt run right. That’s when my fouled spark plugs came into play (covered in carbon deposits from running so rich with the wrong starter jet in place) and it was causing a backfire to come out through the carbs which freaked me out so I kill switched it and got back to researching. That’s when I found out the plug misfiring can cause that so I just hit it with a soft wire brush and it fixed that problem, yet the bike still was not running right! Now the problem was that my bike idled really good no more backfires and the choke was working how it was designed but it was too lean now and the bike would die if I pulled the throttle more than 1/4 open. So apparently that’s because the collar for the needle found inside the main jet circuit (not sure if that’s what it’s called, also saw someone else call it the needle jet) was mistakenly put back in place the opposite direction. The beveled end is supposed to face the needle. So I flipped it now everything’s working how’s it should!! Moral of the story is I was too eager and inexperienced so i fluffed some stuff up and made it way harder on myself but hey that’s how you learn and hopefully, I can help someone else out too who has ran into my multitude of problems. Cheers

[Vegas Street Rider]

Fixing mistakes made when working on these bikes are lessons remembered. Thanks for the detailed account. Glad you have it up and running like it should.