ok 05 yz250 start issues.

[YAMAHA-MATT]

ok i think there might be a little user error. keep in mind this is my frist 2 stroke i am a big bore 4 stroke guy for the most part but i could not pass this deal. ok i took this bike in on trade at my dealership. picked it up for 2k not bad for a bike that only has 10 hours on it and has the little nubbies on stock tires. LOL (working at a dealership has big advantages)

ok so it ran great the day i took it in on trade. i rode it for about 15 mins around my shop. seemed to run fine. the i took it home and ran it for about 1 hour then. then i mixed up some fuel yamaha lube 2R. i mixed a 40:1 mix put it in and ran it for about 10 mins. then i went inside. came out and went to start it up and it ran for about 10 sec then it flooded out. then i went to start it the next day and it did the same thing. after a lot of kicking and adgusting the choke. i pushed it to the top of a big hill and bump started it to do this i got it running crappy as i was going down the road. then i turned the choke off and it took a second to clean out and boom it ran great and ran great all night last night. i wonder if i should try to start with out the choke before i try with it. i think i am flooding it out. or maby i am running to rich of a mix. and thoughts:bonk:

oh i also never turn off the fuel when i get done i think i should start that now as well. let me know if that would cause this flooding out issue.

[Sick Of It All]

get rid of the yama lube.. nothing but crap.. i would foul plugs left and right with that stuff.. if its cold out yeah.. use choke.. get bellray mix or somthing else..

[YAMAHA-MATT]

thats just it. the bike was cold and it wat 29 degs. so one would think that the choke would be needed

[yathump]

The Yamalube is fine, you need to find out what jetting you have then look into how fresh the topend/reeds etc. are

[RCannon]

I dont foul plugs with Yamalube and neither does anyone who jets their bike properly...oil is oil. Jetting is your variable here.

You bought a used bike. No idea what the previous owner put in for jets. Find out and jet it correctly. Your plug issue will go away even if your using Wal mart oil..which many do.

[YAMAHA-MATT]

i have used the yamalube for years in everything else. i know it has new preformance reeds. but i have no idea what size jets are in there. but i think he has it set up to run much leaner than i ham. lika a 50:1 if not more

[YAMAHA-MATT]

I dont foul plugs with Yamalube and neither does anyone who jets their bike properly...oil is oil. Jetting is your variable here.

You bought a used bike. No idea what the previous owner put in for jets. Find out and jet it correctly. Your plug issue will go away even if your using Wal mart oil..which many do.

i am not haveing a plug issue

[RCannon]

i am not haveing a plug issue

I just noticed that.Please dont make me read everything without contact lenses...LOL You having a flooding issue, right?

That would have nothing to do with the oil. You probably need to replace the needle and seat in your carb if fuel is leaking through.

If thats not happening, check the jetting anyway. Running 40:1 in a bike jetted 50:1 will cause it to run lean...not rich. I know, that sounds wrong, but its true.

[locomike]

thats just it. the bike was cold and it wat 29 degs. so one would think that the choke would be needed

At that temp, starting without the choke is a key sign that the pilot jet is way too large. My guess is that all the issues are jetting related. Check your jet sizes and start from there.

When I bought my TM300, it would start without the choke with frost on it. After I went down two sizes on the pilot, I suddenly needed the choke...?

[YAMAHA-MATT]

ok so i talked to the guy who traded it in to the dealership. i just assumed that a guy that would put a full pro circut exhaust and preformance reeds would of put on the proper jets. well he didnt he said they were stock. well shit! so my question is what exactly do i need. we have a lot of random jets laying around the shop. if i can save some cash and not buy the whole jet kit. so my question is exactly what do i need. and in what sizes

[locomike]

Pro Circuit recommends a 175 main and a 48 pilot for a 2005 with a full PC system, on their website. That would be a good place to start. Good luck, and let us know how it is working out...

Also, read the jetting sticky at the top of the forum. It is a great resource.

[YAMAHA-MATT]

thanks bud. i will check that out.

[RCannon]

ok so i talked to the guy who traded it in to the dealership. i just assumed that a guy that would put a full pro circut exhaust and preformance reeds would of put on the proper jets. well he didnt he said they were stock. well shit! so my question is what exactly do i need. we have a lot of random jets laying around the shop. if i can save some cash and not buy the whole jet kit. so my question is exactly what do i need. and in what sizes

Most common mod is to add a pipe and never change a jet. Then live with a bike that runs worse than if you never did a thing to it.Jetting scares people.....Pipes dont.

You dont need a kit. You need 2-3 mains and maybe a pilot jet ...try a 48. Total cost is abotu 20 for all.

What is your elevation and tempere where your riding at?

[YAMAHA-MATT]

no idea of elivation. as we dont talk about that in flat ass iowa. LOL

i ride year round so for instance when i ride today it will be 55 deg

[RCannon]

Google says the lowest point is 480 ft, the highest is slightly over 600. No problems there with running the pc jetting.

I would get a 175 main, 172.5 main and a 48 pilot and test it out. Set your needle back to the stock position or possibly 1 step leaner. You might want the 172.5 in the summer.

[shrubitup]

Google says the lowest point is 480 ft, the highest is slightly over 600. No problems there with running the pc jetting.

I would get a 175 main, 172.5 main and a 48 pilot and test it out. Set your needle back to the stock position or possibly 1 step leaner. You might want the 172.5 in the summer.

What he said. Know that the aftermarket reeds also make it run that much richer. Once you get the jetting leaned out, try it with 32:1 mix too but 40:1 ought-a work too. 50:1 gives you more gas, lower engine temps, and likely a spooge issue which you haven't asked about - yet.

[YAMAHA-MATT]

i am going to be getting this think fixed next week. but i still wanted to run it this weekend. it had run great friday night then i drove out to the trails and kicked it over and it started ran for bout 5 seconds then blah nothing. kicked and kicked but nothing. i could of lit this thing on fire i kicked till i was blue in the face. i think i have offically fouled the plug. so i am going to take that apart this morning and try to clean the plug. if not i am just screwed for the weekend. i was so pissed yeasterday. gerrrrrrrrrrrrrrrrrrrrrrrrrr

[jeffdelio]

A fouled plug is a fouled plug, put a new one in it!!? Do you know what jets are installed yet?? Air screw setting? Air filter clean? I agree with RCannon, 175 or 172 main, 48 pilot, air screw 1 to 1.5 turns out, needle clip position #2 or place a shim in it for a 1.5. Put a new plug in it, clean the airfilter. I would dis-assyemble the carb and clean it out as well. Check float height, etc. If the top end is sound, the bike should fire up every time and run like a champ with the proper jetting, pre-mix and routine maintenance. Do you have the service manual? Very good info about Carb tunning! I just purchased a 05 YZ 250 about a month ago and went through the same scenario as you. I ride at 6-10,000 feet so my jetting is alot leaner than you but the thought process is the same. My bike had a 172 main, 50 pilot and air screw about 1 turn out, fouled plug just like yours. Installed 162 main, 45 pilot, air screw 2turns out, new plug, cleaned carb, etc. The bike hauls ass now:ride: Perform plug check, brownish tan= good A/F ratio. IMO the pilot jet and air screw are what make starting the bike a piece of cake or a royal pain in the ass. Get those two things dialed in, then set your main jet and needle. Check out the graph to get a feel for what setting part (jets, needle, clip position, air screw) effects what area of the powerband (throttle position)

[YAMAHA-MATT]

thanks for the info. i put a new plug in and it starts first kick every time. the bike has stock jets in it now. so i will be putting new ones in this week.

thanks

matt

[rooster78910]

Sorry to jack the thread, but I was talking to the mechanic at my local shop, and he said that new spark plugs have some kind of coating over the porcelin(sp), and when you clean a plug it takes the coating off and the plug doest last near as long as a new one, any truth to that?