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Yz250 wont start

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Hello all! I have a 1995 yz250 that i took out riding for the day last weekend. This bike was owned by my bestfriend, and a few years ago he did a top end on it. He only put about 8 hours on the top end. Unfortunately, my friend passed away a couple of months ago. His family wanted me to have his bike. This bike has started right up 2nd kick everytime. When i first started riding, the bike was running great. After a couple of hours i pulled over to the side and the bike bogged out. I started it back up, but had to turn the choke on to start it. My muffler ended up falling off. So i stopped riding. When we were ready to leave, i slid the muffler back on and carefully rode the bike back to my truck. Once i got back to my truck, the bike bogged out and now i cant get it started at all. I noticed a large gash on the exaust pipe itself. Almost as if it was about to come in half! I checked my spark plug and i have great spark. I also checked the reeds and everything seems good. The bike still had very good compression. 175 psi. Any ideas on why it will not start?

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Check the timing by the position of the stator plate on the mounting screws.

I'd start with a more basic thing, like cleaning the carburetor. Focus on the pilot jet as they are very prone to clogging after the bike has been setting for an extended period of time (sometimes they'll start and run for a while until the sediment and collected gunk get's stirred up from running again). I'd also take the tank off, clean it out thoroughly, and check the petcock filter to make sure it hasn't deteriorated and fallen apart somewhere in the past, allowing anything in the tank a free passage into the carburetor.

Edit: 175 psi is just marginal in a YZ250. 200-210 would be more like what I'd be wanting to see in a good top end.

Edited by OLHILLBILLY

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Change your spark plug and maybe take apart your carb and carb/air clean the jets. My bike had a bad bog and would foul plugs and never have consistent power. After that it was fixed. Hope you figure it out!

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I forgot to mention also, i took the carburetor apart, and the jets apeared to be clean. However, my main jet is a 180. Which i heard is very rich? I believe factory settings for a 95 yz250 is 175 for the main jet. The carb also has gas pouring out of the overflow once i try to start her up. This had not been happening prior to this problem

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I forgot to mention also, i took the carburetor apart, and the jets apeared to be clean. However, my main jet is a 180. Which i heard is very rich? I believe factory settings for a 95 yz250 is 175 for the main jet. The carb also has gas pouring out of the overflow once i try to start her up. This had not been happening prior to this problem

You may have messed up the needle valve or float height level while you were in the carb, if fuel is pouring out. Might be a good idea to find a buddy who has some experience tinkering with carbs to supervise or lend a hand. At that age, it may be wise to replace the needle valve as well, if it hasn't been replaced.

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The bike will never run correctly with a pipe that has a hole in it, you need to replace it before doing anything else. You will be running around in circles.

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I forgot to mention also, i took the carburetor apart, and the jets apeared to be clean. However, my main jet is a 180. Which i heard is very rich? I believe factory settings for a 95 yz250 is 175 for the main jet. The carb also has gas pouring out of the overflow once i try to start her up. This had not been happening prior to this problem

Float needle isn't closing for whatever reason. Either the float height is wrong, the needle is bad, or there is some grit stuck in it that is holding it open. You need to flush and clean the whole fuel system starting with the tank and going all the way through the carb. Jets, especially pilot jets, can "appear" to be clean, but in reality not be. Blow it out with spray carb cleaner until there is a perfectly round hole in it. A 180 main is big, but that's the Euro stock spec for my '03, but no idea on an older model. Also pull the reed block and have a look at their condition. And as others have stated, you're pretty much wasting your time until you get a usable pipe on it. A 4" break in it will make the bike never run right.

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