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YZ250 New member with new to me 05 YZ250

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Good afternoon everyone,

This is my first post (sorry for it being a little long winded) and I look forward to learning the ins and outs of the YZ 250 from the years of experience here! I grew up racing 80's and 125's in southern Michigan and have been away from the two stroke lifestyle for longer than I would like to admit. I recently took my daughter to the Daytona Supercross this year and she fell in love with dirt bikes.  So trying to get her more interested in the sport, I just picked up a new to me 2005 YZ250 and 2007 KLX110 for her. The KLX110 is a solid bike for her to learn on and can't wait to get her some seat time. I do have a couple of questions concerning my YZ250 though. I bought the bike with some knowledge of the history of it. The motor itself is stock and has 5hrs on it from the last top end rebuild has great compression and starts 1st or 2nd kick. Crank seals look good and no noticeable air leaks with a soapy water test. The only mods to the bike are FMF fatty pipe(seen better days), FMF TC2 silencer, v-force 3 reeds (reeds seat great) and it has the UFO restyle kit. The bike came from Colorado and is jetted for the Colorado elevation according to the previous owner. As it sits right now it produces a lot of smoke and spooge at idle and while riding (1/4-1/2 throttle) to the point of it dripping down on the swingarm after a quick trip around the block which I kind of expected considering the Colorado jetting. I will admit that I have not opened it up all the way through the gears yet due to living in a subdivision and wanting to re-jet it prior to taking it for a real spin . However, upon tear down of the carb I found that it had a 170 main jet, a 48 pilot along with the N3EW needle on the second clip, the airscrew was a crazy 4 1/2 turns out. Spark plug was very black and wet. I have been researching jetting specs for an at sea level condition (live in Jacksonville, Florida) but most of the recommendations are using the stock N3EJ needle. The MXA article states to run a 178/50 combo with the N3EW needle on the 4th clip, but they do not state what elevation that recommendation is for and it seems like it would be very rich for my current riding environment. I have searched through and read the entire jetting thread and read a lot of different combos to the point of being overwhelmed. I also read the thread about swapping to a #40 power jet, but I figured I should get the jetting in the ball park first before I go messing with the power jet. Can anyone suggest a good safe starting point for jetting with the N3EW needle? I was thinking of a 175/48 on the 2nd or 3rd clip. Thoughts? I have an assortment of jets ranging from 155-178 mains and 32-55 pilots. I am currently running a 50/50 mix of 93 pump gas and C-12 mixed at 32:1 with Castor 927.  I also plan on repacking the silencer this weekend to get that fresh and get rid of any past build up along with putting a fresh spark plug in it and checking the current timing. Any inputs or starting point would be greatly appreciated!

Justin

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I can't comment on the needle but 170 is great for Colorado but at sea level it should be very lean on the main

My son has a 05 and runs stock jetting 178 main, 50 pilot could probably use 48 pilot, 3rd clip on needle and 2 turns out on air screw.

I would definitely start with packing and though 927 is super oil my understanding is unless your on the pipe often you will spooge alot

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Thanks for the inputs on the oil. I was not aware that it maybe making the spooge worse I just remember using it when I was younger and racing so I went with what I knew. Guess I have more research to do. At this point I am unsure of what the use of this bike will be. Depending on how much my daughter enjoys riding it may see some racing in the future. As for the jetting I put a 178 in it today and left the pilot at 48 and the N3EW needle on the second clip. I will take it out for a run this weekend and see how it responds.

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Just now, rojo_143 said:

Thanks for the inputs on the oil. I was not aware that it maybe making the spooge worse I just remember using it when I was younger and racing so I went with what I knew. Guess I have more research to do. At this point I am unsure of what the use of this bike will be. Depending on how much my daughter enjoys riding it may see some racing in the future. As for the jetting I put a 178 in it today and left the pilot at 48 and the N3EW needle on the second clip. I will take it out for a run this weekend and see how it responds.

Should be good just check spark plug after a little bit, it'll tell yeah how she's running

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UPDATE: So I repacked the exhaust this weekend, it no wonder it was spooging as much as it was there may have been 5 inches of packing all stuffed at the end of the silencer. So I removed all of the old packing cleaned out the canister and repacked. I also swapped out the 170 main that was in the bike for a 178 and left the 48 pilot in there for now. Warmed the bike up then swapped plugs and took it for a quick ride through the woods. The bike runs a lot better and does not smoke like it was nor spooge near as bad. Spark plug looked a little rich but it was quick short ride with only a couple full throttle pulls. At this point it is just leaking out of the rivets that attach the spark arrestor which is acceptable for now. I believe once I run it some more and clear that out it will stop for the most part. Overall the bike rips and is a blast to ride. Throttle response is crisp with little to no bog. Next trip will be to the track to work on suspension adjustments and other fine tuning. @Smoking 2's thanks for the help! 

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Glad you got the bike sorted out better.  FYI MXA is sea level with their jetting specs and 32:1 oil ratio. 

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