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2006 Wr250f performance

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Ok so I have a wr with the gray wire cut. The exhaust has the rear packing stuff out and the air box had been cut but has duct tape over. I got it that way. I removed the duct tape on the air box and it ran like shit so I put it back on. Question is that I want to get the lexx exhaus, open the airbox and then rejet? Would this be considerably different than the power the bike is putting out now? Again the air box is closed and the stock muffler is on with the rear packing out. I got the bike this way. I want to know if that lexx exhaust with stock header with air box opened and rejetted would be the nice power I am looking for?

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Check the jetting database:

http://www.thumpertalk.com/topic/258279-jetting-d-base-for-yzwr-250f/

look for similar bikes and altitude.

Generally speaking, mods to the airbox and exhaust will lean it out to the point it doesn't run properly.

You will see most of the posts showing 175-180 main jet and 40-42 pilot jet with fuel screw running between 1.75-2.75 turns out. The best jet kit is the JD, but you can use the Dynojet. I've used both and prefer the JD over the Dyno prob 10-1. The key is that the accelerator pump is working properly, so pay special attention to yours and verify operation. I'm doing leak jetting now on 2 of mine, and yes it makes a huge diff. GOOD LUCK.

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Yeah I will jet but I'm wondering if I open the air box and jet with the stock exhaust ( with the outer baffle out) will the results be about the same or way different compares to the lexx exhaust and open the air box and rejet? About to buy the lexx exhaust but wondering if it will be worth it for me.

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I go for value, not bling. So I get stock YZ pipe/muffler off ebay and add sparky, works just as well. And yes, the stock WR muffler is a different design and IMHO does not perform like a straight thru system. When I removed the stock system and jetted my '04 WR, the bog went away, same with 05 when I fixed the leak jet so it would squirt properly.

I've never owned the Lexx system but seems like it should work.

Edited by ronbuell

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Ok good pictures. Ordering exhaust now. Now what jets kit would I buy if the air box will be opened and the lexx exhaust and the throttle stop screw cut? Don't know what to order. I know jd but they have different stages. Thanks for the help!

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I've used the Dyno Jet kit and wouldn't do it again.  It worked well but they use their own main jets with an adapter and the numbers are different than Keihin jets.  


With the aftermarket pipes you will have to repack them.  I do it every season, at least.  I find that they sound good new but slowly get louder until I realize that the bike is too loud.  You don't have to replace it, just pull it out, stir it up and put it back in.   Sometimes add a little where it's cooked.  No experience with Lexx, just FMF and others on street bikes.  


I got tired of the noise and repacks on my wr250f.   Took out the core and packing out of the FMF Q4 and welded in a stock baffle from a wr450f.  Here's a couple pictures of what FMF has inside, this one's about 4 years old, the newer ones are a little different.  I suspect the other brands are similar.   


baffle1.JPG


baffle2.JPG


I put a couple hose clamps around the ends of the mesh on the outside of the core, that comes loose and makes it louder.  


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Ok got all that info. I am reading a lot of stuff about leak jets? While I'm in there thinking if I should change the leak jet? Do the kits come with leak jets?

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This is all new to me and going to be a huge learning experience but I'm sure I will be ok. May take some extra time but I'll get it

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JD Jetting provides a #60 leak jet, compared to the stocker, which I think is 90 or 95. I put one in, and it made a big difference, reducing the tendency to bog. I had a little bog, especially when warming up, but the leak jet just made the bottom end feel better.

 

You can find the leak jet part numbers on this website, or on thumperfaq.com.

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