XT250 Idle Screw Plug Removal

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XT250 Idle Screw Plug Removal

Postby 4Strokes » Mon May 23, 2016 9:40 am

Topic: 2008 XT250 Idle Screw Plug Removal
Author: lil_mynx
Posted: 11/09/2008 09:58:06 AM

Here is how to remove the factory plug on the 2008 XT250 to gain access to the idle mixture screw without removing the carb from the bike. Here are the tools you'll need for the job.

First you'll need to remove the choke lever and move it aside with a 17mm wrench. Be careful when you put it back on not to over tighten the plastic nut.

Here is your goal. The plug removed.

You'll need a 3/32" HSS drill bit and a bit extender with at least 5" in length.

Drill a hole in the plug being careful not to drill into the mixture screw on the other side. Screw in a screw that is slightly larger then the hole and long enough to grab hold of with your pliers. Gently wiggle while you pull to remove the plug.

Now you can use a #5 screw driver to set your idle mixture screw. With the exhaust mod done the bike runs best at 2 1/2 turns (exactly where Yamaha says). But I found it set at 2 turns from the factory. This my have helped with emissions but caused poor throttle response and longer warm up time.

Reply by jsmiley4002 on 01/28/2009 6:25:40 PM
i just uncorked my exhaust, and it runs and sounds great, i go for this step next, just a few questions first cause im real nervous about getting close to that carb with a drill in hand, how easy of a drill was it? overall was this a difficult step? thanks!

Reply by lil_mynx on 01/29/2009 3:46:08 PM
The plug was soft so don't push too hard. You'll know when you're through so take your time. You'll want to turn the mixture screw in gently so when it seats you don't damage the needle (if you would please count the turns till it seats and post what the mixture screw was set from the factory). Then turn the screw out and counting the turns till you reach 2 1/2. If you have any questions let me know.

Reply by jsmiley4002 on 01/30/2009 01:02:17 AM
gotcha, il give you the heads up once complete, with the exhaust uncorked i feel as if i can ride a wheelie 800 feet, this bike is really being opened up.

Reply by robertbenita on 10/14/2010 2:12:37 PM
Finally got around to this and found mine was set at 2 turns. Now it's at 2 1/2. One more question as I am still well under warranty on my bike. Should I wait on the "Uncorking of the muffler" and if so, should I turn the screw back to 2 turns? Thanks in advance.

Reply by GlennF on 10/15/2010 10:19:34 AM
If you are concerned about warranty, put the brass plug back in where the fuel screw is. I don't think any dealer would look at it anyhow. Your problem opening the exhaust is that there are no available larger main and pilot jets for the teikei carburetor.

Reply by robertbenita on 10/15/2010 11:55:55 AM
Thanks for the responses. I was under the impression that uncorking the exhaust did not require any further adjustments to the carb other than making sure it was at 2 1/2 turns on the carb screw. Am I wrong, should I just leave as is or turn it back to 2 turns?

Reply by GlennF on 10/15/2010 1:17:57 PM
You probably won't have to do any more than the mixture screw at 2 1/2 turns with just the exhaust mod. If you open the intake and air box you would likely need richer jetting. My XT225 was much leaner stock. Screw was out only 1 1/8 turn and I went to 3 turns. I have modified snorkel, added UNI breather inserts so went up one size in main and pilot jets.

When you open up the exhaust, you might consider starting with a small hole--no bigger than 1"--in the baffle. I did a 1 1/8 hole because I had a hole saw with an extension shaft in that size. You might also try several smaller holes like 1/2" and add holes until it gets near being too loud.

Reply by robertbenita on 10/16/2010 4:41:25 PM
Thanks GlennF. I ended up having a hole saw blade 1 1/8 as well and went ahead. A little deeper sound, but the improvement off the line and through the gears was noticeable to me. Thanks much for the help everyone and I am very happy I went ahead with the mod. Thanks LILMINX!

Thought of one more question...How will these mods impact fuel mileage if anyone knows...

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