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Larger Spark Plug Threads

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Just bought an 01 XR250 and got around to checking the plug. What do you know the dang thing stripped as I was removing it. I have read alot about inserts but was just curious if anyone hear has just drilled and tapped for a DR series plug instead of a CR series? DR9EA appears to be the same plug just larger threads (12Mx1.25 vs 10Mx1.0). Any help would be appreciated. Thanks!

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My 03 xr250 was like that when I bought it,just tapped hole CAREFULLY as you explained,ran great. Don't remember plug number,but got smallest hex wrench size plug I could find on interchange charts,in similar heat range. Didn't take much drilling,but pull head so you get it drilled parallel to original hole.

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If you go bigger, you may have some trouble getting a socket down in the head cover to take it out in the future.  You have to really reach down in there to get the plug.  I have a lot of trouble with mine, which was drilled out and tapped for a bigger plug one time by a shop.  Apparently they did the same thing and did not tell me, and I did not find out until I had to take the motor out to get the plug out.  

 

I had to use a vice grips to get it turned out.  Once I did, I took a dremel tool to the head to give me a little more clearance around the hex part of the plug and now I can at least get a socket onto it to take it out.  

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Is there something about a heli coil that you don't like ?

 

I've used them a couple of times (very easy) without any issues and you can find kits on ebay for less than $25.

 

Perc

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Thanks for the replies. I am just a little leery of a heli coil lasting over time. What length insert do I need? I haven't pulled the head yet to measure and I am wanting to to get it ordered first.

Edited by kingsxjt

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Thanks for the replies. I am just a little leery of a heli coil lasting over time. Never been a fan of them.

 

What aspect about a helicoil are you concerned about not lasting?

 

The threads of a helicoil are stronger than the original aluminum threads and will not pull or strip like the aluminum when installed properly.

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What aspect about a helicoil are you concerned about not lasting?

 

The threads of a helicoil are stronger than the original aluminum threads and will not pull or strip like the aluminum when installed properly.

 

 

 

Coming loose. Just found out that the XR250 requires a special time sert kit and they are $240. Looks like I may be just drilling out for the M12x1.25 plug.

Edited by kingsxjt

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The plug won't come loose with a helicoil if done correctly. (straight)

You don't have to pull the head either. You. May need to pull the engine though.

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Coming loose. Just found out that the XR250 requires a special time sert kit and they are $240. Looks like I may be just drilling out for the M12x1.25 plug.

Besides replacing the head a time sert would be the best way to go. Call your dealer about ordering just the time sert your need or see if you can buy individual ones online, you must be able to.

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I guess I could buy the head new but then I'm looking at machine work on the valves. Is there anyone who sells heads with new valves, springs and seals already in them?

Edited by kingsxjt

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