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o-ring mod

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I did the o-ring mod on my 250x and it worked great, the bog was completly gone. This was done after the bike was rejetted and was running great except for the little bit of bog that was left. After the success with the 2006 250x, I decided to do it to the 2007 WR250. Also after the WR was rejetted and all the mods to the intake and exhaust, gray wire, yz cam, etc. The 0-ring mod was a complete flop. The bike has less bog without the o-ring mod. The bog on the WR is not all that bad but, I was convinced that I could make the bog go away like on the 250x. Anyone else find that in some cases the o-ring mod did not work for them?

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Did you read the entire thread regarding the mod?

There is more to eliminating the bog than just the oring. You need to have the correct size leak jet for the type of riding you will be doing and ensure the AP timing screw is set so the squirt just misses the slide.

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I took a lot more time with the Honda and checked it all out, worked great. The Yamaha was set up by a previous owner and I did not check everthing as well as I should have. Bike ran great and the jetting seems to be dead nuts on, I will check the timing and squirt. The bog was slight enough that I thought I could get away with just adding the o-ring.

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If it was a simple as an Oring makes it better they would come that way. The Oring is one of many ways to adjust the AC pump which in this case is to increase the fuel pressure in the pump chamber

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