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viking_in_wa

still got bogg.

11 posts in this topic

I did my BK mod a few weeks ago and followed the proceidures exactly. I shortened the duration of the spray and everything. I also re-jetted it with a 170, and its actually running a little rich now. I cannot get to the fuel screw, I cant even see the fuel screw. now i have an worse bogg than ever. any help would be great. this is an 02 426.

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I have owned one too.

I can't remember what the stock jets are, but my advice is to find a way to the fuel screw and learn to fine-tune the pilot circuit. I guess your bog is off-idle, right? The pilot jet and fuel screw adjustments should do the trick.

Remove the main jet and pilot jet and tell us what pilot jet you have there and where the needle clip is.

Main jet 170 has little, if nothing, to do with your bog. But if it went worse, change back.

Do you have the manual?

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yeah i have a manual and the main jet i took out, i think it was a 165. the needle is stock and in #4 position.

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Why would you only richen up the main? Jetting may be rich or lean from factory, but it is usually in balance. So if it needs to be adjusted, it needs it the whole way; pilot-needle-main.

I don't see a reason why you need a 170 main on a stock 426, or fatter jetting in general. I think it is a matter of pilot jet and fuel screw adjustment.

What pilot jet do you have there?

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the bike was running lean to begin with and all at once I did a big gun exhaust and the bk mod and was told i was going to need to re-jet and my buddy had a 170 main that i could throw in and try. not sure on the pilot maybe a 42.

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Go to this site...

http://motoman393.thumpertalk.com/

Do the on the fly fuel adjustment screw. Go to tech articles and see it for yourself. This way you can adjust it without any tools and keep the stock fuel screw in it. Not sure why you would do the BK mod and also rejet to a larger jet? Kinda defeating the purpose of the mod. Try switching the jets back to stock and keep the needle at #4 and then mess with the fuel adjustment screw. The fuel adjustment screw is vital to a 426 and often needs to be turned depending on temp, humidity and elevation. Try this first. What temp, and elevation are you riding at??

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I don't remember what main jet is stock, or wether you went richer or leaner....but the main jet has almost nothing to do with your bog....try making your pilot jet leaner (smaller). The air/fuel mixture screw shouldn't do that much if all else is good, I mainly only adjust mine when there is a big altitude change. The BK Mod, even though lots of you guys do it, is not a very good way to go...have you tried timing your squirt yet? What about drilling, tapping, etc.....lots of things to go wrong.

A lower pilot jet, a Power Now (or better yet, a Free Power Now-search TT) and a accelerator pump cover/atomizer (Boyenson, Factory R&D P-38) and Viola, no bog, snappy response, no big jetting head aches. Ask anyone of the guys with '01s or '02s.

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If you did the bk mod you will need to go up at least one size on your pilot jet if not 2. Next thing you should get is a zipty fuel screw because you will will more than likely need to adust it. After the bk mod in my bike i'm running a 48 pilot 172 main needles stock. I'm at 5000ft and the temp right now that i've been running in is around 40 degrees. Your stock pilot jet should be a 42 I believe. When you do the bk mod you get rid of the long squirt so you lean the pilot jet out and it needs to be richened up. Your main will need to be closer to stock more than likely.

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OK guys, I have finally got the problem solved. I re-installed my 162 jet and while i had the float bowl off i made a makeshift adjust on the fly fuel screw. and now the bike is running top notch, almost scary. thanks for all the good info guys. keep up the good work.

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