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Discussion Starter #1
I have a friend who owns a predator. he recently ordered a slip-on, drop in K&N, and jet kit from rath racing. We did the airbox mods and jetted according to the directions. But now it just dies down from half to full throttle. No back-fire just bogs. I have tried EVERY needle and main jet combination POSSIBLE with little to no change. It has to be something disconnected or faulty. I changed the plug - no change. What could it be? PLEASE HELP!
 

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generaly around 3/4 to full throttle is main jet territory
did you possible harm the float during mods?
 

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Discussion Starter #3
how do i check the float?
 

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I've found that rejetting is unnecessary with the pipe and drop-in filter, at least not around 4000' where I live. Down around sea level, I'd go no higher than a 155 main jet and leave everything else alone.

If it's too rich, it will have no upper-end power... so every time I've dinked with mine, I've put it back to stock.

Rob
 

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Hi DaIronFist,

Try the intake boot at the carb (the plastic round-to-oval shaped piece that joins the carb and airbox), and see if it is shoved ALL the way on to the carb mount. If it's not, it'll suck air real bad and do just what you described. It happened to me and took me about an hour of trial and error to find the problem.


Good Luck,

JJ
 

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Discussion Starter #7
yea the intake boot is all the way on
 

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Well in that"magic jet kit" what SIZE main jet did you put in?

If its a steady bogggg at WOT throttle, sounds like you're too rich.

Try putting duct tape in small increments over the airbox mod (leaning it out) to see if this helps out.......if you're too rich, it should help make it crisper.
 

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Check the diaphram attached to the slide, make sure there isn't a hole in it and be sure it is in the proper location when you attach the top cover. Any leak here and the slide will not open and you have have a major lack of power...
 

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We got it fixed, we used jets from the dynojet kit and raths kit and took all the spacers off the needle. Now it run like it should and the plug looks great, it makes power like a 2-stroke all the way to the limiter.
 

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Discussion Starter #11
yea we adjusted the float too. Have a feeling that it was the float. Those spacers on the needle arent worth much anyways. Thanks for all the help guys!
 

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I'VE PLAYED THIS GAME TOO AND FOUND THAT A 155 MAIN AND 55 PILOT WORKS GREAT. A BIG MAIN IS ONLY NEEDED FOR COLDER WEATHER OR BIGGER BORES.
 

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I am having the same problem as DaIronFist stated in the original post. I have a W/B slip on, K&N drop in and the Rath airbox mod (160 main, needle clip 4th position) I have tried everything(165, 157, 155, 152, 150 mains and needle clip in every position) and it still falls on its ass @ 1/4 to full throttle. I am thinking it must be the float but do not know how to adjust. Please give me any suggestions/ideas you may have. I am about ready to throw the carb off a bridge. I live at about 500ft

Thanks a million
 

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DaIronFist was refering to my bike, which was doing exactley as yours is, the guy that fine tunes all our carbs adjusted the float and that fixed it. Before he did that we tried every jetting combo possible and nothing helped or worsend the problem. My bike has the 160 main the larger pilot and he ended up taking some of the spacers off the needle to get it perfect.
 

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Thanks a lot for the info. Do you by chance know what he did to the float or how to adjust the float?
 

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I'm am not sure, he adjusted it once and it leaked a little out of the hoses, so he had to go back and re-adjust a little. Just to get rid of the possibility, try putting that little black air tube back on your airbox and not using the circle shaped outerware that rath puts in the airbox mod kit. My bike runs perfectly right now, but if I put that outerware over the stock tube, or take the tube off and put it on the airbox like rath's directions say, it runs like garbage again. It'll start and idle fine, but as sonn as you try to go it pops and sputters again. I'd try that first, maybe you don't even need to adjust the float.
 
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