We've all heard of various tuning problems, but I have one that I hope one of you sharp guys out there will identify with and help me solve. (Please!) I am having a stalling problem under load that causes my Raptor engine to sputter, backfire, and even stall. This seems to only occur at full throttle. My carbs have been rejetted @ 160/165, and my airbox lid is drilled for added flow. Also have a pro-flow kit. One clue: the last time I rejetted, I found that according to the service manual, my float levels were too high. I adjusted them to the value that the book called for. I am wondering if the floats were set high on purpose by the factory? What have you guys found? I am trying to isolate the one event or change that I made to the bike that may have caused this problem, as it makes it impossible to enjoy my rides. I am goin crazy trying to find this gremlin, and need some feedback from you all, especially if you have had a similar problem. Have any of you noticed ill effects when adjusting float levels lower??? I even took the Sparks ignition advance key out that I just put in, thinking that may have caused my problem. I really feel like this is carburetion related. Please guys... any advise would be appreciated.

P.S. It's NOT a pinched vent tube...I already found that problem and corrected it.

 

try 155,160 on the mains
mine did it with 160,165 mains
I when down that cured it

 

Lets see....jetting seems to be in the pallpark....problem only occurs at full throttle.

First, I would check the plug immediatly after this problem occurs.
Is it sutty or white?
Sutty = has a main jet backed out and laying in the fuel bowl? Are you overoiling the air filter? Is something obstructing the snorkle that attaches to the air box lid?
White = main jet clogged? Is your gas tank filter clogged up (the one you can see where the gas exits the tank in route to the carbs)? Does the problem happen on reserve and standard fuel settings?

 

allright scott, have you figured it out yet?

i narrowed it down to my floats, i took it apart to try and fix a slight bog that i would get occasionaly, adjusted them to spec, and voila, its really running like crap, they were at about 8.5 - 9 mm, before and thats where im going back to, it wasnt that bad at all compared to now, now you can tell that its starving,

later

kevin

 

Scottd,
If this means anything, I have checked the float levels on both of my Raptors before, and both were set correctly from the factory. I even raised the float level on both carbs from one of them to 10mm (3mm higher than the factory recommended 13mm) to try to solve a lean problem I was having at full throttle with my pipe and filter setup, and that change made no difference whatsoever.

If changing the float levels back to their original position doesn't fix your problem, an easy way to see if you're too rich or too lean is to play with your air box lid. Cover the hole(s) in your lid with duct tape. If it runs better with the holes covered, you're probably too lean and you either need to jet up or maybe raise your float level. Or you can remove the lid completely and progressively cover more of the opening with duct tape. If the quad runs better with the lid off and with 3/4 or less of the opening covered with tape, you were probably rich and you need to jet down.

 

i moved mine to 8, about a m.m. lower than they were, and so far the slight bog i had is gone, mine is totally stock, so i figured it was a float problem, not a jetting problem,

later

kevin