First off, I want to THANK all of you guys that have tried so hard to be of assistance to me as I've been working through this persistant problem on my machine. Especially to RAPTECH for all of the great advise and offer to help me with the CDI thing. I want to let you all know how it's going. I must say I hope none of you ever have to chase something so maddening as this problem has been. A fellow raptor owner here in the Phoenix area was kind enough to loan me his CDI for an evening, so I could see if it made a difference. (Thanks so much, Mark!...aka Atvinstructor on this forum) Well, let me just say that the search continues. It was NOT the cdi unit. I now have totally eliminated the ignition system as a problem. I now know that this is carburetion related. Why doesn't anyone else with similar jetting/air box modifications have these symptoms? I don't understand it. Can't imagine what could be possibly causing this glitch in my carbs, as everything has been checked. My Raptor is running out of fuel under high rpm and demand and stalls out and dies. The only thing that I can think of now is to replace the needles/seats, and floats and see if that takes care of it. Why can't these carbs keep up with fuel demand? So, it's back inside the damn carbs for the umpteenth time...what could I be missing? Can I not see the forest for the trees? I guess I'm making some progess, because I'm eliminating things as I go along. I'm just glad I didn't go out and buy a cdi unit for nothing...thank goodness for these forums and the great people that help. Well, keep the suggestions coming...I'm gonna solve this dilemma if it kills me! Thanks again, everyone!!!

 

This may not apply to your particular problem. But awhile ago I had a similar problem with my Griz. After looking at everything I could think of, and actually taking it to the dealer for them to check(warranty), I found out that I had my gas cap on too tight! It has a little metal ball in the gas cap that prevents gas from spilling out through the breather tube in case of a roll. I could hear the damn thing rattling around when I was riding, so I tightened the crap out of it to keep it from rattling. That prevented the gas tank from breathing correctly and was causing it to run real bad. Especially after the tank got more then half empty, or when going up hills after the engine was warm. When all was said and done, it was the simplest solution that worked! Jeez, I wanted to just kick myself! [img]i/expressions/face-icon-small-smile.gif[/img]

Rick

 

Take the fuel supply line of the carb. and let it run into a bucket to see if you have good fuel flow out the hose. Check your float level in the carb. too. If the float level is too low you might run out of fuel when held wide open. Loosen up the gas cap a little and take it for a run wide open, that will tell you if the breather to the gas tank is ok or not. Maybe the quad is not running out of fuel, it could be running out of air. Have you cleaned the air filter? Also is your exhaust blocked in anyway not allowing the exhaust out?

 

THIS MAYBE A LONG SHOT BUT I HAD THE SAME SPUTTERING ON MY RAPTOR AND IT WOULD DIE AS SOON AS I GOT ON THE GAS HARD. AFTER CHECKING MY JETTING, CHANGING CDI UNITS AND A MILLION OTHER THINGS IT TURNED OUT TO BE BAD GAS AFTER I DRAINED THE OLD GAS AND PUT NEW IN IT EVERTHING WAS FINE

 

All of the above items have been checked out and eliminated as problems. I have an aftermarket gas cap with no check ball in it. Fuel runs out of the supply hose freely. Clean air filter, no exhaust restrictions. (Yoshimura pipe) Great suggestions though. I'm thinking the problem has somehow got to be inside the carbs. It just makes no sense! Hopefully the demons will release my Raptor soon. Everyone keep thinking!

 

Spark plug...weak under high pressure?

Have you checked your plug after this happens occurs? what does the plug look like afterwards?

are the fuel slosh tubes still around your mains? The main jet actually sits in it.

what about a loose connection sucking air somewhere? Intake boots? What about a small rip in the intake boot that sucks air up under the most demanding conditions? The plug that sits atop the left boot fall off???

When did you buy your Raptor? The first design intake boots were very weak....potentially collapsing under hard acceleration of your modded Raptor?

intake tract somehow collapsing or snorkle getting obscured under hard acceleration by some object?

choke partially hanging closed? Somehow sucking closed?

heres another one....one of the carb diaphrams could be torn or the slide could be scratched/broke? Are both needles the same length?

could their be slack in the carb linkage allowing one carb to be wide open and the other to be only partially open?

problem with the aftermarket exhaust somewhere inside? Does this happen with the stock exhaust bolted back on?

valves need adjusted??

main jets in incorrect location....left one larger than right?

 

Hey garyc660R,
I gotta say you came up with some good suggestions there. Keep up the good work!!![img]i/expressions/face-icon-small-happy.gif[/img]

 

jet up.

 

Hey DerbyKing

Hae you changed out your stock carbs for Keihins yet?

 

Hey Nakedraygun! I've thought about changing the carbs at this point...Give me some more info on what is available and how well they bolt up and interchange. What performance difference did they make? I think that I would be happy though just to get my damn problem fixed with the stock carbs.