My 01 Raptor Started acting stupid...It won't idle right and "pops" through the pipe and carbs. If I turn the choke on a little it seems to get better, but the idle speed goes through the roof, (probably lean right?),That is a possibility however, I HAVE checked the boots for leaks, and no, my carbs did not pop out. The only aftermarket part on the engine is a White Bros. R4 slip-on,and a 11 tooth counter sprocket, after installing that I richened my idle screw 1/2 turn and flipped the washers around on the needle (as per my dealer).
I rode the machine last weekend and the air temp was about 65* and it ran great..now this week the air temp was about 70* and we were at the same elevation (300Ft.). And it ran great all morning and about 2hrs into our ride this problem just "developed". The mains and pilots are all stock sizes. Got any input?? Thanks!!

 

One word. DYNOJET. You're too lean. The Dynojet (or K&N Stage 2, same EXACT kit) comes with new needles (the key part), new jets, new diaphram spings for the slides, and detailed, illustrated instructions. The key is the slimmer needle, which richens across a broader spectrum. Just buying new jets at the dealer won't get you the same results. The great thing about the kit is you jet ONCE and you're done. I've got a K&N air filter and the Dynojet, and it made a noticable improvement, even with a stock pipe. From what I've read, the Dynojet alone adds 10% HP, Dynojet/K&N air filter/slip on pipe adds 30% HP. Cheapest place I've found it is www.rockymountainatv.com for $50.00 plus shipping.

 

95 Warrior, Hey thanks for the input. I'm gonna try the kit..filter and all. Another thing I forgot to mention is that I went from running 94 Octane fuel to 110 racing fuel(actually the wife just reminded me). but that still is weird that it ran OK for two hours that morning and ran fine the week before in cooler weather....you think the fuel could have made that much of a difference?I'm not arguing I'm just trying to gain knowledge, I come from a Honda 250R background and this is the first 4 Stk I've ever owned. I know the two strokes don't seem to respond to the higher octane the way the 4 stroke does.

 

95Warrior is dead right about getting a Dynojet kit. The needles are well worth the price. This isn't your whole problem though. Your wife is right too. Go back to pump gas. There is no reason to run high octane gas in an essentially unmodified engine...in fact, you can actually cause damage.

Good Luck.

 

Notu, Octane can damage a engine? (again I'm not arguing or being smart..I'm just investigating). I was under the impression the more the better. I know new vehicles(cars&trucks) say not to run it but that's because of the possibility of a methanol blend eating o-rings,lines, ect.[img]i/expressions/face-icon-small-shocked.gif[/img]

 

I am not sure on the damage question, but I do know that with the engine being stock internally you will not be gaining anything by using the higher octane (you may actually lose power). I use 92 pump gas and mine runs great.

Again, I am not sure about causing damage, but it could. I would bet that your quad will run much better on pump gas.

Paul

 

Do an advanced search on octane and read the posts. There is lots of good information.

In a nutshell, a stock Raptor engine doesn't have enough compression to support the slower burn rate of really high octane gas. You will end up with a build up of fuel additives.

/NotuRaptor

 

Notu, that makes 100% sense...thus leaving more deposits on valves,plugs,pistons,ect. Hmmmm. Never thought of it that way.. basicly the cylinder temp never gets high enough to complete the burn cycle, resulting in pitiful volumetric efficiency. Heeyyy now I get it!! How 'bout this mod I here about: chopping up the air box lid?? is really worth it?? If so how much would be a good amount to cut off?

 

I cut off everything but the front 2" with a tablesaw. I use this front section to lock the White Brothers PowerFilter in place. This works great for knowing that the filter is locked in properly.

I am not sure if or how much more it helps a virtually stock engine breathe versus just drilling a few holes in the lid. I do get some water kicked into the air filter box when crossing through 6-12" deep water holes but it doesn't seem to hurt anything. I am never in really deep water so I just leave the drain plug out of the air filter box. Kevin's Cycle sells a one way drain plug that I thought about getting.

I've been thinking about drilling holes in the back portion and using it again just to try to stop some of the additional water from getting in. I've also thought about covering the air filter with the foot portion of women's pantyhose. I recently read in a 4 wheeler magazine that offroaders do this. No matter what, I do not regret cutting the lid. I need to know that filter is locked in properly. I also know that you get added power from having the lid off or holes drilled in the lid as long as you rejet the carb properly. Raptor720 once quoted a 5 hp gain on the dyno for removing the airbox lid and rejetting but I am not sure if that was with a stock or a modified engine.

/NotuRaptor

 

modifying the air box does make a diffrence.i have 2 3 inch holes in the lid twords the front.to cut down on dust i put a pantyhoe over the whole lid and installed it.i have never had a problum with water..depending on temp and humidity i can run no lid ,tape over one hole or tape over two holes thus adjusting my jetting through out the whole rpm range by regulating air flow.
i did mine in steps,pipe jet kit pro flo filter than when i had it all set up and was uesd to it i modifed the lid and it made a diffrence.