I just purchased a 2006 predator 500. It ran pretty good but the gas was deffinately skunked. What it has installed HMF pro balance header and muffler with torque tube, K&N drop in air filter and HMF jet kit. All the work was done when I bought it I don't know by who honestly. I am alittle curious it doesn't seem to hold an idle very well, so I pulled the carb and started to clean it out. After a few curses swears and a few [img]i/expressions/beer.gif[/img]'s I finally got the float bowl screws out with alittle help from some vise grips [img]i/expressions/face-icon-small-disgusted.gif[/img] . Well I did get the extra jets when I bought it, so I looked to see what was in it. This is where the confusion started. The jet with the shroud (main I think) was smaller(150) than the one just in the open(155)(mid I think). Hence the question, is this right? I am not a pro by any means, but I think they are reversed. Please correct me if I am wrong or tell me I am right. I want to try to put it back togeather ASAP for this weekend. On another note ethenol sucks. Tons of varnish inside!!!!

 

the main jet is the on in the bottom of the float bowl. usually a hex head. there is a pilot jet that takes a flathead screwdriver to get out. the pilot jet is the one that your gonna need to take a look at for idle problems. let the bike get nice and warm then let it idle for about 2 minutes. immediatly kill the motor and pull the plug out. if its white/ashy looking its too lean, need a bigger pilot. if its black and carboned up then you need a smaller jet. brownish tan with maybe a little bit of carbon buildup is about right

 

The pilot jet is off to the side correct I think. Kinda looks like a stem rather then the others. The main is inside the head but does come out alone. Is it right that the midrange jet is smaller then the main?

 

Oh how I love jetting! I have an 07 preddy with an HMF header and exhaust, umf airbox, kn filter, no lid, Dynojet kit. I have it dialed perfect. It runs perfectly, no spitting, backfire, black smoke, etc. Plug is a nice light chocolate color. My dynojet kit came with excellent suggestions. I am at 4200 ft elevation, so I had to tweak a bit. But, it fires right up with one push of the starter every time no matter how long it sits. I think I can help you along here and also offer some suggestions. To begin, removing the float bowl screws is a bit@# and it does take vice grips otherwise they will strip as the screws are soft. I replaced mine with allen head screws you can get for a couple bucks at home depot. It makes future access much quicker and easier. The main jet does not have a hex head, it is a flat head. You said you got the extra jets with the atv, but did you get the instructions or something along with them? Do you know if the needle was replaced or adjusted? You started out right with cleaning the carb up to eliminate any contaminants. You may also have to adjust the air screw mixture. I think it will be better for you to start all over from scratch so you're not trying to fix someone elses mistake in case they did not properly jet it. When I get off work tomorrow I will find my instructions and try to walk you through them. Just let me know your elevation. There is are some good websites that explain the jetting process in great detail that may be good reading tonight if you have time. Just google it or look up predatorowners.com. It is another forum for just preddys.

 

<div class="FTQUOTE"><begin quote>Originally posted by: gn386

The pilot jet is off to the side correct I think. Kinda looks like a stem rather then the others. The main is inside the head but does come out alone. Is it right that the midrange jet is smaller then the main?</end quote></div>

The pilot jet is much smaller than the main jet, which is the one in the "shroud".

 

Fire hog I am searching as we speak. Thats right the shrouded was smaller then the non shrouded. aint tht wrong. if you take the shroud out it has the needle tip exposed. nope no instructions. I know I am a low altitude Richmond area VA

 

I can't remember what my main jet is or the pilot jet. I have them on my computer at home and written down in my manual for reference so I will have to get back with you tomorrow. Your pilot jet should be like 42.5 or something. If it is 155, then it is no wonder you are not idling. The main jet doesn't come into play until like 3/4 throttle if I remember right. I always have to refer to my publications I have printed off the web as, fortunately, ever since I have been running four strokes, I haven't had to rejet unless I go to the coast. When my son raced a blaster, I was rejetting all the time and it came easy.

 

Okay, so stock jetting is: Main Jet - 150, Pilot Jet - 42.5, Needle - 2nd groove, Fuel Mixture Screw - 2.5 turns counter clockwise. MY jetting at 4200 ft elevation with the above mods is: Main - 170, Pilot - 42.5 (no change), Needle - 3rd groove (replaced with better one from kit), and Fuel Mix Screw - 3 turns ccw. If you are at sea level then try a main jet of 175 and keep everything else the same.

If your fuel mix screw has not been adjusted before, you will need to drill out the plug that hides it with a 5/32 drill bit. Be careful and go slow as it is soft and you could damage the screw right behind it. To properly adjust it turn it clockwise until it is tight (closed) then back it out ccw to the settings above.

One important thing to remember is always perform one change at a time and document it. This will keep you from getting into a big mess and confusion.

Make sure your carb is completely cleaned out so you don't encounter problems with plugged needles, etc. that can throw off your whole jetting procedure.

Let me know what you come up with after the above changes...

 

Worked on it alittle tonite. He def had the wrong jets in place my corrections so far are as follows Main with the shroud now has a 160 instead of the one 150, pilot the straight up from it nowhas the 42.5 rather than the 155 he had in it. Drilled out the plug and reset it to 2.5 turns rather than 2.25 just to start out. Cleaned it all up with carb and choke for small engines and blew some air through the passages. All seems to be clear and free and reassembled. The only place I lost ya was the needle, where what are you refering to? I did pull the third jet long one totally different from the other 2, and found one hole on the end/side colgged so I cleaned it also and reinstalled. The only issue is my son came down just as I was rolling it out to start, dammit if he didn't say goodnight daddy. So the journey ended for tonite. I will keep you up to date when I start it tomorrow.

 

Sounds like a good start. I think your main jet will go up, but you will find that out as we move forward. The needle I was referring to is on the top of the carb. There are a couple of screws that are also hard to get out (again, replace them with allen head screws). Inside is a vaccum diaghram. Beware that it is spring loaded and the spring will pop out and seems to disappear on a concrete floor! LOL! The needle has grooves and a "c" clip. It is held down by a plastic tab that has to be removed with long needle nosed pliers. It is fragile and can be broken easily. It does not screw in, it is held in with a rubber gasket so just gently wiggle it until it comes out. I know it is a pain as I have broken one before. I happen to carry a lot of these extra parts just for the occasional mistake! [When you look down the barrel of your carb you see a needle that is sticking out in the middle of it all, that is the bottom of needle, it moves up and down with the throttle]. A good jet kit comes with a better needle than the stock one. I don't know if yours has been replaced....hard to say. But, we can work on the needle later. It won't hold you up from the main part. It may even be set right now if the previous owner adjusted it, then it will save you some time. But, my guess is, judging by the fact that he replaced the pilot jet with a main jet, it hasn't been touched. Especially if he obviously hasn't adjusted the fuel mixture screw. We know that for sure since you had to tap out the plug. I know it sounds like a lot, but it is really easy and you will soon catch on to it quickly and see that it is kind of fun! Truth be known, most motorcycle mechanics, atleast around here, hate jetting and try to avoid it! But, it just takes time and patience. I'll check back tomorrow....