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2001 Yamaha Raptor 660 Idle Problems


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I would start with the The jet needle.... its most effective between 1/4 through 3/4 throttle and wont cost you a dime if works....Also The air screw is most effective between idle through 1/8 throttle......that also will not cost you anything....Dont do them both at the same time though....Make a Change and Test it....If that doesnt work...Move to the Second Operation and Test.....Also,,,,Whenever I drill Holes,,,,I Sneak a pair of the Wifes Panty Hose thingies and Cover my lid.....Kinda like a Pre Filter....:wink:

Oh BTW......Make DAMN SURE you are Checking your PLUG!!!!!!!

.

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so i covered up the whole on the air box just to see if it would make a difference and i rode it for bout an hour and it seemed to fix the problem. it still idles a little rough and every once in a while when its idling it will die unless i turn up the idle a little bit. i dont know if thats just becasue its an 01 and its got some miles on it. what do you guys think

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Sounds to me like it is lean. You can jump up 1 size pilot jet. I would recomend the Dynojet kit, it is the easiest and fastest, they have done all the testing. You can also make changes later with the same kit if you add any more performance parts. Jetting the Raptor is a huge pain in the rear without the Dynojet kit

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Sounds to me like it is lean. You can jump up 1 size pilot jet.

I am going to have to Disagree with you there..

If your main is too rich, the bike will sputter and surge as it tries to burn all of that fuel.... Too lean,,,, and the bike will run flat or have a flat spot in the powerband... A severely lean main will cause your bike to seize just like a two-stroke.. It's better to be slightly rich on the main than slightly lean, because it will run cooler.

Your pilot jet (or slow jet) controls the idle circuit, or from zero to one-quarter throttle opening. The pilot jet and airscrew control the amount of fuel and air going into the engine at slow engine speeds. It's very important to tune these circuits because they control throttle response and starting.

When you are Tuning, Make sure you are at operating Temp.

One Question that has never been Asked..Do you know what the Stock Jetting is and What you are running now????

Another thing.....There Really is NO POSSIBLE way to Jet a Carb over the Computer...You either know what you are doing or you dont...Plug Chops are KEY IMO when Jetting...You dont know if you have done it right until you read the plug....

Do us all a Favor......Install a new Plug......Do a Plug Chop.....Immediately take that out and snap a Shot.....(to post here or reference for yourself....) That will give you a starting point....Each time you Jet.....You need to install a new plug.....Keep reading them until its Right....

Everyone has given Good advice....I just think at this point we need to stop and Start all over again.....

:laugh:

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i bought it about a year ago and i have no idea if its the stock jetting or not. i did take out the plug and noticed that it was really dry.

You're running too lean. Your air/fuel ratio is off. I would plug that hole, clean or install a new filter, and install a new plug.

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i bought it about a year ago and i have no idea if its the stock jetting or not. i did take out the plug and noticed that it was really dry.

The idle problem may be remedied by adjusting the air screw. Did you notice the dry plug before or after you plugged the hole it the air box? What color is the plug?

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Your pilot jet (or slow jet) controls the idle circuit, or from zero to one-quarter throttle opening. The pilot jet and airscrew control the amount of fuel and air going into the engine at slow engine speeds. It's very important to tune these circuits because they control throttle response and starting.

it sounds like i need to adjust my airscrew becasue i chokes at slow engine speeds ill try that this weekend. how do i go about doing that

Edited by raptor_rider
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It is a screw on the side of the carb, should have a spring on it, you probably can't see the spring unless you completely unscrew the screw, but you can feel it when you turn the screw. It will be low on the carb, but not in the side of the float bowl. Turn the screw in to richen, out to lean it out. Adjust the screw so that it idles smooth and the throttle response is good, no stuttering. However, you also probably need to either make sure the hole in the air box is sealed or, go bigger on your main jet. Follow MWKE's advise and get a coulple of plugs and do some plug chops. Make an adjustment, install new plug start the bike, warm it up and ride, get the bike wide open in as high a gear as possible then pull in the clutch and hit the kill switch. Pull the bike over, take that plug out, put your old one back in, and ride back. Take the plug you removed and chop the side of the threads off so you can see the lower part of the insulator. You want to see a medium to dark brown color. Light gray means you are running too lean. You either need more fuel or less air. After you get the main jet set, then if needed tune the needle and pilot if you think you need to. Also, you may want to search for some jetting tips on your browsers search engine, google works best IMO. Reading a good article on jetting will help you understand what you are trying to accomplish.

Edited by DirtDemon
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do you have the ability to take a good picture of the Carb and post it???? We could then Circle it and show you......My next Action would be to drive down to the Yamaha Shop and Buy a Manual before they close....:wink::yes:

No offence to you....I know(just like me) some people dont learn unless they do....But this is a Pivotal part of the machine....If the carb isnt set right...Your next post will have the heading...."My Engine is Locked up, What do I do?":huh:

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