2003 660 raptor running issues - Yamaha YFZ450 Forum : YFZ450, YFZ450R, YFZ450X Forums
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post #1 of 3 (permalink) Old 02-24-2015, 09:28 PM Thread Starter
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Location: ohio
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2003 660 raptor running issues

picked up an 03 660 raptor and the guy said it runs fine and it does but you need to have the choke on all the time for it to run... then sometimes it sputters and dies when shifting gears. when you turn the choke off it completly dies and has a hard time starting sometimes. i took the carbs off and cleaned them and adjust the fuel mixture screw to 2 turns out each it helped alot but still needs to be choked to run which of course it idles high but runs decent. when i took the carbs off i took the top off the carb and the spring on top was broke in half i streched it out slightly and it allowed it to open the black slider easier on the one but it slightly less than the other. i was wondering if anyone had any ideas on where else to start looking? or any ideas new to 660s and that dual cartb set up..mods are gytr exhaust, k&n filter with the plate adatper, no air lid, supposedly jetted from what he said

2013 yfz450 white carbed, modded airbox, full yoshi exhaust,dyno jet needle 4th clip, 165 main, 2.5 turns on screw
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post #2 of 3 (permalink) Old 02-25-2015, 12:53 AM
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Join Date: Feb 2015
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Ok, lets start from the beginning...............I owned a 660 for ten years. Best dune bike.....Sorry dune Quad ever! Better than 700. Beat plenty of YFZ450z, banshee, you name it. All stock except for big 3 (pipe, intake, jets). Now, one thing about the raptor 660 is the carbs.......its all about the carbs. OK, first of all, sorry but you must take it apart again. That means rear, front fenders, gas tank, intake box, carbs (Always disconnect throttle cable at thumb assembly, not carbs its too fragile). Sorry about this, but your the one who bought a 660, but its ok, if you like dunes, or drag racing, this is your bike. Guarantee, the jets are still dirty!
2003 660 raptor running issues-carbs20explained.jpg
1. you must remove carbs(together as set, never separate).
2. Remove float bowls.
3. Clean inside of float bowls of any stains that you can catch with a finger nail.
3. You will see the goods inside of each carb.
Attachment 62665
4. All you have to do is take each jet and screw (flat head or hex as you can see in picture) out one at a time! an spray with high quality brake cleaner then blow with compressed air. repeat three times each, minimum, then reinstall. Do not over tighten, jets are soft metal. Use a drop (less than a drop) of blue loctite on threads, but do not let locktight get messy. (yes.......... you must used compressed air from a compressor) (if you don't have a compressor buy one, if you dont want to buy one then you have no business working on bikes, and you need to drop your panties and send your bike to a dealer to get.............well you know.)
5. Now look at the choke cable.......It has a hex head where it meets the carb housing...........get a wrench, remove the choke assy from carb........then spray the choke jets with carb cleaner, then blow with compressed air, repeat three times, repeat with choke assy. Coat O'Ring on choke assy with a clear type oil, like molybe, or engine oil, then reinstall.............. Reassemble float bowls. (Lock tight on bowl screws, blue, less than a drop.
6. Remove top cover on each carb, one at a time and clean needles with brake cleaner, then wipe with a rag, repeat three times.
7. When you reassemble top of carb, make sure top indentation of carbs are clean, lubricate rubber skirts with a rub of engine oil to ensure a good air seal.
Spray all crevices, holes, and anything you can think of front to back on carbs with break cleaner, followed by compressed air.

8. Install carbs and air box.............now since you have everything apart....................install air box............before you install air filter, put your finger down the airbox intake tubes towards the carbs..........feel where the carbs meet the intake boots from the airbox.............If you feel where the boots meet the carbs and you that the boots have a smaller inside diameter where the intakes meet the carbs, remove air intake boots and boar inside of airboots where they meet carbs with a dremel tool to match inside diameter of carbs or make the intersection between the two smooth. This will open air intake just a little bit, but will make all the difference in the world. All you need is a little more when you are already pulling away.
9. drain fuel in fuel tank, replace fuel with fresh fuel.
10. Reassemble.
11. Start bike with choke on, let warm up for 5 min.
12. Close choke. Ride bike. Have fun.
13. Start bike no matter what once a month to keep fresh fuel in float bowls.
14. One tip, when you are done ridding for the day with bike still running, turn fuel off and keep running till you run out of fuel. This will almost empty carbs and help keep clean.
15. NOTE...........This assumes carbs are tuned for you elevation. Check main jet numbers (on main jets) then check dynojet website for jet numbers.

If your bike bogs when you open throttle, then you are ritch.
If your bike hesitation at low RPMs then you are ritch on your pilot.
When your bike pops you are lean.
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post #3 of 3 (permalink) Old 04-08-2015, 06:09 AM
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If you feel where the boots meet the carbs and you that the boots have a smaller inside diameter where the intakes meet the carbs, remove air intake boots and boar inside of airboots where they meet carbs.
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