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Discussion Starter · #1 ·
i just rejetted my raptor and after it warms up the idle doesnt stay steady. if i rev it sometimes the idle will stay really high and sometimes it will go back down to normal. when i did all the jets everything in the carb seemed to be really clean so i dont think its dirt or garbage in the carb. anyone have any idea?
 

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i just rejetted my raptor and after it warms up the idle doesnt stay steady. if i rev it sometimes the idle will stay really high and sometimes it will go back down to normal. when i did all the jets everything in the carb seemed to be really clean so i dont think its dirt or garbage in the carb. anyone have any idea?
Why did you rejet and what was the jetting before, what mods have been done to the bike now.................
 

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Discussion Starter · #4 ·
ok so heres the story....i bought an 01 raptor that was running shitty the kid told me he tried rebuilding the carbs and stripped some of the jets so it needed a set of carbs the silencer was totally gutted and it has some cheap aftermarket foam filter with no airbox at all. so i bought a used set of carbs, a slip on and a jet kit for the used carbs because they had 170 mains in both carbs and no fuel mixture screws. so yesterday i got all the parts in and put everything together and its running alot better but when it warms up it idles really high after you rev it up. but if i put it in gear and hold the break and slowly let the clutch out till it idles down it will stay idled down if i pull the clutch back in untill i rev it again. im not the greatest at adjusting the carbs thats for sure lol but i set the fuel mixture screws at 1 1\2 turns out like the directions said to and i tried going out and in and i still get the same results.
 

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ok so heres the story....i bought an 01 raptor that was running shitty the kid told me he tried rebuilding the carbs and stripped some of the jets so it needed a set of carbs the silencer was totally gutted and it has some cheap aftermarket foam filter with no airbox at all. so i bought a used set of carbs, a slip on and a jet kit for the used carbs because they had 170 mains in both carbs and no fuel mixture screws. so yesterday i got all the parts in and put everything together and its running alot better but when it warms up it idles really high after you rev it up. but if i put it in gear and hold the break and slowly let the clutch out till it idles down it will stay idled down if i pull the clutch back in untill i rev it again. im not the greatest at adjusting the carbs thats for sure lol but i set the fuel mixture screws at 1 1\2 turns out like the directions said to and i tried going out and in and i still get the same results.
I assume the bike is running fine otherwise. A hanging idle is a lean condition on the fuel/air mixture circuit. If you're bike revs up high RPMs and stays high for 2-3 seconds then drops to normal then you need more fuel air screw (more fuel); about 1/4 -1/2 more turn out (ccw) on both carbs. But if the RPMs are high and seem to never go down you may have a boot pulling in air from the intake clamps or maybe even the airbox side of the carb. Check for air leaks. Check your throttle cable is free and not binding or kinked. Check you choke is working properly. Check you idle setting screw. Good luck
 

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So, with no airbox lid and a slip on, you should be running something like: 155L/160R Mikuni mains, 25 pilots, aftermarket needles near center notch, fuel screws somewhere near 2 turns out.

You will have to tweak each based upon the following:

Pilot jets control idle to 1/4 throttle, throttle response from idle and slow return to idle (hanging idle). Fuel screws are valves that reduce flow through the pilot jets - full in is nearly zero fuel at idle, 3 turns out is near full flow thru the pilot jet. Max flow is set by the pilot jet, the screw dials it down from there. 22.5 is stock, but has always been a bit lean to meet EPA req's... with lid off, 25 is necessary.

Needles control 1/4 to 3/4 throttle - aftermarket needles have a more aggressive taper and are necessary when the airbox lid is off

Mains control 3/4 to wide open throttle. - absence of airbox lid typically increases the main size necessary by 15 to 20.
 

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Discussion Starter · #7 ·
ill try the air fuel screws again when its not raining and i should be running 155/160 instead of 150/155 mains? i have #25s and needle clip on the 3rd setting which is the center.
 

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150L/155R may well be too lean for the open airbox. Some run as high as 165L/170R or more - it depends on the particular bike/engine.

3rd clip being center implies stock needles, if I recall (5 notches) - you need aftermarket needles with open airbox (they usually have 6 notches).
 

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Discussion Starter · #9 ·
they are aftermarket needles i bought a vitos jet kit and it only has 5 notches. im going to check over the boots for the carb and if i dont find anything ill try 155/160 mains
 

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I had a similar issue with my rappy. It ended up being the spring that syncs the two carbs together. There is a screw adjustment on the spring between the two carbs. What was happening was the tension on that spring was too weak to fully close the butterfly on the second carb. I just played with that screw a little bit until both butterfly's were shut when I let off the throttle and they both opened up at the same time when a little throttle was applied. This took care of the problem for me. Might want to see if your butterfly's are fully closing when you let off the throttle.
 

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they are aftermarket needles i bought a vitos jet kit and it only has 5 notches. im going to check over the boots for the carb and if i dont find anything ill try 155/160 mains
You will need #25 pilots.........
Aftermarket needles half way up............
160 and 165 mains...............mikuni style..........
 
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