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Discussion Starter · #1 ·
I have a problem with my Raptor 660 that i hope someone can help me with.
Although the bike starts on the touch of the button, on start up the bike would only idle smoothly at around 3000 rpm (purchased bike like this), any adjustment via the idle adjustment screw, under 3000rpm or so, the idle doesnt seem to retain its smoothnes.
Another problem i have encountered with the bike is that whilst riding the quad will occasionally pop on deceleration throught exhaust and if revved up a good few times on idle will do the same but more often.
I dont think the bike is running lean due to the spark plug being mostly black.
Could this be symptoms of wrongly adjusted fuel screws?.
Ive already tried to adjust them but they're so F*****G hard to get to!!!!!!.
This problem has led me to order extended and knurled fuel screws to make life easier.
Ive checked for vacuum leaks by spraying carb cleaner, all seems fine.
The floats have also been set following 'Clear tube' methods and carbs cleaned.
The valves have been adjusted.
All these problems remain even after performing the above steps so i can only think it is related to jetting.
I would also like to know, when checking fuel/float level on the carb via clear tube, if fuel level in the tube remains at a certain level can this be used as an indicator that the needle and seats are fine and fit for purpose?

Appreciate if anyone can help.
 

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I am unique
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22,621 Posts
I have a problem with my Raptor 660 that i hope someone can help me with.
Although the bike starts on the touch of the button, on start up the bike would only idle smoothly at around 3000 rpm (purchased bike like this), any adjustment via the idle adjustment screw, under 3000rpm or so, the idle doesnt seem to retain its smoothnes.
Another problem i have encountered with the bike is that whilst riding the quad will occasionally pop on deceleration throught exhaust and if revved up a good few times on idle will do the same but more often.
I dont think the bike is running lean due to the spark plug being mostly black.
Could this be symptoms of wrongly adjusted fuel screws?.
Ive already tried to adjust them but they're so F*****G hard to get to!!!!!!.
This problem has led me to order extended and knurled fuel screws to make life easier.
Ive checked for vacuum leaks by spraying carb cleaner, all seems fine.
The floats have also been set following 'Clear tube' methods and carbs cleaned.
The valves have been adjusted.
All these problems remain even after performing the above steps so i can only think it is related to jetting.
I would also like to know, when checking fuel/float level on the carb via clear tube, if fuel level in the tube remains at a certain level can this be used as an indicator that the needle and seats are fine and fit for purpose?

Appreciate if anyone can help.
I would start with by dismantling and do a good cleaning of the carbs internals and jets, and take a note of the size of the jets for future reference, and if the pilots are 22.5s, change them too 25s............
 

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Discussion Starter · #3 ·
I would start with by dismantling and do a good cleaning of the carbs internals and jets, and take a note of the size of the jets for future reference, and if the pilots are 22.5s, change them too 25s............
Willy. The carbs have already been cleaned and I've ordered vitos jet kit with the fuel screws for easy future adjustments.
I've not checked jet sizes, needle clip positions etc, as of yet.
I will take a look at the jet sizes etc for you once I receive the kit.
Could you let me know what the specs of the jets etc should be for a stock Raptor 660.
Also what's the reason for bigger pilots?.
 

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Master of the Electron
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Your pilot jets are still plugged - causing poor idle and popping on decel - did you rod them out with wire when cleaning? Bet not.

Stock pilot jets have always been a bit lean (22.5). 25's take care of it.

Stock mains are 140L/145R.
 

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Discussion Starter · #5 ·
Your pilot jets are still plugged - causing poor idle and popping on decel - did you rod them out with wire when cleaning? Bet not.

Stock pilot jets have always been a bit lean (22.5). 25's take care of it.

Stock mains are 140L/145R.
I knew I should of done this whilst cleaning but didn't know if jets had to be turned a certain number of times or not so never bothered.
So about the plug being black.
What's the likely cause of that then if your saying it's lean on pilots, a bit confused?.
Is it due to maybe the mains and/or jet needle being rich?.
About the needle and seats in the carb, by monitoring the level of fuel via clear tube, if the level remains at set level can this be used as an indication that the needles/seats are fine?. Just asking as my reservoir has overflowed before but not rode properly since oil change and hope it doesn't occur again.
Float levels has been corrected using 'clear tube' method.

Thanks for your time.
 

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I am unique
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Willy. The carbs have already been cleaned and I've ordered vitos jet kit with the fuel screws for easy future adjustments.
I've not checked jet sizes, needle clip positions etc, as of yet.
I will take a look at the jet sizes etc for you once I receive the kit.
Could you let me know what the specs of the jets etc should be for a stock Raptor 660.
Also what's the reason for bigger pilots?.

The reason I suggested the bigger pilots is because of your problem............22.5 have never been big enough and a slight amount of contamination in them makes it worse.............
A black looking sparkplug is not a good indicator that it is running rich, UNLESS you just drove in high gear for a mile at wide open throttle with a hot engine and held it a sustained high speed without hitting the rev limiter, Then turned off the ignition, allowed the engine to stop by pulling in the clutch as fast as possible, and then closed the throttle, you can then do an accurate plug check...............
Black sparkplugs can be caused by rich fuel mixtures, poor fuel, misfires, overly lean condition, improper timing, etc................
 

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Discussion Starter · #7 ·
Right. I'm just waiting for my new pilots etc to come through and ill let you know what the outcome of this is once fitted?.
About the needle/seats, any suggestions for checkIng for leaks. My reservoir has over flowed previously but carbs don't leak from overflow tubes and there is no gas present in airbox/filter.
 
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