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Discussion Starter · #1 ·
Hello all, just wanted to introduce for my first post and let ya know what i just picked up. snagged a 2002 660 for a fairly decent price off of a friend of mine that had a couple minor issues like waterpump is leaking and gas was just dumping out of the overflow tube when fuel was on.

first thing i took care of was the gas issue, the right needle valve was stuck open and just dumping into the bowls, after cleaning it i noticed it had a couple nicks in it but seemed to be working ok, also had to re-adjust the floats but fixed my problem, i did order a rebuild kit for the carbs but just havent torn into it yet.
one thing i noticed that baffled me was the main jets, one was a 145 and the other was a 165..... from all the research i did i could not find anybody runnin this combo so i know i need to re-jet also. i really wish i would have seen what the pilot jets were. funny thing is it starts right up and seems to run fine.

new waterpump and engine ice is to be installed hopefully this weekend to take care of my second problem, probably could have just rebuilt the waterpump but took the easier way out.

it has a K&N drop in filter in the stock air box and had a gyt-r full exhaust on it, i replaced the pipe with an hmf performance series with the quiet core being that the previous owner to my buddy gutted the pipe.

i guess my first question is one that has been asked a thousand times, what jets should i start with. my set-up is:
600ft asl
full hmf exhaust
K&N filter/unmodded airbox

i was guessing at starting with #25 pilots and 150/155 or 155/160

how many posts before i can get pix of this beast up for you guys
 

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I am unique
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Hello all, just wanted to introduce for my first post and let ya know what i just picked up. snagged a 2002 660 for a fairly decent price off of a friend of mine that had a couple minor issues like waterpump is leaking and gas was just dumping out of the overflow tube when fuel was on.

first thing i took care of was the gas issue, the right needle valve was stuck open and just dumping into the bowls, after cleaning it i noticed it had a couple nicks in it but seemed to be working ok, also had to re-adjust the floats but fixed my problem, i did order a rebuild kit for the carbs but just havent torn into it yet.
one thing i noticed that baffled me was the main jets, one was a 145 and the other was a 165..... from all the research i did i could not find anybody runnin this combo so i know i need to re-jet also. i really wish i would have seen what the pilot jets were. funny thing is it starts right up and seems to run fine.

new waterpump and engine ice is to be installed hopefully this weekend to take care of my second problem, probably could have just rebuilt the waterpump but took the easier way out.

it has a K&N drop in filter in the stock air box and had a gyt-r full exhaust on it, i replaced the pipe with an hmf performance series with the quiet core being that the previous owner to my buddy gutted the pipe.

i guess my first question is one that has been asked a thousand times, what jets should i start with. my set-up is:
600ft asl
full hmf exhaust
K&N filter/unmodded airbox

i was guessing at starting with #25 pilots and 150/155 or 155/160

how many posts before i can get pix of this beast up for you guys
As long as the airbox is totally stock with the snorkel on and unmodified, you can run #25 pilots, stock needles and mains around 145 to 150 with the larger main on the right carb.........
 

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Discussion Starter · #4 ·
As long as the airbox is totally stock with the snorkel on and unmodified, you can run #25 pilots, stock needles and mains around 145 to 150 with the larger main on the right carb.........
you dont think i should start with the 150/155 as recommended on hmf's site for full exhaust. and as far as i know the airbox is un-modified
 

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Dude you can try whatever you want. Its trial and error. He was just giving you a good place to start.
 

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Discussion Starter · #6 ·
i understand that, and i can see he knows what he is talking about after reading several of his threads and posts. it was more or less i was asking why on his suggestion.

as far as the jetting thats in it now (145/165), what mods could call for that....it ran well this way but i know it was to rich, the pipe on it was completely gutted and had fuel comming out the end cap seams.

i know absolutley nothing about this quads past history
 

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There is no jetting that calls for that different of jetting.You just stagger the mains by 5 usually. As for what jetting to run you will not get any better advice then from Whilly. He is the Master with 660's here. Your not really opening the air to the motor up with the stock airbox lid and that is why you jetting don't go up much at all.

And Welcome to the forums.
 

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Discussion Starter · #8 ·
thanx for the welcoms guys, new to 4 wheelers and just wanna get it running good, i dont need alot of extra power or anything so i dont even know if ill end up modding the airbox ever but then again just like everything else there comes a point where you just want more so who knows
good starting point on screws? 2-1/2?
 

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I think the real question is - is your airbox COMPLETELY stock? Is the snorkel intact and not been 'reamed' out? If stock, go with Willy's suggestion... if modded a bit, go with hmf's. If modded significantly, go with 160L/165R.
 

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Discussion Starter · #11 ·
well, started to dig into it befor i left for work, it already had #25 pilots in it and also had aftermarket needles installed.

should i switch back to stock needles (if so 3rd clip setting) what spacers do i put under the clip? nylon and then metal.
or should i just leave aftermarket ones alone.

also my fuel mixture screws are stuck and heads are pretty stripped where i cant get a good bite with screwdriver.

ill be playing in the garage with it tonight when i get home
 

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The vitos jet kit comes with new air/fuel screws that you can turn by hand without a tool if your interested. Makes life alot easier. The heads on the screws on the bowls always strip out to. Its best to trade them out for allen head screws. You might be better off with stock needles if your running that rich. The mains need some attention for sure. If you switch back to stock needles i would start at the 3rd or 4th notch. Were are your needles set right now? You might just be able to lean them out by moving to a higher notch (lowering the needle). Good luck. =)
 

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Discussion Starter · #13 ·
the screws on the bowls are already switched to allen heads, i have new air/fuel screws that came with my rebuild kit, just gotta figure out how im gonna get the old ones out.

i know its not the best idea but i was thinking of just leaving them where they are and putting the other needles back in how they were.
 

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Discussion Starter · #14 ·
it ran good before, i just knew the jets were off by how big the differance between the 2 were, but the only issue i saw was it was dumping fuel through exhaust which told me to rich.
 

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Thats a good idea dude. If it was running good then maybe just fix your main jets like you said and see how it goes.
 

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Welcome to the forum! :)
 

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Discussion Starter · #17 ·
ok, i put the aftermarket needles back in but i dropped em one clip and i put 145/150 mains in her also. i did not mess with the fuel mixture screws being that they are still frozen.
she fires right up and idles nicely, as she is warming up i can crack the throttle with good response, but after it starts getting to normal tempature if i give it a quick throttle snap she slightly pops with a little flame out the pipe.

ideas and suggestions please
also can someone show me a pic of what the stock air lid looks like inside, it appears it may have had some tabs or something shaved off.
 

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Discussion Starter · #18 ·
put it back on third clip, still pops and backfires but i dont feel as much of a hesitation in the throttle.
well until someone chimes in im gonna go ahead and swap from 145/150 to hmfs recomendation of 150/155
 

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You probably need to adjust your air/fuel screws if its hesitating off idle. The mains are for 3/4 to full throttle. If you get it warmed up and let it idle for a few then shut it off and check your plug it should give you a good idea if it needs adjusting. If its helping when you move your needles then maybe you need to adjust them again. Its a pain in the ass i know. Im in the process of getting mine dialed in to. Trial and error. Just gotta be patient. Its worth it in the end, thats what i keep telling myself. =) before i had the head ported and polished, 11:1 piston, and cam i was running 22.5 pilots and it ran good. Im at 5000 elevation though.
 

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Discussion Starter · #20 ·
i did the switch on the mains to the 150/155 and its running a hell of alot better, i can carry the throttle all the way up with no problems, but if i snap the throttle quickly to WOT it will give me a slight hesitation at about half throttle mark....

where to go from here?
do i jump to 155/160 being that it improved greatly when i went up?
 
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