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Discussion Starter · #1 ·
Hello can someone please explain to me how the Raptor 660r carb works? i'm not familiar with the setup. I can see that one is a secondary, and one is the main. Also if the carb has been jetted do the air mixture screws need to be readjusted? If so does the secondary and main need to be readjusted and set at the same level? I am not sure what size jets have been put into the machine. I just know that is has been jetted.
 

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Hello can someone please explain to me how the Raptor 660r carb works? i'm not familiar with the setup. I can see that one is a secondary, and one is the main. Also if the carb has been jetted do the air mixture screws need to be readjusted? If so does the secondary and main need to be readjusted and set at the same level? I am not sure what size jets have been put into the machine. I just know that is has been jetted.
This is not a main/secondary carb setup. This is a dual carb setup. Yes, your A/F mixture screws will need to be adjusted when you rejet. In order to find out the jet sizes you will need to take the carbs off and remove the jets. Each jet will have a number on them which tells you the size.
 

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Master of the Electron
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The Raptor has three intake valves and the intake manifold is set up such that one side actually flows a bit more than the other... both carbs are always in full use, they are not a primary/secondary.

SO, stock mains are 140 left and 145 right to match the minor difference in air flow (at WOT). Because air flow is much closer to equal at lower throttle positions, both needle setting (for 1/4 to 3/4 throttle) and pilot jet/fuel screw settings (for idle to 1/4 throttle) are usually set the same on both carbs.

Jet selection is wholly dependent upon what mods have been done to the engine vis-a-vis flow through the engine - if you add a freer flowing exhaust, expect to raise the main jet numbers by around 5-10 each... if you also open up the airbox, add another 10 each.

SO, with free flow exhaust and open airbox, expect to need around 160L/165R mains and 25 pilots. Also, aftermarket needles are necessary for their more aggressive taper... then all get tweaked to optimize.

Again, pilot jets and fuel screws control idle to 1/4 throttle, needles 1/4 to 3/4 throttle, and main jets 3/4 to wide open - so one adjusts accordingly - if you have a mid-throttle stumble, you adjust the needles...
 

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Discussion Starter · #4 ·
When I bought this a couple years ago it ran fine, so I'm guessing the set up with the Jets must be good, if it ran fine when I first got it. Jetted/White Brothers Exhaust/K&N no lid. And last summer it ran fine as well after the carb was cleaned, and my buddy readjusted the A/F screws. I did buy a moose carb kit for it last year gaskets/needle & seat. After these new pieces were added to it, it ran like crap, till my friend cleaned and readjusted the A/F screws (which I don't understand why he would have to readjust the A/F screws considering where it was set prior to that made it run fine, unless it has something to do with the needle and seat?). After he readjusted the A/F though it ran almost mint for the rest of the summer still a little lean but not really that noticeable. With that being said the wheeler should have run fine this summer as well correct (unless carb is dirty)... Well it's running really really lean right now, and my cousin adjusted the A/F mixture screws back to stock, and it didn't make any different in how the wheeler ran. Still sounded the same backfiring half throttle. Does that seem strange that there was no difference in how it ran? I'm just lost at this point and so isn't my cousin, because it ran so good the first year I got it, why do we need to keep readjusting the carb every summer. He has taken the carb out 3 times already cleaned it spotless, blew through all the jets multiple times, and put it back together. But still no progress still running lean.
 

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Master of the Electron
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Pilot jets are clogging up. Clean the carbs this time paying special attention to pilot jets and passages and fuel screws and passages - they all must come out and be cleaned individually... trust us!

To prevent a recurrence - when bike is going to sit for more than a day or two, close fuel petcock and idle engine with choke on until it dies. This drains most fuel from the float bowls and leaves all the fuel wetted jets dry. Fuel evaporating leaves varnish behind on these surfaces, gumming them up. No fuel, no varnish, no cleaning required!
 

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When I bought this a couple years ago it ran fine, so I'm guessing the set up with the Jets must be good, if it ran fine when I first got it. Jetted/White Brothers Exhaust/K&N no lid. And last summer it ran fine as well after the carb was cleaned, and my buddy readjusted the A/F screws. I did buy a moose carb kit for it last year gaskets/needle & seat. After these new pieces were added to it, it ran like crap, till my friend cleaned and readjusted the A/F screws (which I don't understand why he would have to readjust the A/F screws considering where it was set prior to that made it run fine, unless it has something to do with the needle and seat?). After he readjusted the A/F though it ran almost mint for the rest of the summer still a little lean but not really that noticeable. With that being said the wheeler should have run fine this summer as well correct (unless carb is dirty)... Well it's running really really lean right now, and my cousin adjusted the A/F mixture screws back to stock, and it didn't make any different in how the wheeler ran. Still sounded the same backfiring half throttle. Does that seem strange that there was no difference in how it ran? I'm just lost at this point and so isn't my cousin, because it ran so good the first year I got it, why do we need to keep readjusting the carb every summer. He has taken the carb out 3 times already cleaned it spotless, blew through all the jets multiple times, and put it back together. But still no progress still running lean.
Also, rather than blowing air through the jets, try running a piece of copper speaker wire through the jet passages. I'm surprised QM didn't suggest this, I first heard this from him.
 

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Master of the Electron
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Also, rather than blowing air through the jets, try running a piece of copper speaker wire through the jet passages. I'm surprised QM didn't suggest this, I first heard this from him.
I really get tired of repeating the same old thing that anybody could find if they just read through a few threads and/or searched for their problem. Thanks for bringing it up, cdg.

Yes, use copper strands (like that stolen from a piece of speaker wire) to clean out the pilot jets, along with spray carb cleaner and air... clean, repeat, clean, repeat - until you can see a nice, cylindrical shaft of light coming through the tiny passages. Any grit or mis-shapen light means clean some more.
 
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