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Raptor 660 carb adjustments??

3K views 24 replies 4 participants last post by  Sixpack577 
#1 ·
So I have a stock 01 raptor 660 with a full hmf exhaust I live at around 1600ft and am having trouble tuning the carbs I put 145 and 150 mikuni mains in and turned the fuel screw on the left carb 2 and a half turns and on the right turned 3 full turns but still had low end bog and out of nowhere doesn’t want to start at all HELP...
 
#5 ·
You richened the jets... why? At your elevation you're marginally rich with stock mains.
 
#8 ·
Typically, backfire on decel implies too lean in the pilot (idle) circuit. The common fix is turning the fuel screws out (CCW) 1/4 or so turn each.
 
#13 ·
Uh oh... shoulda told us that in the beginning! If they're eBay cheapies you better take em off and just clean and re-install the originals.
 
#18 ·
Is there anything sticking out or is it broke off flush?

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#20 ·
Couple options really. Google "screw extractor" and you will see several different styles. I prefer the type that come with a drill bit but thats simply my preference. Dont forget to get a t-handle for the extractor if you use that style

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#22 ·
Update: I rebuilt the old carb with brand new mains 145-150 pilots are 22.5 and a brand new seal on the bowl but I can’t seem to figure out why it doesn’t want to idle, I can get it to start up with choke then it’ll warm up and idle but will randomly die at idle as if it’s not getting enough gas but I’ve never had this problem with these same exact carb adjustments before
 
#24 ·
Where should I set my needle clip position to be a good baseline to adjust from right now when I took it out I saw that it was in 5th position from the top but everything I’ve ever seen says usually to be around the 3rd position because it seems like my quad runs rich as it’s a pain to start when it’s cold and the spark plug was pretty sooted up last I checked
 
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