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Old 01-24-2008, 02:47 AM   #1 (permalink)
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Fuji 488 needs carb tuning

I have a Fuji 488 motor. I need to figure out how to tune it properly to keep it from burning up. I'm running a DG one piece can-pipe combo, and no airbox. I will probably be running pod type filters on the carbs. Right now it's open carbs. Anyway, the stock carbs had 280 main jets. Whenever I tried to go wide open, it would pop back through the carb. I figured it was really lean. I replaced them with 310, and the popping at wide open disappeared for the most part. It now pulls very strong on the top. However, it bogs down when you slowly pull the throttle, you have to feather it to get it going. Anywhere above idle to 1/4 throttle, it works great.

Anybody have an idea? I'm thinking the air bleed screw and needle clip, but I don't know exactly what to change.

I just stuck new plugs in it. I will perform a plug check and post results here tomorrow.
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Old 01-24-2008, 06:04 AM   #2 (permalink)
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Let us know what you find. Try to turn the air bleeds 1/4 turn in, then out t osee if it changes.
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Old 01-24-2008, 09:11 PM   #3 (permalink)
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I checked the plugs. The insulator was a dry black, and the tip of the electrode was a tan brown. I'm running a little bit more oil than you normally would (premixing it rich) so that might be why the black. Haven't messed with the air bleeds yet, mostly just ragging around on it.
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Old 01-24-2008, 09:27 PM   #4 (permalink)
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i have the same motor in my sled, and the dealer told me the main jets were 220. I have the stock exhaust tho, and air screw was at 1 1/2 turns out but it seems to like 1 turn a lot more. I saw SEG mentioning the edelbrock uni sync carb tool and so i bought one and works great my sled hasn't ran better.
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Old 01-25-2008, 01:28 AM   #5 (permalink)
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i have the same motor in my sled, and the dealer told me the main jets were 220.
Dude, my dealer told me they were 180's stock, so I bought 190, 200 and 210's. Imagine my surprise when I open my carbs and the stock ones are 280 and I just spent 18 bucks on shit I can't use.
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Old 01-25-2008, 06:39 AM   #6 (permalink)
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you can always look it up yourself to be sure. I know my dealer is shady as all hell and was doing everything they could to talk me into bringing it in for "repair". I had 210s in mine but the chart on my airbox said 210 was for 30 degree weather and warmer. the funny thing is the air box said 230 stock main jets. Only reason i went with 220 is that website below told me they were stock as well so i went with them. Maybe they changed it at different years?

http://parts.polarisind.com/Assemblies.asp is a great website for polaris part lookups
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Old 01-25-2008, 01:08 PM   #7 (permalink)
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I'm unsure if you are talking about the sled in your sig, so here is a question for you:

488 Liquid or 488 Fan?
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Old 01-26-2008, 12:25 AM   #8 (permalink)
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488 Liquid
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Old 05-02-2008, 11:24 AM   #9 (permalink)
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without the airbox installed you need to jet alot richer. you still have all the symtoms of being lean. you may need to change the pilot, slide or needle jet if raising the needle doesn't work. try turning in the air screw first, then raise the needle.
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