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'01 800 XC Running lean

1334 Views 8 Replies 7 Participants Last post by  Sno-X-treme
I recently installed a set of Carbon Tech reeds and a boost bottle on my 800 and my plugs seem to show a lean condition. The HSP boost bottle instructions said to turn the mixture screws on the carbs out 1/2 a turn because the bottle would lean the mixture out at low RPM and I did that. I could just jet up a size (running stock 460 mains) but I would like to try to get to the real problem if there is one. Thanks for the help.
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Just put in a richer main, when you put in a boost bottle and change other stuff on your intake side, there is a chance it will lean out, which it seems to have done.

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Well i always though that if you turned the mixture screw out, it would lean out the mixture and if you screwed it in, it richened the mixture. Actually im pretty sure that this is the case. Well for a mikuni carb anyways. Im not sure which type of carbs you have though. If you seem to decide that the carb adjustment is correct, i would just pull the carbs and clean them. All that will cost you is a couple bottles of carb clean and some time, instead of an expensive engine. Is it possible that the instructions had a typo or that you may have read it wrong??? Anyone else have any ideas?

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nope, clockwise/in=leaner on Mikuni. The reason its lean because the mods increased air flow which = more power. Put in a larger main.

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How is your idle? I just installed a Sportech boost bottle on my XC700 (no reeds though) and can't get it to idle down. It wants to stay up around 3 grand. Also, do you now get a little backfire? I'm curious to find out what you get for results if you change mains. I feel I'm in your boat.
Thanks for the help. I would have just put the mains but I needed confirmation. BTW I cleaned the carbs out when I put the bottle and reeds in and the idle is high now, about 2200.
If you put in a richer main, you are going to have to add some oil along with adding gas. Also, if it seems to be running fine and low to high end seems smooth with no gas starvasion, i would try an oil pump adjustment first.

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snow-x is exactly right the further in u turn the screw the leaner the mixture. yamaha has for years called this a fuel enrichment screw. the only air ajustment you can do is change the air jet on the intake side of the carb.

Skrplyr23 why would you add more oil in combination with a larger main?

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