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Air fuel ratio?

29 Jun 2020 17:05
nick1993
Newbie
Newbie
Posts: 6
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Air fuel ratio? #1
Bought a 75 yamaha DT250. Ran great when i got it had 40:1 mixture ratio but it was suggested that i run 32:1. It smoked pretty bad and now it just kicks over and doesn't start. Ill be changing the plug and wire. But i did mess with the screws on the carb, and i was wondering if i put the screws all the way in, how many turns should i put the screws? I'm just confused because it ran great until i made the new fuel mixture and put it in. I Used Lucas Land and Sea s stroke oil. Made another post but forgot to include some info. Ill be replacing the plug, wire, and doing a fluid change. Any help is appreciated.

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29 Jun 2020 17:16
turbodan
Mini Enduro
Mini Enduro
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Air fuel ratio? #2
The difference between 32:1 and 40:1 is not significant enough to really affect fueling. 32:1 might be slightly smokier but with proper jetting you won't notice a difference.

Set the air screw at one and a half turns out and fine tune from there. The idle screw with the spring on it should be set where ever it needs to be to maintain appropriate idle.

I wouldn't mess with the plug wire just yet. Put a plug in it and see if you can get the carb sorted out.

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29 Jun 2020 17:31
nick1993
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Air fuel ratio? #3
Thanks really appreciate it. I'm new to this and any info is greatly appreciated.

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