Carb issue

1070 Views 7 Replies 3 Participants Last post by jfisher34, Sep 14, 2018

jfisher34

Discussion Starter · Sep 10, 2018

i put a new carb kit in my 85 trx250 fourtrax. the reason was because it was running really rough when i rev'd it and it had been sitting for years. That seemed to take care of that problem. Now though, even though it idles really nice, if i give it just the slightest amount of throttle and hold it there, it will start to sputter and miss and sometimes shut off. Do i have the air/fuel screw too rich on fuel possibly?

thanks

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jfisher34

Discussion Starter · #3 · Sep 10, 2018

It is the original carb I believe. Spark plug is brand new and i have only run it for several minutes. not sure that will show anything however there is some black smoke coming out when i rev it. that is the other reason i think the fuel might be rich??

if the screw is on the back side of the carb (away from the gas tank), does that control the air and not the fuel? so "out" would let more air and "in" would restrict air?

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jfisher34

Discussion Starter · #5 · Sep 10, 2018

i took the entire carb apart, cleaned it in a simpe green solution in an ultrasonic cleaner and then put an entire new kit in it with gaskets. You are right that it sits in front of the bowl now that i'm remembering. so it does control the fuel mixture not the air mixture...correct?

i started with 2.75 turns out (that is what the old one was) and then adjusted it to the highest rpm. i cant remember where that ended up.

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jfisher34

Discussion Starter · #8 · Sep 14, 2018

SamUK was right. after closer inspection, I ended up having the mixture screw set wrong. i put it back to 2.5 turns out and she is running much better. Thanks for the help.

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