SR540J backfiring after carb cleaning - how do I lean it out?

G

goneballistic

New member
I got an SR540J from this older guy that was getting out of riding because of arthritis as part of a package deal a couple weeks ago. The Yamaha is a really clean and nice machine and has been rebuilt in the last 1100 miles and has a new clutch in it.

The first time we took it out it ran like crap. This was the shakedown run so I suspected dirty carb. I came home and pulled it and sure enough it was all gummy.

I cleaned it out really well and put it back in (man getting that thing in and out is a PITA). On the VMAX the airboxes move so the carbs just lift out. I had to pry this one in and out.

Anyway we took it out again and it ran really well this time, didn't need the choke on and no smoking. With one exception: it backfired a couple times. The first time, REALLY loud. My 12 year old was riding and it about blew him off the seat it scared him so bad .:muahaha:

Anyway, I assume I need to lean this out a little but I'm not sure the correct way to do it. Anyone know which screw to turn on the carb to lean it down?

I'm riding at 8000-10,000 feet in altitude if that helps.....
 
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a lean condition usually causes backfires i though???? the screw right on the tom of the carb is the one you need...do you take the top bolts from the airbox....can loosen and slide back a bit!
 
Did it Backfire through the Carb or out the pipe. Out the carb is either lean on fuel or timing problem. Out the pipe is bad plug.

Mark
 
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