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It's been running well the last 18,500 miles with stock jetting, air box and exhaust. Pulls good at all rpm's and gets about average fuel milage for an XS....but....
Few days back decided that just maybe Yamaha had to tune the XS on the lean side for EPA reasons. So cheapest way to "richen" it up was to raise the fuel level in the bowls, which I've done.
Had not re-sync carbs and it ran at about 85 percent of the power it had before changing float level (seat O the pants dyno)
This afternoon decided I run down to the shop and sync em.
Fired right up and as I was pulling away felt like it was not hitting on all four. Several things came to mind, pick-up coil wires?, more crud flowing out a the tank? ......well shop not that far a way so just rode it like it was.
Parked in front of the roll up and went around to get inside and open the shop. As the roll up opened I got a whiff of fuel. Walk over and sure enough.... got gas in the air box.
So it was going to turn into a carb cleaning too.
Got the air box off but could not tell which carb(s) were leaking.
So set petcocks to prime.....no leak....had a smoke and came back and still no leak. Stuck key in and fired it up and it, still was running ruff, bent over to look at the carbs and a steady stream of gas was flowing out of #4. WTF!?!
So checked compression...good, checked spark...good.
Pulled carbs and opened up number 4, looks as clean as when I’d just cleaned em. Opened up the rest and no problems to be found.
Put em back on the bike, left the air box off and fired it up. Ran just fine.
Reinstalled air box and sync’ed the carbs and rode home. Now seems to have the same power it had with stock float height. Didn’t wind it up past 6500 tho.
Did notice that some of the “ping/nock” has been diminished but is still there. Will run a few tanks thru it to check milage and also maybe a little enthusiastic riding to see how she preforms.
Right now it’s got 110 mains across the board. If not much difference in milage and power may reset floats to stock and go up one on the mains.
Anybody ever get fuel flowing back out of a carb only when its running?
mro
Few days back decided that just maybe Yamaha had to tune the XS on the lean side for EPA reasons. So cheapest way to "richen" it up was to raise the fuel level in the bowls, which I've done.
Had not re-sync carbs and it ran at about 85 percent of the power it had before changing float level (seat O the pants dyno)
This afternoon decided I run down to the shop and sync em.
Fired right up and as I was pulling away felt like it was not hitting on all four. Several things came to mind, pick-up coil wires?, more crud flowing out a the tank? ......well shop not that far a way so just rode it like it was.
Parked in front of the roll up and went around to get inside and open the shop. As the roll up opened I got a whiff of fuel. Walk over and sure enough.... got gas in the air box.
So it was going to turn into a carb cleaning too.
Got the air box off but could not tell which carb(s) were leaking.
So set petcocks to prime.....no leak....had a smoke and came back and still no leak. Stuck key in and fired it up and it, still was running ruff, bent over to look at the carbs and a steady stream of gas was flowing out of #4. WTF!?!
So checked compression...good, checked spark...good.
Pulled carbs and opened up number 4, looks as clean as when I’d just cleaned em. Opened up the rest and no problems to be found.
Put em back on the bike, left the air box off and fired it up. Ran just fine.
Reinstalled air box and sync’ed the carbs and rode home. Now seems to have the same power it had with stock float height. Didn’t wind it up past 6500 tho.
Did notice that some of the “ping/nock” has been diminished but is still there. Will run a few tanks thru it to check milage and also maybe a little enthusiastic riding to see how she preforms.
Right now it’s got 110 mains across the board. If not much difference in milage and power may reset floats to stock and go up one on the mains.
Anybody ever get fuel flowing back out of a carb only when its running?
mro
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