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I spent quite a bit of time in the last several days trying to conquer my low end hesitation. This occurred with the pod filter mod, and I have been wracking my brain since then, trying to get a good smooth running engine.
I was under the assumption that the airbox created a slicht vacuum condition, which would have aided in drawing fuel from the bowl at low rpm. I had figured with no airbox I would need to richen the low end to get a good run. Boy was I wrong.
I started by raising the needles a bit with a small washer. This made the problem MUCH worse. It would darn near die when I opened the throttle under load. woah. too rich, way too rich.
So I set the needles back to stock. This is an 81, so they really only have one position. Then I looked into other causes for a rich low end.
My tuning guide said the next step is float levels. Mine were already set at stock measurement and I had previously lowered them a millimeter and also raised them a milimeter. Since the needles told me I was WAY rich, I decided to lower the float level by three milimeters. WOW! there's the problem. the dead spot has nearly disappeared, and after a few more tweaks, it is smooth.
After getting that sorted, I found it to be running lean in the upper ranges, so I put bigger main jets in. From 110 or 112.5 to 117.5. I think I still need a bump up in size. I will pick up some 120s tonight.
My next problem is idle. I cant get it to go rich enough on the pilot screws to make it stumble, so I am guessing my pilot jets need a size bigger. I was always taught to run carb idle on the rich side, just lean of stumbling. That was on cars though, I'll see how well it works on the XS.
So far, I am guessing I have dropped the float levels close to 4mm. I would have never thought to move them that much. When I get them all sorted, I will post my final jet sizes and float measurements. Hopefully it will help someone some day. I know there is a tech tip recommending generic sizing for different combos, but so far mine has not followed suit.
I was under the assumption that the airbox created a slicht vacuum condition, which would have aided in drawing fuel from the bowl at low rpm. I had figured with no airbox I would need to richen the low end to get a good run. Boy was I wrong.
I started by raising the needles a bit with a small washer. This made the problem MUCH worse. It would darn near die when I opened the throttle under load. woah. too rich, way too rich.
So I set the needles back to stock. This is an 81, so they really only have one position. Then I looked into other causes for a rich low end.
My tuning guide said the next step is float levels. Mine were already set at stock measurement and I had previously lowered them a millimeter and also raised them a milimeter. Since the needles told me I was WAY rich, I decided to lower the float level by three milimeters. WOW! there's the problem. the dead spot has nearly disappeared, and after a few more tweaks, it is smooth.
After getting that sorted, I found it to be running lean in the upper ranges, so I put bigger main jets in. From 110 or 112.5 to 117.5. I think I still need a bump up in size. I will pick up some 120s tonight.
My next problem is idle. I cant get it to go rich enough on the pilot screws to make it stumble, so I am guessing my pilot jets need a size bigger. I was always taught to run carb idle on the rich side, just lean of stumbling. That was on cars though, I'll see how well it works on the XS.
So far, I am guessing I have dropped the float levels close to 4mm. I would have never thought to move them that much. When I get them all sorted, I will post my final jet sizes and float measurements. Hopefully it will help someone some day. I know there is a tech tip recommending generic sizing for different combos, but so far mine has not followed suit.
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