Tuning Anyone running 500/650 at elevation???
- Thread starter jtrashy
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Tuning Anyone running 500/650 at elevation???
I'm at 6,000+ feet and haven't re-jetted my carb in my 500F with a 126 650cc engine. It runs fine.
After messing around with the jets in my 850 with little noticeable difference in routine driving, I haven't bothered with my 500 (yet). I do need to keep my idle adjustment screw open pretty far, so I guess that's evidence that re-jetting might make a difference.
I'll be very interested in what you learn.
After messing around with the jets in my 850 with little noticeable difference in routine driving, I haven't bothered with my 500 (yet). I do need to keep my idle adjustment screw open pretty far, so I guess that's evidence that re-jetting might make a difference.
I'll be very interested in what you learn.
Did you keep the timing the same also? Are your running 28’ at 3000 rpm?
the hobbler
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Justin; I have spoken to my "Weber" man again and he has suggested that you knock the timing back a little bit---try 8 BTDC at idle and 25 BTDC at 3,000rpm.
I just checked, and I'm afraid I don't have any notes on where I set the timing. Anyway, given the worn condition of the engine and carb, setting timing is not an exercise in precision for me.
Idling pretty good now. I backed out the idle adjustment all the way out and set timing to 8/25 like Hobbler suggested above. Combo of both did the trick.
My 650 feels like a 500 now, not sure how much of that is lost HP from elevation. It skips a beat here and there so I’ll have to figure that out.
My 650 feels like a 500 now, not sure how much of that is lost HP from elevation. It skips a beat here and there so I’ll have to figure that out.
I went back and looked at my notes from a few years ago about re-jetting my 850. Here is a helpful guide I found at the time:
https://lcengineering.com/tuning-weber-carbs-for-high-altitude/
After some experimentation, I did end up using idle and main jets that are a couple of sizes smaller than the factory jets. I did not find any improvement from increasing the size of the air bleed jets, so I reverted back to normal.
(All of this was done using ear and butt meters. No actual measurements involved.)
https://lcengineering.com/tuning-weber-carbs-for-high-altitude/
After some experimentation, I did end up using idle and main jets that are a couple of sizes smaller than the factory jets. I did not find any improvement from increasing the size of the air bleed jets, so I reverted back to normal.
(All of this was done using ear and butt meters. No actual measurements involved.)
