Quote:
Originally Posted by Okierider
So question for the hive here-still learning about carb tuning.
Is there any harm to running a tad rich on the high end? I know gas mileage might suffer some but mechanically speaking what’s the worse that could happen?
My idle is pretty well tuned and my needle is in position 5 (bottom most setting). At steady 50% throttle, 7-8k rpm and hotter than hell ambient temps, the thing *just* starts to pop from running rich-all the way up accelerating to it, sounds fine and pulls great. It’s just rich enough to let you know you’re not running lean lol.
|
Running a bit rich is not a problem. Excessively too rich will cause bogging/misfire when you twist the throttle. If it is on the edge, you won't get full normal throttle response (minor misfiring). Ideally, try one step down on the jet. If it seems more powerful and the minor bogging goes away, better. Mechanically, running rich won't hurt your engine, but the piston head, cylinder head/valve surfaces (and spark plug) will get coated with unburnt fuel which looks like a black and sooty build up. This is obvious when you pull the plug and "read" the spark plug (black dry soot). If in doubt, you can try something different, but waiting and reading the plug is going to give you the answers.
Did you save your OEM carb? It is a smoothbore YouALL PE30, and mine came with 120 main and 40 pilot jets. Jet it 125/45, reinstall it, and see how that works. It's a good carburetor. We are probably at the same altitude (below 1000 feet). On my bike, this is just slightly rich on the top end, as well as first 1/4 throttle. I shimmed the needle ~1mm (one washer) and now that the weather is warm, I don't need choke. That is at least slightly rich jetting. I think it's OK though. I also experience very slight misfire at top end, but I am not sure, so I will run it for a couple of tanks and read the plug... I might need to back off to OEM main (back to OEM 120!), or possibly remove the shim. Without some testing and time, I won't know for sure, either way. This is the first bike I got that was jet OEM nearly perfect for 600-1000 feet elevation. It is really close, and it won't hurt the bike.
Running lean is not good, but that is not what you asked!