Maintenance & Technical > KX500 Original
Intermittent high rev on my '88 kx500
Polar-Bus:
KX500's all experience a small amount of rpm "surging" no matter weather your jetted ideal or slightly rich, so don't beat yourself up to try and rid the engine of surging. Inspect your plug after a long WOT plug chop run and that's about it.
bigbore:
--- Quote from: sandblaster on October 27, 2011, 03:22:16 AM ---Depending on the temperature I run a 58-62 pilot jet at sea level to 2000 ft.
The hotter it is outside the more mine tends to surge after riding for a bit and then idling.
Since my jetting is close to optimal when it does surge I just hit my kill switch for a second or two until the engine winds down, just enough not to kill it...
Also, depending on the temperature I run a 168-175 main jet and a stock needle at the 3rd position at the same altitude.
It's important to remember that surging is not pinging.
If it's pinging, it's time to worry... :roll:
--- End quote ---
im over in ireland and the temperature is always really low e.g. between 5-10 degrees celsius. i plan to get it as close to stock setting as possible. i understand it might not fully go away so im going to try the 55 pilot first and see how it goes with that.
i presume the reed spacer and boyesen power reeds i have wont require a different setup for the jets? since i fitted them the bike still runs the exact same just a little more low power but no affect on power delivery.
Polar-Bus:
--- Quote from: bigbore on October 27, 2011, 08:32:23 PM ---
--- Quote from: sandblaster on October 27, 2011, 03:22:16 AM ---Depending on the temperature I run a 58-62 pilot jet at sea level to 2000 ft.
The hotter it is outside the more mine tends to surge after riding for a bit and then idling.
Since my jetting is close to optimal when it does surge I just hit my kill switch for a second or two until the engine winds down, just enough not to kill it...
Also, depending on the temperature I run a 168-175 main jet and a stock needle at the 3rd position at the same altitude.
It's important to remember that surging is not pinging.
If it's pinging, it's time to worry... :roll:
--- End quote ---
im over in ireland and the temperature is always really low e.g. between 5-10 degrees celsius. i plan to get it as close to stock setting as possible. i understand it might not fully go away so im going to try the 55 pilot first and see how it goes with that.
i presume the reed spacer and boyesen power reeds i have wont require a different setup for the jets? since i fitted them the bike still runs the exact same just a little more low power but no affect on power delivery.
--- End quote ---
If your running in cooler temps then your 45 pilot is DEFINATELY too lean. Even my #52 is a tad lean in the cooler months...
bigbore:
--- Quote ---
If your running in cooler temps then your 45 pilot is DEFINATELY too lean. Even my #52 is a tad lean in the cooler months...
--- End quote ---
ah ok, i didnt realise the temperature affected it that much. yea the weather over here is crap always cold and raining!
Polar-Bus:
--- Quote from: bigbore on October 27, 2011, 10:35:45 PM ---
--- Quote ---
If your running in cooler temps then your 45 pilot is DEFINATELY too lean. Even my #52 is a tad lean in the cooler months...
--- End quote ---
ah ok, i didnt realise the temperature affected it that much. yea the weather over here is crap always cold and raining!
--- End quote ---
Generally speaking KX500's are low revving bikes, and if you're just a casuall weekend rider your low to mid range correct jetting selection is more critical than a desert rider who spends far more time 3/4 throttle and above (where the desert riders need to have proper main jet selection. Precise jetting takes some time to learn. It's the #1 question asked on the internet. It's very difficult to give a good answer. You eventually learn to use your "ear" as well as your "seat of the pants" when determining ideal jetting. The last tip I will give you is jet for a good running bike in all conditions that doesn't foul plugs. Don't attempt to jet lean for every last bit of hp, or there is a high probability that you will end up with a melted piston... I don'r claim to be a jetting "guru" but I do clearly understand jetting basics. My KX5 has a great jetting selection, but it took me severall tries to get there. I have a hot summer jetting setup, cooler "fall" weather jetting, and also a "winter" cold weather setup. I also make a practice to log all my jetting data so I can swap jets at a later time easily. I have awesome acceleration, and I never foul a plug even in extended riding in the woods. Do I have ideal peak hp ? I don't know and I don't care. I do know I have "safe" jetting and that more important to me (and my wallet :-D ) Good luck hope this all helps !
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