Originally Posted by
NitroAmmo
I'm having a problem tuning the top end of the GRP Tuned. The thing takes off like a rocket, but it gets to what feels like mid range and never pulls out the high end. I tried adjusting the HSN but the temps seems to get too high, over 230. Any suggestions?
Try taking the motor back to factory needle settings
HSN=3.5 turns out from bottom
LSN=6.25 turns out from bottom
IDLE SCREW= 1-1.5 mm depending on where the lsn is set
Leave the top end alone and lean the lsn small hour turns at a time till you have good smoke and good punch off the bottom. If you need a little more on top just lean the hsn a small turn or 2. Keep in mind if you tune it and run up and down the street 2 times you haven't given the motor a chance to balance out. Meaning before you decide you need to crack the screws anymore give it a chance to catch up 10-15 laps on the track or 20 passes up and down the street. Its really easy to get these motors to lean because it takes a minute for the needle turn to really grab hold. Other than that check the usual suspects. Fuel tank filter fuel line carb boot and o-rings on the carb.