240 4th gear stumble

bundyho1

New Member
Dec 29, 2007
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Rustburg,VA
14/40 gearing +6 timing 90 temp what would cause the blasters power to just fall off in the upper gears?You think the timing would play a roll in this?
 
yea mines in 4th and 5th wont go in the powerband it like falls in nuetral and revs so mayb our problems r the same
 
main is likely off esepcailly with high temps and humidity
what did you end up with ? whats the plug look like
 
Well the last jetting run was on a 70 temp day and less humid and it was a 152 main and it was running pretty strong.But today i had the same main in and it was about 90 out and more humid and it was running kind of flat .I didnt do another plug chop, i guess i need to.
 
Bundy, I've got almost the exact same mods as you. I'm running a 150 main in mine and its a little fat. Maybe try a 148 or 150 in yours
 
if it revs like your in neutral then when you back off the throttle and excel gradually and it doesn't do it it's most likely your clutch slipping. I had the same problem in the upper gears and replaced clutch plates and now it doesn't do it anymore.
 
I was gonna say for anything above 85 degrees I would retard the timing to say 5 or 4 1/2, colder weather you can advance the timing