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2strokes4u

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So i have a drag bike and gearing is 17/38. Pulls hard through 1st 2nd, 3rd, and mid way through 4th it stop pulling as hard and then picks back up into fifth. I was thinking jetting but then i thought that full throttle the entire time so main jet should not be the issue cause it would have lagged out the gate. I am not shifting to fast cause it hits 4th and pulls then half way you can feel the pull lighten up and come back. 

 

Cub is not ported, i am running shearers, fresh plugs, running 38 pwk so should be plenty of fuel for motor, wires were new as of nov 2012 but only about 2-3 hrs on bike. I am thinking porting will fix issue but just wanted to make sure there isnt something else i am missing that could be a quick fix. Another rider rode and felt the same thing as I did. 

 

Please provide thoughts

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i think there is only one nut on each arm bolt.I have not measured the weight though. I have not tuned lockup at all. it snatched clutch right from your hand from the gate though. 

 

I will do a plug chop to make sure thats not an issue. its warmer outside and I went down on my main from 178 to 175. 178 was pulling hard in 40-50 degree weather. now its like 75-80. I left my dremel in KC and have no way to cut plug though

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and i dont have billet bowls....just dual pingle. might be running out of fuel around 4th gear. i do have a lil leak around pingle as well. think builder forgot to put teflon tape. could this effect the gravity feed or something? Just asking

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If it was fuel it wouldnt recover more than likely. when they starve out they fall flat and run real shitty. my initial thought was not enough arm weight as well but wasnt sure if it would recover as well. i guess with the added rpm from 5th gear it might add enough force to lock back up.

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If you run a bowl dry it will often times cause it to backfire, burn a plug off and as fast as your motor is turning on asphalt motor damage almost immediately unless you let out very quickly. Doesnt really sound like that in your case but possibly. One side will often show a slightly different tune and its probably your left side. It very well could be that you need to shift it because you are running out of useable rpms. I have burned up a pisron in gas bike with pwks and not having billet bowls running on the street for less than an 1/8 mile. Where do you ride/race in KC? I am about 20 miles from KC.

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my bike is in NC. Thats where I do my racing. The temperature was around 77-80 degrees that day it was pulling back a little. the next day it was 60 degrees and the motor pulled through all gears. It seems to have been a main jet issue. more air getting sucked in on the cooler day which made it run a lot stronger down low and up top. 

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