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falling on its face 39pwk on a 392 cub


hughmyron

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Well i ended up with 165 main jet its caramelish color after a 1/4 pass, tried a 52 pilot and i had to leave the air screw closed because it would drive funny. Now heres my main issue, if im lets say chillen well under the powerband in whatever gear and i just happen to go WOT it completely falls on its face and sounds like if you just turned it off. It only does this when i go WOT, if i creep into it it wont do it. I just got back from my friends house we were going to start riding and literally 10 secs down the block i go half throttle to pick up speed and the bike falls on its face and turned off and didn't turn back on, we tried to push start it, we checked it had spark. Does this sound like a needle position issue?

 

Im running right now 165 main jet, 60 pilot jet, and needle in 3rd position.

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What needle do you have in the carbs, did you check compression , that sounds lean for a drag ported cub close to sea level , I would check compression that will let you know if you burnt it down

 

 

Did you do a leakdown test 60 pilot is close to what my drag ported alky bike runs

 

 

Sounds like the needles might have been quite lean and the rest sounds like a burndown. I am sure the pull starting couldnt have helped it.

 

 

The needles that come with pwk 39s. What do you guys mean by a burn down? Pulled the plugs yesterday and checked the pistons for any signs of detonation pistons look great and brownish. Can still read the part numbers on em.

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