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Good question Chris.

These carbs weren't originally setup for my bike, they were setup for a twister motor for the 1/8 mile and a fuel pump.

When I called Dennis to talk to him about something else, we got into a 10 minute conversation about carbs (I told him I was a newbie but quick understudy...lol)

He mentioned a few things, like DO not drill the hole where the metering rod goes through, that he stacks a few washers under the seat (could be a sealing thing, not quite sure to be honest) etc.
 

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the holes just make it so the slide dont stick open ? never knew why they were there. the flat part of the needle goes toward the reeds ?
 

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I have some 44mm with PE1 needles on my 16 Mil Twister. Had them dialed in nearly perfect last year. I fixed several air leaks this year and now its way out of tune. Finally got it lean enough to leave, but I think its too lean. It almost hangs. On the flip side, the pjs start dumping alky in right off the bat and it's too rich there, but at the other end of the track, it doesn't need to go any leaner. How the hell do you tune that? If I lean the needle, it definitely lean hangs. If I lean the pj, it may melt down at the end. Is this where sanding the needle helps? That was only mentioned on the smaller carbs, though.
 

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raise the pj's height. if its up higher it wont start to pull till your wide open..



may take custom needles due to motor size/ configuartion.
 

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Call Dennis Packard.Smaller motors don't have the velocity across the venturi that larger motors do (less intake signal) so longer PJ tubes are used. And...it's safer.

A larger motor has a better intake signal and can pull fuel out of the PJ more easily....



I agree with what is said...but Dennis may have a different trick like a pilot jet in the line or something to cut down flow, etc.
 

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I have some 44mm with PE1 needles on my 16 Mil Twister. Had them dialed in nearly perfect last year. I fixed several air leaks this year and now its way out of tune. Finally got it lean enough to leave, but I think its too lean. It almost hangs. On the flip side, the pjs start dumping alky in right off the bat and it's too rich there, but at the other end of the track, it doesn't need to go any leaner. How the hell do you tune that? If I lean the needle, it definitely lean hangs. If I lean the pj, it may melt down at the end. Is this where sanding the needle helps? That was only mentioned on the smaller carbs, though.
Those big engines have in-excess of 1.5 primary compression, that raises the the mean pressure differential from 4560 Newton per square meter of a 1.25 primary compression engine to 9119 Newton per square meter at 1.5, the suction doubles every .25 of primary compression ratio.



Bigger carb's will slow down the intake velocity, 44's will need Lectron 17-2 metering rods set at 2.90 mills thick across the flats to start.
 

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thought it sounded like a needle issue..



if the PJ pickup is right in the middle of the bore of the carb with a correct needle it should work ok..



BUT i can be wrong also.. i would highly suggest calling denis on these OR lectron direct they have been in a process of reinventing themselves and trying to expand the lectron name again. for so long they have delt primarily with street bike motors and that field of racing..
 

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Well, I have a race to go to this weekend, so for now I will try to tune the Lectrons as is, and I have some Mikunis and PWKs to try.



What really makes me scratch my head is that it was tuned for the air leaks. I guess I could break some epoxy off of the cases and put those back
 

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What really makes me scratch my head is that it was tuned for the air leaks. I guess I could break some epoxy off of the cases and put those back


Yeah - do that .... or you could just achieve the same goal by drilling a hole in the side of the cylinder




There are "other ways" to reduce fuel flow - from capping the tank vent to filling the bowls with sand - lol
 

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Well, I got the carbs close. The fuel pump was the main problem. I tried 3 different pumps, but the problem was that it (the pump) was sucking air around the inline fuel filter, and the pump wouldn't stay primed up. I was trying to tune it for the false lean condition. When I fixed that problem, it was waaaayyy rich. I kept leaning it down until it would finally run down the track. The pjs ended up about 1/4 turn out and the needles are at (I think) 49.6 mm.
 

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Well, I got the carbs close. The fuel pump was the main problem. I tried 3 different pumps, but the problem was that it (the pump) was sucking air around the inline fuel filter, and the pump wouldn't stay primed up. I was trying to tune it for the false lean condition. When I fixed that problem, it was waaaayyy rich. I kept leaning it down until it would finally run down the track. The pjs ended up about 1/4 turn out and the needles are at (I think) 49.6 mm.


After you have a good base line with a good idle, measure the needle thickness across the bottom of the slides. On alcohol its about 2.9mm, that is the thickness of needle the carb will see when the slide's is closed. Set any new needle's to that thickness.



Any needle taper or length can be changed out without losing your base line tuneup. Changing from Packard trenched to Lectron 17,18,19 (L or XL) needles are simple. The same can be done on gas.
 

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I generally switch all of the PE-1 needles out for a lectron needle, I like the 18-19 range needles personally. I also like to have 2 powerjets with staggered tube lengths. IMO it is easier tuned and retains good fuel pickup on each tube. On anything bigger than a 40mm I keep the one fixed tube very short, I noticed FBG started doing that a couple of years ago. Alky carbs really dont need tuning in the 1/4-3/4 throttle range, just idle to part throttle, then WFO lol.
 
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