Lectrons vs. PWK For Methanol
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Good thread Dave.
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Indeed, a good thread. Not much posting though.
I have my preferences in carbs, just like most everybody else does.
My preferences are based on comfort with a particular carb and understanding the jetting circuitry more than they are performance based.
I personally like PWK series carbs, mostly because that's the carb I started with on a mildly built engine. It took some time to come to grips with the different jetting circuits, but I think I understand them fairly well now.
The only one to ever post a dyno chart showing the two carbs compared back to back that I'm aware of is More-Torque. I don't think the two carbs were the same size however, with the Lectron being bigger.
Here's my take on the two carbs:
Lectron:
+ simple but effective carb
+ fewer jetting circuits, and thus easier to jet
- having fewer jetting circuits can also make it harder to jet in certain throttle postions/rpm ranges
PWK
+ more jetting circuits make jetting in the whole rpm / throttle position spectrum easier.
- the above statement also makes it a more complex carb and more things to change.....
+ a multitude of jetting possibilities exist with the availability of the needle jets, as well as the mains and pilots (sudco.com)
+ effective carb, but somewhat more complex.
I don't know which one makes more power, though, when apples to apples are compared.
I have my preferences in carbs, just like most everybody else does.
My preferences are based on comfort with a particular carb and understanding the jetting circuitry more than they are performance based.
I personally like PWK series carbs, mostly because that's the carb I started with on a mildly built engine. It took some time to come to grips with the different jetting circuits, but I think I understand them fairly well now.
The only one to ever post a dyno chart showing the two carbs compared back to back that I'm aware of is More-Torque. I don't think the two carbs were the same size however, with the Lectron being bigger.
Here's my take on the two carbs:
Lectron:
+ simple but effective carb
+ fewer jetting circuits, and thus easier to jet
- having fewer jetting circuits can also make it harder to jet in certain throttle postions/rpm ranges
PWK
+ more jetting circuits make jetting in the whole rpm / throttle position spectrum easier.
- the above statement also makes it a more complex carb and more things to change.....
+ a multitude of jetting possibilities exist with the availability of the needle jets, as well as the mains and pilots (sudco.com)
+ effective carb, but somewhat more complex.
I don't know which one makes more power, though, when apples to apples are compared.
I use mikunis although the people I know that use the lectrons say they love them..I for one have not touched one nor do I know anything about tuning one so I would say naa Ill pick the mikunis over the lectrons but basically its like working on a motor chevy/ford Its really just what you are used to I think.
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3,418 Posts
Having run both with a fuel pump for alky, here's my take.
39PWKs:
Good:
Run of the mil, very common, parts easier to get, separate jetting circuits. CHEAPER.
Bad:
More circuits to jet (half empty/half full..
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), dump fuel to change pilots or mains (remove bowl)
41.3 Packard Lectrons
Pros.
Simple. Easier/less adjustments. No need to remove the bowls unless you want to clean or change needle seat (gravity to fuel pump, etc. or to set floats). Remove 3 screws to twist and adjust the metering rod for off idle to mid range, twist the PJ for top end. No jets to buy. Less finicky about temp changes for methanol. Can be converted from gas to methanol with a simple switch of the metering rod, and back to gas just as easy.
Cons.
Expensive. Non conventional compared to Mikuni and Keihin. The correct metering rod is 100% critical to get these to work. Need new throttle cable for the bigger carbs (Stock worked fine on my 39's, it would not open my Lectrons all the way and I have an aftermarket throttle). Needles are 35 bucks each or so...roughly. Less circuits to tune (Again, half full/half empty)
I ran my 39 PWKs almost all year. I received Lectrons at the end of the season, and the ONLY thing I changed was carbs.
I felt like I was going slower on the track, but my ETs improved and were much more consistent with the Lectrons. The bike was smoother in the middle RPMs...so it felt slower, although it was going faster.
These carbs were given to me, ran once...and setup for a 10 mil twister for 1/8 mile. So...I had to lean it out just a hair. I called Dennis Packard to see about the needle, he said it will work. Don't drill the carb, don't touch it. Told me how to fine tune the metering rod (same as camatv and another user told me, word for word)
I hit the lotto jackpot with these babies, I know they retail for 700 to 800 bucks, money I would've never spent on carbs alone. I just got lucky....
Fine print would be this. Do I feel I"m missing out on anything compared to my 39's, ET wise, etc? Not really...to be honest.
But I like the simplicity and ease of tuning on these carbs. to be honest, once they're set....they're pretty much set. I leaned out the needle/metering rod half a turn to go from racing the ice at 660' feet to 300 foot of sand down at Gilbert. that's all I changed.
If money is not an issue, or if you get a set for a fair price, get them. You'll love them. But I strongly suggest discussing your setup with a known Lectron Specialist, namely Packard or Fast by Gast.
39PWKs:
Good:
Run of the mil, very common, parts easier to get, separate jetting circuits. CHEAPER.
Bad:
More circuits to jet (half empty/half full..
41.3 Packard Lectrons
Pros.
Simple. Easier/less adjustments. No need to remove the bowls unless you want to clean or change needle seat (gravity to fuel pump, etc. or to set floats). Remove 3 screws to twist and adjust the metering rod for off idle to mid range, twist the PJ for top end. No jets to buy. Less finicky about temp changes for methanol. Can be converted from gas to methanol with a simple switch of the metering rod, and back to gas just as easy.
Cons.
Expensive. Non conventional compared to Mikuni and Keihin. The correct metering rod is 100% critical to get these to work. Need new throttle cable for the bigger carbs (Stock worked fine on my 39's, it would not open my Lectrons all the way and I have an aftermarket throttle). Needles are 35 bucks each or so...roughly. Less circuits to tune (Again, half full/half empty)
I ran my 39 PWKs almost all year. I received Lectrons at the end of the season, and the ONLY thing I changed was carbs.
I felt like I was going slower on the track, but my ETs improved and were much more consistent with the Lectrons. The bike was smoother in the middle RPMs...so it felt slower, although it was going faster.
These carbs were given to me, ran once...and setup for a 10 mil twister for 1/8 mile. So...I had to lean it out just a hair. I called Dennis Packard to see about the needle, he said it will work. Don't drill the carb, don't touch it. Told me how to fine tune the metering rod (same as camatv and another user told me, word for word)
I hit the lotto jackpot with these babies, I know they retail for 700 to 800 bucks, money I would've never spent on carbs alone. I just got lucky....
Fine print would be this. Do I feel I"m missing out on anything compared to my 39's, ET wise, etc? Not really...to be honest.
But I like the simplicity and ease of tuning on these carbs. to be honest, once they're set....they're pretty much set. I leaned out the needle/metering rod half a turn to go from racing the ice at 660' feet to 300 foot of sand down at Gilbert. that's all I changed.
If money is not an issue, or if you get a set for a fair price, get them. You'll love them. But I strongly suggest discussing your setup with a known Lectron Specialist, namely Packard or Fast by Gast.
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288 Posts
be cool if kehien made a 45 or 48. their standard sizes dont cut the mustard on big singles.
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I think there is a Mikuni VM44mm carb. Its a roundslide though. And you could get it bored, maybe? Probably to a 46mm. I think there is a guy on QHQ that runs one on his alky lt500 bike. Carzzaco500 i think his name is.
Lectrons are great until they start overflowing then you will pull your hair out trying to get them to stop. Usually they are fine while you warm the bike up at the trailer but start overflowing as soon as you start to pull to the starting line lol. Both carbs work fine its just personal preferance in my opinion. Strangly some of the fastest big twins and triples in the country run the 39 keheins.
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This is going to sound bad, but I tune whatever I have to work with LOL...
But if I had my choice, it would be
For alky: (1)Lectron, (2)Mikuni, (3)Keihin.
For gas I would take any of them
I only dislike the Keihins simply for the fact that the dump tubes are not replaceable. Once they get worn out, especially on gas you simply have no choice but to toss them, if you want to tune the bike correctly. The Mikunis give the ability to infinitely change the needle/tube combo's and the Lectrons pretty much the same way. If you have the right needle to start with then it's wayyyy too easy. The simplicity of Lectrons makes guys overlook the easy way and overthink it.
But if I had my choice, it would be
For alky: (1)Lectron, (2)Mikuni, (3)Keihin.
For gas I would take any of them
I only dislike the Keihins simply for the fact that the dump tubes are not replaceable. Once they get worn out, especially on gas you simply have no choice but to toss them, if you want to tune the bike correctly. The Mikunis give the ability to infinitely change the needle/tube combo's and the Lectrons pretty much the same way. If you have the right needle to start with then it's wayyyy too easy. The simplicity of Lectrons makes guys overlook the easy way and overthink it.
You can bore the 44's to a 46 I have a 46 setup for alky they can do them to 48 also but takes alot of work
Get rid of the pump. That's what I had to do.
There is a guy that makes dump tubes for Keihns now.
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As far as I know, no one sells the brass parts that are in that piece. There is a cat on PS that claims he has made some up and will replace them for you. I have a set of 39s that I was going to do. However, I only have his info in a PM on PS and they are down...
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3,418 Posts
The first year I had my lectrons, no issues with fuel overflowing.
I've heard 10 different things about stopping that...
fouledout said don't store the carbs with fuel in them, or maybe it was methanol...the floats act like a sponge over time and need to be dried out.
After that first year, no matter what level I set the floats at...they'd overflow...
Not in the garage or on the trailer, but after a pass or two...luckily the overflow tubes are still on mine, so I don't fill my cases.
I switched to the smaller pump (35L per hour instead of 65L per hour) and a longer pulse line. Much better but not perfect.
When I get a drag tank...one of these years, I'll probably switch it to gravity feed and a dual pingle...and just leave the billet bowls.
I've heard 10 different things about stopping that...
fouledout said don't store the carbs with fuel in them, or maybe it was methanol...the floats act like a sponge over time and need to be dried out.
After that first year, no matter what level I set the floats at...they'd overflow...
Not in the garage or on the trailer, but after a pass or two...luckily the overflow tubes are still on mine, so I don't fill my cases.
I switched to the smaller pump (35L per hour instead of 65L per hour) and a longer pulse line. Much better but not perfect.
When I get a drag tank...one of these years, I'll probably switch it to gravity feed and a dual pingle...and just leave the billet bowls.
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