• Hi everyone,

    As you all know, Coffee (Dean) passed away a couple of years ago. I am Dean's ex-wife's husband and happen to have spent my career in tech. Over the years, I occasionally helped Dean with various tech issues.

    When he passed, I worked with his kids to gather the necessary credentials to keep this site running. Since then (and for however long they worked with Coffee), Woodschick and Dirtdame have been maintaining the site and covering the costs. Without their hard work and financial support, CafeHusky would have been lost.

    Over the past couple of weeks, I’ve been working to migrate the site to a free cloud compute instance so that Woodschick and Dirtdame no longer have to fund it. At the same time, I’ve updated the site to a current version of XenForo (the discussion software it runs on). The previous version was outdated and no longer supported.

    Unfortunately, the new software version doesn’t support importing the old site’s styles, so for now, you’ll see the XenForo default style. This may change over time.

    Coffee didn’t document the work he did on the site, so I’ve been digging through the old setup to understand how everything was running. There may still be things I’ve missed. One known issue is that email functionality is not yet working on the new site, but I hope to resolve this over time.

    Thanks for your patience and support!

Round two of the "other" carb types - Lectron

Motosportz

Motosportz

CH Sponsor
Staff member
Many have seen this monster thread and various user reviews of the APT carb.

http://www.cafehusky.com/threads/apt-smartcarb.28324/

My personal testing showed the APT to be no joke and an amazing carb. Now the Lecton is in my hands thanks to Vinduro for letting me check it out while he is laid up. I'll take some pix ASAP but this is a cool looking unit. Clear see through float bowl, Same looking flat metering rod, "Power jet" top end adjustment (screw adjustment).

I just pulled it out of the box and took a peep, will get more info tonight but here is the measurements for those concerned about fit.

Reed block side - 1.678" / 42.65mm

Air box bell - 2.377" / 60.39mm

Total length - 3.812" / 96.84mm

will post the stock TMX carb dims this afternoon.

Looks promising.

Kelly
 
Snapped some pix

Fuel inlet, Idle (big brass), clear bowl. Line from bottom of bowl goes to the the top of the carb and that spring right where the "T" is in Lectron is for the top end adjustment. It draws fuel from the bowl to add to what the Metering rod does.

IMG_2841-XL.jpg


Intake side. Metering rod seen here at the bottom of the slide (like a needle on a standard slide) Note Choke is on the wrong side for my application but it big and should still be pretty EZ to get to.

IMG_2839-XL.jpg


Here you can clearly see the pickup tube for the top end nozzle.

IMG_2838-XL.jpg
 
Is it going on your WB165?
Stupid question, lol.

Hopefully it will stack up well against the SmartCarb well.
 
So here is my take after investigating two of these metering rod carbs. These "metering rods" are basically taking the needle to the next level to cover all ranges. This in theory makes some sense as it does not change circuits and thus no crossover or some circuits not working well with others. The key seems to be that the metering rod needs to be behind the slide for draw and velocity I am guessing. The slides in the APT and Lectron are quite different. The APT is much thicker and has like two guillotines. The APT metering rod seemed larger (guess) and had a different looking nozzle. The APT does not have the high speed main jet adjustment the Lectron has (although it id not seem to need it either) So they both basically use a needle to cover everything from pilot to main on a standard carb. That said I would think the metering rod, slide, carb shape, etc would be very important. Also It seems like this design would need to be very load / draw dependent (like all vacuum fed carbs are) so that a wide range of needs are addressed. It all makes perfect sense to me and APT seemed to get it right. Oh, it seems this system wound me more water tolerant as it can draw it through instead of getting caught in a pilot or main. This to me is another semi large advantage as many times I have had to limp through or fix water in the carb issues. We will see if this earlier version of the idea already was there of the APT has some forward progress on this tech.

Oh, unfortunately all i will be able to do is put the carb on and blip the throttle as my shock is out for a rebuild. Will get rirst ride Friday if all goes well.
 
What size of carb, 36mm ?. and thanks so much for keeping us updated on your testing, Very Valuable information :notworthy: . . I trust your views so I will be sitting on the fence until the verdict out.
 
Idacurt said:
Awesome! maybe the rep from Smartcarb can tell us how they are different?
Click to expand...


Here is a response to the same question posted on another forum by Corey at APT.

Corey said:
... there’s no school like old school. You're right the similarities are many, however the distinction between the Lectron and the SmartCarb spans over 40 years of development and is the final design in the long line of Edmonston designed single circuit flat slide carburetors, including the Lake Injector, Pos a Fuel, Lectron, EI Blue Magnum, Quicksilver and AFT”.

The Lectron is widely recognized as a “drag race” carburetor because it works very well in applications where maximum power is desirable. Which it does well, what it does not do well is provide high signal to the metering rod throughout the whole range of throttle opening and therefore smooth throttling suffers, requiring many different venturi sizes (every 2mm) and has thus gained a reputation as not being very streetable. The reason: Throttle opening and closing is symmetrical in relation to the throttle bore area, which is more or less round. While there have been small improvements over the years with Lectrons, the SmartCarb has a patented variable venturi shape that concentrates and accelerates airflow past the base of the metering rod under all throttle opening positions. This shape provides an extremely high pickup signal to the metering rod in all conditions and is also specific to enhancing air/fuel flow balance in both two cycle and four cycle engines.

The SmartCarb automatically and immediately corrects air/fuel ratios for changes in air density and elevation. The operating principle between the SmartCarb altitude adjustment circuit and a dial a jet (what Lectron calls its Power Jet) is the same; static pressure in the venturi is directly communicated to the float bowl to adjust fuel driving pressures, and ideally fuel flow remains proportional to airflow. The difference is a dial a jet has only a limited number of manual settings and must be reset for large changes in barometric pressures and/or elevation. The dial a jet also has opportunity for flow reversion at very high speeds because it is directly exposed to the venturi via the signal tube. The SmartCarb vents the float bowl directly to a scoop isolated in the venturi away from any opportunity for flow reversion.
Click to expand...
 
Still looking for a dyno comparison between the Mikuni TMXX with Suzuki jet needle and RB divider plate mods (like mine) vs APt vs Lectron. Sorry, I'm an engineer, I need facts, not opinions before I spend a grand. :D
 
Interesting and informative post. I remember reading some of that over there. My first thoughts on the matter is the keyhole design and altitude compensation (none vented pressure changing bowl) are the main differences. Sounds like the Letron is an older generation roundbore and meter rod design and needs to be adjusted more. As for the keyhole shape the engineer in me thinks you could compensate for that with the meter rod cutout to correlate with the air volume regardless of shape. The APT might be smoother because the shape makes it ramp up quicker but you would think you could still design the rod to be right. Again I could be talking straight out my ass. Just tossing crap out there.

I just installed it and fired it up...
 
Motosportz said:
Interesting and informative post. I remember reading some of that over there. My first thoughts on the matter is the keyhole design and altitude compensation (none vented pressure changing bowl) are the main differences. Sounds like the Letron is an older generation roundbore and meter rod design and needs to be adjusted more. As for the keyhole shape the engineer in me thinks you could compensate for that with the meter rod cutout to correlate with the air volume regardless of shape. The APT might be smoother because the shape makes it ramp up quicker but you would think you could still design the rod to be right. Again I could be talking straight out my ass. Just tossing crap out there.

I just installed it and fired it up...
Click to expand...
:popcorn:!
 
CelticDude said:
Still looking for a dyno comparison between the Mikuni TMXX with Suzuki jet needle and RB divider plate mods (like mine) vs APt vs Lectron. Sorry, I'm an engineer, I need facts, not opinions before I spend a grand. :D
Click to expand...

Funny. I am also into high fi stereo (well kinda) and there is always the guys that have to measure sound and flat and those that buy because is sounds good to them. I'm a sound good, could care less how it measures. For me the carb is the same. I put it on and went wow, that works well. Took it off and went, man I wish that APT was back on there. I miss it. All I need to know. I ride for fun not numbers he he he I would not drop a grand on it. The stock carbs work great. The APT, to ME works better. How much that is worth to you is a personal decision. I have no horse in this race, someone else bought the carb and I knew nothing about it. I was an innocent bystander :>) I will never sell APT carbs, they don't even have a dealer program. I like the APT, it works. Completely unbiased opinion. Your mileage my vary.
 
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