Lectron carbs

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jefft

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Price aside, are Lectron carbs the ultimate 650 carbs? Has anyone used them? Are they easy to install and tune? What intake boots do they use, throttle cable? I know they are pricey but I also know there is a lot of junk being sold on ebay. I recently bought what was advertised as 77 carbs on ebay and I really am thinking I recieved a bank of carbs with 2 seperate years someone passed off on me.
jefft
 
Hugh (Punkskalar) is a huge fan of the lectron carbs. He sells them too. I would get a set if I could aford them.
I know he is busy right now building stuff for his shop, so I would try to get ahold of him in a week.
 
Yea I know he's busy right now. I will try later his mail box full. I wonder if any other members are running them could chime in?
jefft
 
From what I understand these carbs are fairly easy to get dialed in. I thought I read that you don't have to switch out a bunch of main jets , pilot jets, needles, etc. to get them adjusted. Hoping Hugh can give some schooling on these when he gets a chance. What kind of carbs are these classified as? Lots of questions.



jefft
 
They do cost bigger $$$ - why not go with VM34's..??
Do you know how to tune a carb..?? Jetting is jetting if you do/dont know how to tune a VM series carb what makes you think you will be able to tune Lectrons. Not being disrespectful just trying to understand why....
 
jefft said:
Price aside, are Lectron carbs the ultimate 650 carbs? Has anyone used them? Are they easy to install and tune? What intake boots do they use, throttle cable? I know they are pricey but I also know there is a lot of junk being sold on ebay. I recently bought what was advertised as 77 carbs on ebay and I really am thinking I recieved a bank of carbs with 2 seperate years someone passed off on me.
jefft
Click to expand...

This article was written with running Lectrons on air cooled RD's that were being raced in mind, however it gives an insight into what a Lectron carb is and how you go about setting them up. It is a direct copy of the original article that was published on the following forum in the "Dale Alexander archives"

http://www.aircooled-rd.com/

I am only copying it out in full because the original web site doesn't make it very easy to provide a direct link to the article. Obviously credit for the article goes to the original author and I haven't verified any of the content, it's just an article I stumbled on yesterday while researching another matter relating to RD Yamaha's. Hope the following is interesting or useful in some way.

Tech: Lectron Carbs by Dale Alexander

Hi all! Been reading the current string about Lectron carbs and would like to fill out some info.

Over 20 years ago, I remember having a set of Lake "Fuel Injector" carbs on my Norton Commando 750. I believe this to be the precursors to the Lectron style carbs. The Lake carbs did not have a float system at all, just a fuel line to the bottom of the carb where the needle would be. I don't remember how the mixture was adjusted as I never did adjust it! Hey! I was only 16 at the time and not old and smart(assed) like I am now. The carbs didn't qualify for more than a calibrated piss as far as accuracy but as they were one of the first "smooth bore" designs out there, they flowed a lot of air so power went up, even if it was crude power at best. And they looked cool. Exotic. Had to work better if you know what I mean ; )

Posa carbs were a like design so I won't spend any time on them.

Lectron carbs were much the same as well but with two VERY important improvements: a float system ala Mikuni and a powerjet top end fuel supplement.

Nothing special about the float system. It was a natural progression to correct what Lectron saw was a weakness in the Lake type carb. It allowed precision in the float level. The Lake was prone to flooding and hard starting(duh!). The power valve was a new concept at the time and Lectron was the first carb I remember seeing with a power jet and should be note-worthy in that fact.

HOW LECTRONS WORK

The Lectrons have a central fuel outlet, that being the needle area. The needles controlled all fuel now with the exception of the power jet. One of the ideas was to eliminate the rich and lean spots in the fuel delivery curve as can happen with a multi-area delivery device such as a normal carb. The other was to make a system that was easy to adjust. Lectron succeeded brilliantly in one area, failed miserably in the other.

Fuel control was with the needle. A taper was ground into the needle on the side that faces the intake area of the engine. Needles were graded and marked 5-3, 6-1, 6-2 etc. These numbers were easy to understand. The first number was the overall richness of the needle. A 5 series was leaner than a 6 series. The second number was the midrange richness. A -3 was richer than a -1. The very top end was controlled by the power jet exactly as we understand power jet function now.

In order to have a "base" point that tuning could be initially set to, a distance was specified as standard, a datum. This was the length of the needle from the adjusting nut(what would be the needle clip in a Mikuni) and the tip of the needle that extends into what would be the needle jet in a Mik. The "needle jet" was not adjustable, much like the TMX style of Mik. The standard length was 1.945" or something like that. If the length was longer, the overall fuel was leaner as the taper would be lower and this would allow less fuel for any given throttle opening. The opposite was true if the needle length were shorter than 1.945". I think that if you had to go more than 2 turns in either direction, it was time to change the needle for a different fuel curve. This allowed for the fine adjustment of fuel.

If one were to replace the screws holding the top of the Lectron with snap clips to allow quick removal of the top, a minor needle adjustment with power jet swap could be made in about 2 minutes for 2 carbs. This was one of the Lectrons strong points.

If jetting was ok in the mid-range but off a bit just before power jet came on, you wouldn't want to adjust the needle as this would upset the balance with the mid-range. You would select a needle with a different second number - 1, -3 etc. THIS is where the Lectron failed. The quality control of the grinding of the needles was such that even though you had two needles marked the same, it didn't mean that you hade two needles that were the same. At first this caused all kinds of confusion as one would change the needles expecting a change in a known area and the engine wouldn't run anything like what was expected. Only after measuring the needles very accurately at absurdly small stations were we able to ferret out that Lectron needles were ground by the firm of "Byguess and Bygolly"!

The only way to solve this problem was to carefully hone stone the needles and hope that the results gave you a pair of needles that could be used together, run them, grade them, and hope that one was fortunate enough to get a selection after a while. With all this tuning work done to the needles, it's not hard to see that if one had a good set, they didn't get loaned out at all(Hey! I need as set of 6-2's. Got any I could borrow for this race?) Might as well part with your right arm once your friend figures out your needles work better than his!

On of the other strong points was that without a pilot circuit, the Lectrons could be run at absurd angles(35 deg) compaired to the Mik's. This allowed the carbs to be mounted to a straight manifold on the Super-street RD's for a more direct shot at the intake. If a Mikuni was mounted this way, it would flood horribly under hard braking as fuel poured out of the pilot circuit. This was not a problem with the central fuel point on the Lectron's.

But time moves on and the quality control finally caught up to Lectron(and some other problem with finances or something). Carb technology advanced as well and we have very good, though expensive stuff now that needs computers to do all the thinking where us mortal humans did it before. This is progress...I think.
 
I'm on this thread I picked up a few NOS electrons. This will be an interesting ordeal seeing if they can be made to work. Yes a lot of the attraction is the "looks cool" factor. I wanted to get that out there. Don't know about you but at bike shows the crowd looks at carbs, stock = meh, flat side carbs give some wow factor. There I said it! So anyways Lectrons are a deep subject I think. There are several versions over the years and the earlier ones will have issues with use. From some past threads Punks is recommending 34s I am not sure how he sits on the power jet issue. I think the power jet is a must have for two strokes not so sure it's needed on the 4 strokes.
Cornish thanks for posting up that article! that is a help to me. It would be super if someone with experience can enlighten the group on these.
With luck I will get a chance to mess with these this year, don't hold your breath though.
PS I have 32mm carbs. Truth be known I would be happy to get useable carburation at somewhere around stock performance and am not embarrassed to say I would rather have rideable at lower RPM intermediate settings rather than peak horsepower at some high RPM. My thinking is that smaller bore and fairly long intake spigots will aid in that quest. If I am all wet, oh well it's not the first time.
 
Hotdog. I do have a set of VM's on one of my bikes. I also have a set of BS38's on another. My stock stator was less costly then my permanent magnet system and my stock ignition was working fine, but now I have a Pamco. I am happy with both decisions to upgrade with these more modern componets.


jefft
 
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I believe King Kenny, ran Lectrons on his factory XS based Flat Track Bikes. I my self have used them with good result on my Kawasaki H series Dragbikes, Most notably my H1 500, which still holds the national record for top speed in the 1/4 mile @ 134mph. These carbs worked very well on the Dragrace circut as they did not require much adjustment at the various tracks with different alltitudes that i competed at. Plus on a showbike they just look cool. Mitch :thumbsup:
 
So what size Lectron carbs would you run then? I have a 1980 Special 650 fyi and am interested in some electronic carbs.
Also how would you mount them? Do you need special boots?
How bout airboxes?
I've never played with anything other than stock carbs or and air boxes so its an area of ignorance for me.
 
gggGary said:
I'm on this thread I picked up a few NOS electrons. This will be an interesting ordeal seeing if they can be made to work. Yes a lot of the attraction is the "looks cool" factor. I wanted to get that out there. Don't know about you but at bike shows the crowd looks at carbs, stock = meh, flat side carbs give some wow factor. There I said it! So anyways Lectrons are a deep subject I think. There are several versions over the years and the earlier ones will have issues with use. From some past threads Punks is recommending 34s I am not sure how he sits on the power jet issue. I think the power jet is a must have for two strokes not so sure it's needed on the 4 strokes.
Cornish thanks for posting up that article! that is a help to me. It would be super if someone with experience can enlighten the group on these.
With luck I will get a chance to mess with these this year, don't hold your breath though.
PS I have 32mm carbs. Truth be known I would be happy to get useable carburation at somewhere around stock performance and am not embarrassed to say I would rather have rideable at lower RPM intermediate settings rather than peak horsepower at some high RPM. My thinking is that smaller bore and fairly long intake spigots will aid in that quest. If I am all wet, oh well it's not the first time.
Click to expand...

Hey gggGary, are your 32mm carbies from Mikes ? ( I was going to buy those but I got too scared off . Some people on here just don't seem to trust them. ) How do they compare to the 34mmVMs from 650 Central ? Thanks.
 
Lectrons were spec'd for the OU engines built by Axtell's shop for the Yamaha factory dirt track effort in the '70s ... either 36 or 38mm depending upon the track, etc. I have a set of dialed in 36mm Lectrons for my XS650/750 race bike. On the dyno they make about 2 more RWHP than comparably sized VMs, e.g. 72 vs. 70. They aren't legal for AHRMA, so I use VMs instead.
In any engine that is tuned for street use the Mikuni VMs (or flat slides) are a better choice. They'll make essentially the same power, are cheaper and all sorts of jetting info is available for both street and race use.
On the other hand, there is something to be said for cool looking bits on a cool bike.
 

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