Topic: Cycle Exchange Dragbike project

[dragracer]

Looks like Kenny is back on the dragbike project again.  2025 could be its debut if he keeps making progress.

[dusterdude]

Cool

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[seanbarney41]

oh lord

[Don R]

 Do those Lectrons have a power jet? Ours was on the other side of the carb.

[Tracksnblades1]

Do those Lectrons have a power jet? Ours was on the other side of the carb.

Is that in addition to a main jet…?
Or is it similar to a mikuni and Keihin main jet and needle arrangement..?

[dragracer]

Do those Lectrons have a power jet? Ours was on the other side of the carb.

Yes, those are power jet Lectrons. It has no real function for low to mid range but works primarily on top end.

There's no main jet on a Lectron.  They are venturi affect carbs. These bad boys only do 2 functions, idle and full throttle. You basic adjust your best lean idle condition by lengthening or shortening the metering rod. You can change metering rods that have different tapers for more or less fuel overall. They're great carbs but will seasonally need to be adjusted due to oxygen levels from warm to hot temps. Elevation also has an impact. If you're serious about going fast in drag racing  or even land speed using carburetion, this is the only way to go. Otherwise,  fuel injection is your best bet.

[Tracksnblades1]

Do those Lectrons have a power jet? Ours was on the other side of the carb.

Yes, those are power jet Lectrons. It has no real function for low to mid range but works primarily on top end.

There's no main jet on a Lectron.  They are venturi affect carbs. These bad boys only do 2 functions, idle and full throttle. You basic adjust your best lean idle condition by lengthening or shortening the metering rod. You can change metering rods that have different tapers for more or less fuel overall. They're great carbs but will seasonally need to be adjusted due to oxygen levels from warm to hot temps. Elevation also has an impact. If you're serious about going fast in drag racing  or even land speed using carburetion, this is the only way to go. Otherwise,  fuel injection is your best bet.

👍 good to know…

Sounds a lot like an old Enderle barrel valve injection set up.. on or off no in between….

[Don R]

  I think the grandfather of the Lectron was the Lake injector.

[seanbarney41]

I think Lectrons get a bad rap.  Last bike I rode with a Lectron carb was a 2020 (or so, they have remained unchanged for at least 20 years) Yamaha YZ250X, so 2 stroke engine tuned and geared for enduro/woods racing, NOT motocross.  I am guessing numbers around 40-50 hp and bike around 220 lbs.  It performed like a slightly crisper stocker...operated fine at all rpms and throttle positions.  You could putt putt around slow or rip it through the gears in the powerband.  It was easy to ride in a tight single track...just DON"T whiskey throttle cuz it's gonna GO!

[dragracer]

Lectron does design carbs that are capable of some part throttle usage in some applications. The drag only carbs only do 2 things for the most part. You won't see anyone riding around on the street with them.

[simon#42]

no idle on a lectron , at least not the early ones i have . they were the carb to have on tz yamahas after kenny roberts used them on his tz750 . there are much better carbs available these days but for drag racing the carbs dont need to be very complicated .

[Don R]

 Our Lectron had a needle with a tapered flat side, the transition from idle to wide open depended on the rate of taper and how far you turned the needle in or out. I tuned it with an EGT gauge and recorder. I did a little WOT tuning with the power jet.

 My Drag racing mentor had an Enderle stack injection on a super comp 8.90 car. He had the barrel valve spool modified with a tear shaped slot rather than a big fuel hole, that helped with coming on and off the throttle stop.

[dragracer]

We tune our bikes at idle to get best plug color and throttle response. Of course we also check the plug after a big end pass to tweak it more. I've got Lectrons one 5 of them and bought my first new set in 1996. Best money i ever spent. They're sometimes finicky on a no bar bike when you're not  launching full throttle but you eventually find the sweet spot.

[simon#42]

I feel old now , I bought my first set in 1978 . I still have a few sets and a box of needles . They worked great on a tz or rotax neither of which would tick over at all on any type of carb . They all got put away when dellorto brought a smooth bore carb out . Used them for a couple of years until the first proper flat sides arrived .

[Tracksnblades1]

Our Lectron had a needle with a tapered flat side, the transition from idle to wide open depended on the rate of taper and how far you turned the needle in or out. I tuned it with an EGT gauge and recorder. I did a little WOT tuning with the power jet.

 My Drag racing mentor had an Enderle stack injection on a super comp 8.90 car. He had the barrel valve spool modified with a tear shaped slot rather than a big fuel hole, that helped with coming on and off the throttle stop.

That’s interesting. The barrel spools I’ve been around had a v notch or just a rectangle slot..
The barrel either had the middle of the side removed with radius corners or square corners…
Set the butterfly’s with a feeler gauge first, flow it, and get it to idle with the barrel valve to the greater degree..
What fuel was your mentor running..?

[Don R]

 He was on methanol, they ran the midwest injected funnycar circuit. They were among the early drag racers to run nitrous on alcohol.
  The modified spool was on a super comp car. He actually did things the hard way just to make it sporting. His last car was an early pro stock camaro, he tuned it to run 8.90 with timing retards and rev limiters, a throttle stop was too easy.   
 I never saw the barrel valve but remembered him telling me about it when we were running the Lectron.