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The Lectron Thread
- Thread starter osteoderm
- Start date
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- Tags
- carburetors
osteoderm
out of the box
Well, my Mikunis are sold and gone, so for better or worse I'm sticking with these Lectrons. Overall still excellent, but also still fighting for a low smooth idle.
I ordered firmer slide return springs from Lectron, and that did help with getting a consistent throttle return. Stiffer in the the hand than the light springs I had, but not objectionable. Kevin says that the firmest springs are very firm indeed, and that the medium springs (which I now have) are okay for singles/twins, but probably too stiff for more than two carbs. Interesting things to keep in mind... Given the fairly common refrain about sticky slides at or near idle, I'd suggest that trying medium springs right from the get-go wouldn't be out of the question.
As for that idle... Kevin suggested I try 1/4 richer on the rod to "break up" the lean idle. I tried this for a couple days, and find that my plugs foul after about 20 miles of around-town driving! However, away from idle, everything else had even more pep than usual. I added a 1/4 turn to the powerjets, and the bike was highway champ until I ran out of gas... mileage down almost 20% with all the richening!
I'm tempted now to add idle air bleed screws to fine-tune the idle no matter what the rod setting. I've also gotten some slightly hotter plugs (NKG BPR6EIX) to see if I can control the off-idle fouling that way.
I'm still very optimistic about getting that last 2-3% of tune sorted; it took at least this long to get the Mikunis sorted. I'm building up a Honda XR600R, for which I'm seriously considering a 40mm Lectron... Like any carb, they take time to sort, but so far I'm still stoked on them.
I ordered firmer slide return springs from Lectron, and that did help with getting a consistent throttle return. Stiffer in the the hand than the light springs I had, but not objectionable. Kevin says that the firmest springs are very firm indeed, and that the medium springs (which I now have) are okay for singles/twins, but probably too stiff for more than two carbs. Interesting things to keep in mind... Given the fairly common refrain about sticky slides at or near idle, I'd suggest that trying medium springs right from the get-go wouldn't be out of the question.
As for that idle... Kevin suggested I try 1/4 richer on the rod to "break up" the lean idle. I tried this for a couple days, and find that my plugs foul after about 20 miles of around-town driving! However, away from idle, everything else had even more pep than usual. I added a 1/4 turn to the powerjets, and the bike was highway champ until I ran out of gas... mileage down almost 20% with all the richening!
I'm tempted now to add idle air bleed screws to fine-tune the idle no matter what the rod setting. I've also gotten some slightly hotter plugs (NKG BPR6EIX) to see if I can control the off-idle fouling that way.
I'm still very optimistic about getting that last 2-3% of tune sorted; it took at least this long to get the Mikunis sorted. I'm building up a Honda XR600R, for which I'm seriously considering a 40mm Lectron... Like any carb, they take time to sort, but so far I'm still stoked on them.
FLEA
XS650 Guru
arrived friday,looking forward to fitting next weekend.looks quite impressive
osteoderm
out of the box
Went to hotter plugs, enriched the rods 1/4 turn, and running much better. Fuel mileage down a touch, but overall more fun to ride, so.. I'll take it!
Little trick you could try: Small adjustments to the idle speed ignition timing will require compensary adjustments to the carb's idle stops to maintain idle rpm's, might move you into a better carb idle zone...
osteoderm
out of the box
Went from NKG BPR7EIX Iridium plugs to BPR6EIX.
osteoderm
out of the box
I've been thinking along the same lines... My PAMCO is currently advanced as far as possible just to get acceptable baseline timing; I'm simply out of adjustment there.
I have a Boyer ignition, because it was given to me. Because I ran out of adjustment, I had to rotate the trigger plate on the advance rod just a tad so I could advance my timing. I wouldn't know if the Pamco would be the same, but that was a must for me.
If you retard the idle timing, the carb must be opened slightly, which can do two things. One is allowing more air, giving you more control over mix, second it tends to pull fuel higher in the percolator towers (emulsion tubes), which reduces throttle lag.
What I just wrote doesn't quite make sense, never had to put this kind of thinking down on paper before. Please excuse, hope you get this...
Just to be clear and should have mentioned it, the trigger plate was previously installed a little off thus the reason for me moving it. I too, had run out of adjustment as a result of improper installation
osteoderm
out of the box
Similar situation here... the pickup component on my PAMCO board is a little askew, so I need to have the whole unit cranked a little further clockwise than ideal in order to make timing. Annoying, but so far not enough of a bother to be worth replacing.
osteoderm
out of the box
Hotter plugs and 1/4 richer on the rods, and running pretty well. However, I'm getting a weird muck in the carb intakes, upstream of the slide:
Downstream, the bore of the carb is clean. The muck wipes off easily. I'm not discounting that this might be an indicator of some other non-carb-related issue (at least not directly), but can anyone say what this might be a symptom of? Some sort of intake reversion?
I'm also increasingly convinced that these are standard/low-velocity Lectrons. With the large XS intake ports, high-velocity Lectrons are preferred; maybe this is part of the puzzle?
Downstream, the bore of the carb is clean. The muck wipes off easily. I'm not discounting that this might be an indicator of some other non-carb-related issue (at least not directly), but can anyone say what this might be a symptom of? Some sort of intake reversion?
I'm also increasingly convinced that these are standard/low-velocity Lectrons. With the large XS intake ports, high-velocity Lectrons are preferred; maybe this is part of the puzzle?
Oboy, a mystery!
+1 on the reversion.
2 thoughts on the goo.
Could be some sort of seal/o-ring melting, possible fuel incompatibility.
Could be some sort of oil/fuel/carbon/sludge spewing back from inside the cylinder, driven by reversion, but the fuel delivered past the slide washes off the evidence on the downstream side...
+1 on the reversion.
2 thoughts on the goo.
Could be some sort of seal/o-ring melting, possible fuel incompatibility.
Could be some sort of oil/fuel/carbon/sludge spewing back from inside the cylinder, driven by reversion, but the fuel delivered past the slide washes off the evidence on the downstream side...
osteoderm
out of the box
+2 on reversion: removed the carbs and intakes, and had a good poke around the inlet tracts... obvious heavy carbon deposits, while the cylinders/piston tops themselves are fairly clean. I cleaned the valves/inlets as best I good, blasted with carb cleaner and air, then re-assembled. Tore around the 'hood a few times for heat, and misted a bunch of clean water into the intake bells at fast idle to steam the valves.
Things look a little better, but the fast/stumbling off-idle condition remains. Bah. It's late in the season, and I'm balls-deep into another bike project, so I'm feeling less motivated to dig into this much further.
Things look a little better, but the fast/stumbling off-idle condition remains. Bah. It's late in the season, and I'm balls-deep into another bike project, so I'm feeling less motivated to dig into this much further.
Then..... a suspicous eyeball on the intake guide/seal...
osteoderm
out of the box
This crossed my mind as well. On the other hand, I have zero oil consumption, no smoking, and the cylinders are clean/dry/grey. This only started up after I enriched the carbs 1/4 turn and switched to hotter plugs. Also, this was never an issue with the Mikuni's... There's something about this intake/carb/exhaust combo that just isn't playing well together.
Well, that or something has gone very wrong in my valvetrain
. Still, besides the idle/off-idle issues, the bike runs like a boss.
Some sort of momentary fuel wash? Enuff to wash the valve, but not enuff to show up further downstream?
I know nothing of the Lectron emulsification system. If these were Mikuni's, I'd be looking at the bleed air system...
osteoderm
out of the box
I see where you're going. I still feel like the reversion is a symptom, not the actual problem. I have clear plugged lines on my manifold barbs (for vacuum gauge connections) in which I can watch fuel moisture pulsing; I'm definitely getting a much broader manifold pressure pulse than I'd otherwise expect.
The worse it gets, the fouler the valves, the worse it gets... Fouling keeping the intake valves from sealing? Time to double-check the intake valve clearances, yup.
The Lectrons have no bleed system, and no pilot jet. Metering rod height sets the baseline idle fuel delivery, and the only other factors that might dump additional fuel are a failed float or a failed choke/enricher/starter valve. The float bowls are clear with molded-in reference lines, so it's easy to observe float level/activity (and it looks good). Choke valve passes a leakdown test.
It could all be some weird resonance issue with the exhaust and intake runner lengths; the Mikuni's as installed on the bike put the needle jet 1/4" farther away from the intake valve, and the downstream side of the roundslide 3/8" or so closer to the intake valve (compared to the Lectrons). I would like to try adding length to the intake runners, but I didn't have any additional hose handy... and still a few other things I'd like to spend time on this long weekend!
Oh, yeah, me too, just can't seem to get up...
If you've got no emulsification system, I'd suspect raw fuel. Ever seen the mixing flutterbye/butterfly device used on propane conversions?
Under the right conditions, I've seen reversion on this kind of bike that was bad enuff to create a hovering 'fog' in the carb inlet, nothing going in, nothing coming out, no power. But, like you said, that's not the 'cause' here.
If you've got no emulsification system, I'd suspect raw fuel. Ever seen the mixing flutterbye/butterfly device used on propane conversions?
Under the right conditions, I've seen reversion on this kind of bike that was bad enuff to create a hovering 'fog' in the carb inlet, nothing going in, nothing coming out, no power. But, like you said, that's not the 'cause' here.
