Calling all Lectron experts! I have been tinkering on my '77 Penton 400 MC-5 that has what I think is the original style Lectron that I assume came on it stock. The bike idles a little high, even with the speed adjuster screwed out to where the slide seats at the bottom. I am completely new with Lectrons but have the instructions that were in the Penton manual, and began to look for any kind of air leak that might be obvious. In trying the old aerosol spray method of looking for an air leak, the engine RPM dropped when I sprayed directly on the speed or idle adjustment screw. The screw does appear to have some worn threads and I have been tinkering with it trying various methods of sealing the threads until I can order some parts from Al B for it on Monday. The slide has some wear or what I call a "witness" mark on the engine side. Could this also be a source of air leaking in at idle? I am looking at turning the metering rod in a bit to see if that helps the situation, and it already is just about full in. I'm going to take what I can get with it, and order up the next size, but there is no markings of any kind that I can see on the rod. The manual has a drawing that shows the various metering rod profiles. Is that the only way of identifying the rods, by the profile of the taper? Mine appears to be straight and flat, and I take that as meaning it's the the leanest or #5 rod? Next is the 51, 52 and 53. If I'm already turning in that far, should I make the jump to the 52? Just want to make sure I spend smart money on the rods. All the other parts are pretty reasonable, and like most people would like to make the first choice the correct choice. Otherwise, the engine seems to run just fine, but haven't had the opportunity to really run it to make a plug check worth while. Ignition side crank seal also comes to mind, but spraying around the speed adjuster has such a quick and positive response that I don't think it would do that if it were a crank seal. Also, if I just out a slight pressure on the choke lever,the RPM drops, and the engine will quit if I leave my finger on it for too long, and I take that as a sign that the engine vacuum is quite good. Barn yard shade tree mechanics at it's best! Thanks in advance for any and all help.
Type at you later,
Dan McEntee
PS: Forgot to ask about the O-ring at the top of the clamp of the adjuster. How critical is that O-Ring. Mine looks OK but will replace if necessary. I have been unable to remove what is there, and I'm wondering how does one remove that assembly to replace the O-ring?
Helmet "Speedy" Clausen is the Lectron specialist/retailer, usually frequenting the Vinduro site more so than the POG, but chimes in from time to time. The 175 Pentons used Lectrons, but not any other size unless possibly some 125 KTM's originally to my knowledge. Your 77 400 MC5 would have come stock with a 38mm Bing carb. Mike
Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S
1975 Can Am 175 TNT & 77 250 Black Widow
1979 Husqvarna OR390
1976-78 RM & 77-79 PE Suzuki's
1974 CR250M 07 CR125R 79 CR250R
Dan give me a call I can help.
I bought a 38mm Lectron originally for another bike, and Speedy said a 6-1 is recommended but sent me a 6-2 also just in case I needed to go richer for very cold weather. This carb had a power jet so I would guess a non power jet carb would need a richer metering rod.
Brian
Thanks for the feed back. This is the first Lectron I have ever had my hands on, and with it being an older one, I just want to be sure of what I'm looking at and needing. If it was a Bing or Mikuni, I would have been been more familiar with what to look for and do. After I made my post, I put some silicone on the adjusting screw to seal it and let it cure, along with some on the rubber choke cap to help on that end if there were any leaks. The result was that it idled much better, but the rod is all the way in, and the adjuster is not touching the slide. I'm sure I have enough slack in the throttle cable for the slide to bottom out. The slide has some considerable wear on the engine side, and I suspect that it may still be passing some air at that point. I checked the Lectron web site, and the info I found there says that they rods on the early carbs were not marked, and I can't find anything on it with a magnifying glass. The Penton manual I got with the bike has a section on the Lectron carb and their examples in that section are for the #5 series of rods. In consulting around I get the feeling that is what was probably in the carb from the factory. I have a feeling that the original owner made the adjustment to the max rich side to address the issue as the rest of the parts in the carb wore over time. I keep reminding myself that this is all the original stuff! The bike is an MC-5 but it had a light kit on it, and several Missouri State inspection stickers on the forks, and was obviously not abused and was in pretty good original condition. I think it was used as a farm bike, like people use quads for now. Bet it got him to the North Forty in pretty quick fashion! I was just concerned that I wasn't able to adjust the idle down any, and if all were normal, I should have enough control and an adjustment range to set the idle from too rich to idle to lean enough for the RPM to be up a bit. The rest of the throttle response is real nice, and no indication of being lean. I haven't been able to do any real "Rudder Runs" to read the plug, but in just running it up and down the street, it sounds and feels real nice, so I think I'm on the right track. I'm getting an email off to Al B tonight and we'll see what he has for parts in stock.
Thanks again,
Dan McEntee
VMX magazine just featured a Lectron session this month
Hi Kip;
Which issue number has the Lectron article? Is it current issue #56? Trying to locate it on line but haven't seen any description of the article. I got new parts from Al B and they made all the difference in the world, but would like to have this article anyway.
Thanks a lot,
Dan McEntee
Dan - it's the current issue - don't have mine handy to check the issue number but it has the Ossa on the cover.
Clark
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"We the willing, led by the unknowing, are doing the impossible, for the ungrateful. We have done so much, for so long, with so little, that we are now qualified to do almost anything, with nothing."
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