Talk:Guide to Motobecane spark and timing

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I need some help on step 4 which reads:

Remove spark plug cap from external coil and examine plug wire where it makes an electrical contact inside the coil, this connection is often bad. Is the wire corroded? Does there look like a chance the connection was not tight? Strip a half inch of the insulator off the spark plug wire, then cut the copper off so it extends ¼”, push the copper out to the sides, and push a small screw driver into the opening to create a small opening (PIC 6). Now carefully attach the spark plug wire to the coil, make sure the connection you just cleaned up fits snugly on the coils.

Basically, this paragraph offers few clues as to what to actually do, and Pic 6 is blurry, small and doesn't help at all.

First, on the "Strip a half inch of the insulator off the spark plug wire" part, which end of the wire are we even talking about?

Which end do I strip the insulation off? The part that is in the Coil or do I extract the wire from the Spark Plug Cap?

On the coil side, I am not sure what to do, no wire is even exposed. There is no wire visible on the coil side (it is a Motobecane 50), just a plastic cover with a pin hole in the middle. I assume induction pushes the spark through the plastic/rubber so I doubt I want to be cutting this wire open, or do I?

Can somebody please explain this paragraph more clearly, and hopefully offer a few pics on what is happening here?

Much obliged, Bill

Next Timing Clarification

I am on to trying to check the timing, and using both the Motobecane Technical Manual and this Guide. Neither is written well or clearly. I am a Diesel Mechanic and have read many technical guides and repair manuals, wow are these both un-clear and non-specific confusingly poor gramar. I am repairing a Motobecane 50, I can't find a plate with the info on it, so I am assuming the previous owner is correct.

First Guide issue: Pull the black, and brown wires off the stator plate, disconnect the grey wire that is connecting the stator plate with the spark plug, and the kill switch, connect a multimeter to the grey wire you just disconnected, and the other end to the engine ground. Set the multimeter to continuity, and then turn the engine over by hand. With every rotation the multimeter should change from open to closed circuit, you should see the points opening and closing as well. (PIC 8).

Besides Pic 8 being only sightly entertaining, I finally figured out the grey wire and got that one, and there are no black wires near the Stator Plate, just a white and a brown one. Can I assume this is what you call the black and brown wires? I will assume so.

Second Problem: I am on a 12 Volt System, I assume, because I have three copper coils in the magneto (one blue, brown, white). so on the Note: on 12v systems (3 coil) the flywheel must be removed, the three wires attached to the points must be removed and kept from grounding (unscrew and place a piece of paper between them and the points) place a lead one eash (sp) side of the points and test to see if the meter registers open and close before trying to set timing, the systems are wired differently but the other steps of the procedure are the same. 12v systems are on 78 and later models. (although the ignition is still 6v for both systems, the lighting is split with 12v going to the head and tail lights, and another 6v circuit for the brake light and horn) The Three Wires must be removed. The only wires in there are thin copper wires solder in and becoming the coil. The grey wire is detached at the ignition coil and goes to the point (in the back of the point). What three wires must be removed? There are several bolts (hex heads) and one screw in the stator plate area, but none with a wire.

Can somebody who has done this procedure on a Motobecane 50 with a 12 V system advise me on the proper timing technique.

Additionally, the repair manual states that a Ohm Meter is insufficient, and a timing light must be used. Can somebody explain this to me or can I still use the 2mm BTDC by using the measuring tool created by another person on this forumn.

Thanks, Bill

Forums would be more helpful, methinks

I've never done a formal survey on how often people check talk pages or the recent changes, but I'm pretty sure that I am one of about three people who will read this page sometime in the next year. I don't know squat about Motobecanes, so I can't offer too much assistance. Given that, your best bet is probably to repeat all of this on the Repair forum. If someone explains it better there, I can work on cleaning this article up a little and making it easier to understand for other people. Actually, I could probably go clean up sentence structure and spelling stuff now, although I don't think that's going to help you very much.

In general though, if step 4 is explaining what I think it's explaining, I have never heard of anyone stripping the spark plug wire like that. On Puchs, I will definitely cut 1/2 of an inch of the old ends to make sure I get a good connection when I reattach the wire to the spark plug boot or to the ignition coil, but I have never stripped the wire to expose the inner copper core like it sounds like they're describing here. Of course, it's also possible that this is a special Motobecane thing that I wouldn't understand.

On the wiring, your best bet is probably to find a wiring diagram that matches what you have and then try to work back from there. If there's a wire that goes from magneto area to an external coil, that's probably the one you're looking for. If you have an internal ignition coil, though, I'm not sure what to tell you. I bookmarked this a while back. Maybe it'll help? Looks like a Motobecane in the pics, anyway.

Often, the way the manual recommends that we do something is not the way that we do it. Sometimes this is because we're too cheap to buy the correct tool, and sometimes it's because the correct tool was a dealers-only thing from back in the 70's, and NOBODY has them. In situations like these, we invent our own methods. If someone posts a method on the forums, their method will have worked well enough at least for them. A lot of homebrew methods are pretty good too -- maybe if we had crazy high performance racing engines we'd want more precision, but it's a moped. More accuracy is great, but less accuracy often works pretty darn well too. So yeah, if you can figure out the "correct" way to do it per the manual, go for it. Otherwise, you might as well try the other method and see if it works for you.

Good luck!

--Mycider 14:20, 6 December 2009 (EST)

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