Dead Motoplat - '74 125 Six Day

[Motobros-Dave]

Hi all . . . . we've just discovered the original Motoplat CDI ignition is probably toast.  From what "tests" I've found online I think the ignition coil might be ok which leads me to believe the stator is faulty.

The stator looks a little rough and when we first took the magneto cover off the engine we found an incredible amount of corrosion on the rotor magnet and throughout the compartment, so it's not too surprising if poor maintenance has lead to stator failure.

My question now is:  is there a modern alternative that we can order to replace the Motoplat system ??

Thanks in advance,

- Dave

[Larry Perkins]

MZB makes an ignition if you want to run lights and PVL and HPI make ones that are less dollars but won't do the lights.  Al Buehner has the PVL and MZB and Gary Ellis has the HPI which is the least expensive.  You can also send the old Motoplat to Vance Smith and he can probably rewind it.

Larry P

[Daniel P. McEntee]

Given your description of what the ignition side looked like, I would thoroughly clean EVERYTHING from the stator up to the coil including the plug connections and retest everything. I have seen some "fixed" this way. Any ignition system won't tolerate the high resistance from corroded connections and Motoplats really need a good ground from a nice, clean seating of the stator plate. If it still won't fire, contact Vance Smith with your particulars. Vance has the repair down to a science and can tell you what 'plat paerts will work with each other also. After you make your decision on the ignition, you need to really clean the whole case area and seal it with something like paint oe at least a primer, and then re-clean where the stator sits. Then, add a vent to the top of your case, so that doesn't happen again. When the engine heats up and cools down, especially after going through water, it can draw moisture and trap it with no way for it to dry out. You can't stop or seal out condensation. Even with a vent, it's a good idea to pull the case every now and then to let it air out  and dry, and give things a good look see while it's off. Good luck with it and have fun!
  Type at you later,
  Dan McEntee

[G Ellis]

I sell HPI ignition $270.00.

[Motobros-Dave]

Hi, thanks for the info. I have an update . . . . though I had previously cleaned all ignition mounting surfaces, today I made double-sure and cleaned them all again including both sides of the stator core plates, then put all the components together. Before mounting the flywheel magnet I placed a piece of sheet steel across the back of the magnet and found virtually no strength, the piece of steel lifted off easily with barely detectable resistance.  Touching a screwdriver to the inside of each magnet does show there is some magnetism still present though it seems weak.

After mounting the flywheel and securing the nut, I directly grounded the coil to the engine (engine is on the bench with head removed) and then used an electric drill to spin the engine forward looking for spark on the grounded plug.

Much to my surprise, after I got the rpm's up a bit, I did see spark at the plug but it looks rather weak and dubious whether it would spark under compression.

So, in your opinions, is it safe to assume that the stator is probably ok and useable and that the fault lies with a weak magnet flywheel.  My next question is can a replacement flywheel be purchased separately?   Thanks - Dave